Appellate Review of Daubert Rulings
By Steve Klepper
The Supreme Court of Maryland adopted the federal Daubert standard for admission of expert testimony in 2020.[1] Given that Daubert rulings are discretionary, the abuse-of-discretion standard governs appellate review of expert testimony.[2] During the summer of 2023, the Supreme Court of Maryland issued three opinions holding that trial judges abused their discretion—at least in part—when they admitted or excluded expert testimony.[3] In the last of the three cases, Justice Brynja Booth authored a concurring opinion noting how the Court was applying lessdeference than in other discretionary contexts, and she urged her colleagues to clarify the nature of review.[4]
This article posits that Daubert errors fall into two main categories: procedural and substantive. Procedural errors occur when a trial court misunderstands an aspect of the Daubert framework.[5] In effect, the trial judge has misread Maryland Rule 5-702, which governs expert testimony.[6] A misreading of an evidentiary rule is legal error that is reviewed de novo, meaning without deference.[7] Substantive error occurs when a trial judge follows the Daubert framework but reaches a result to which an appellate courts cannot defer because either the trial judge has abused their[8] discretion in the traditional sense or the Supreme Court of Maryland has decided to draw a boundary circumscribing all trial judges’ discretion.[9] Such vocabulary not only accurately describes the nature of judicial review but also reduces friction between trial judges and appellate courts.
I. Maryland’s Adoption of Daubert
A. The Pre-2020 Frye-Reed Regime
From 1978 to 2020, Maryland courts applied the Frye-Reed standard for the admission of expert testimony.[10] Its name derived from the 1923 D.C. Circuit decision in Frye v. United States,[11] and the 1978 Supreme Court of Maryland decision in Reed v. State.[12] The standard required that “the basis of [an expert’s] opinion must be shown to be generally accepted as reliable within the . . . relevant scientific community.”[13]
Maryland’s Frye-Reed standard was the subject of “jurisprudential drift”[14] after the 1993 Supreme Court of the United States decision in Daubert v. Merrell Dow Pharmaceuticals, Inc.[15]The Daubert Court held that “the Frye test was superseded by the adoption of the Federal Rules of Evidence” in 1975.[16] Rule 702 of the Federal Rules of Evidence, as originally adopted, provided: “If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.”[17] The Daubert Court held that the “austere [general acceptance] standard, absent from, and incompatible with, the Federal Rules of Evidence, should not be applied in federal trials.”[18]
In place of Frye’s standard, the Daubert decision “provided a list of flexible factors to help courts determine the reliability of expert testimony.”[19] While “[a] supermajority of states followed the Supreme Court’s lead and replaced their respective Frye standards with the Daubert standard[,]”Maryland did not.[20]
Although Maryland did not adopt the Daubert standard, the “Frye-Reed standard announced in 1978 slowly morphed into a ‘Frye-Reed Plus’ standard, implicitly and explicitly relying on and adopting several Daubert principles.”[21] In 1994, one year after the Daubert decision, the Supreme Court of Maryland adopted Maryland Rule 5-702, which provided:
Expert testimony may be admitted, in the form of an opinion or otherwise, if the court determines that the testimony will assist the trier of fact to understand the evidence or to determine a fact in issue. In making that determination, the court shall determine (1) whether the witness is qualified as an expert by knowledge, skill, experience, training, or education, (2) the appropriateness of the expert testimony on the particular subject, and (3) whether a sufficient factual basis exists to support the expert testimony.[22]
When adopting Rule 5-702, the Court “blessed a Committee Note that stated that Rule 5-702 was not intended to overrule Reed or other cases adopting the Frye standard, and that the ‘required scientific foundation for the admission of novel scientific techniques or principles is left to development through case law.’”[23]
Nevertheless, Maryland incorporated several key Daubert principles through case law.[24] For example, the 2009 decision in Blackwell v. Wyeth affirmed the exclusion of expert testimony about the supposed “relationship between thimerosal and autism[,]”[25] holding that a “court may conclude that there is simply too great an analytical gap between the data and the opinion proffered.”[26] To avoid “an analytical gap[,]” the Blackwell decision required both a generally accepted methodology and analysis.[27]
The Blackwell decision applied three appellate-review standards to the trial judge’s evidentiary rulings. First, the clear error review to the trial judge’s factual findings on the factual predicates for the expert’s testimony.[28] Second, the Court applied de novo review to the Frye-Reed determination “that neither the genetic susceptibility theory nor the tests used to determine if [plaintiffs’ son’s] autism was due to genetic susceptibility were generally accepted in the relevant scientific field.”[29] Finally, the Court applied the abuse-of-discretion review to the Rule 5-702, finding that the experts’ “fields of expertise were not relevant to the specific bodies of science that purport to maintain generally acceptable scientific methods and analyses related to autism and its causes.”[30]
In an influential 2017 concurrence in Savage v. State, Judge Sally Adkins urged the outright adoption of the Daubert standard in place of Frye-Reed.[31] She observed that under Blackwell’s “analytical gap” holding, “a trial court may have to analyze the reliability of an expert’s methodology twice—once under Frye-Reed and again under Maryland Rule 5-702(3).”[32] Instead, “adopting the Daubert approach and confining our evaluation of scientific expert testimony to the requirements of Rule 5-702 would eliminate this repetition.”[33]
B. The Rochkind Decision’s Embrace of Daubert
In 2020, after Judge Adkins retired, the Court accepted her invitation to adopt the Daubert standard.[34] The appeal in Rochkind v. Stevenson addressed a judgment against a landlord for a child’s alleged injuries from exposure to lead paint.[35] After the Appellate Court rejected the landlord’s challenges to the plaintiff’s expert’s testimony on causation, the Supreme Court of Maryland granted the landlord’s petition for a writ of certiorari to consider whether to adopt the Daubert standard.[36] Crediting Judge Adkins for “blaz[ing] the trail,” Judge Joseph Getty’s opinion for the Court “implement[ed] a single standard by which courts evaluate all expert testimony: Daubert.”[37] In doing so, the Rochkind decision aligned Maryland with “the supermajority of sister states and the federal courts[.]”[38]
Quoting at length a federal decision by Judge Paul Grimm of the U.S. District Court of Maryland, Rochkind held that under “the parties and the trial court are forced to reckon with the factors that really do determine whether the evidence is reliable, relevant and ‘fits’ the case at issue.”[39] Frye-Reed’s primary “shortcoming” was “that it excused the court from even having to try to understand the evidence at issue.”[40] Under Frye-Reed, a “court ‘only had to assure itself that among the people involved in the field, the technique was acceptable as reliable.’”[41]
The Court gave a non-exhaustive list of ten factors—five from the original Daubert opinion and five from later authority—for interpreting and applying Rule 5-702:
(1) whether a theory or technique can be (and has been) tested;
(2) whether a theory or technique has been subjected to peer review and publication;
(3) whether a particular scientific technique has a known or potential rate of error;
(4) the existence and maintenance of standards and controls; . . .
(5) whether a theory or technique is generally accepted[;] . . .
(6) whether experts are proposing to testify about matters growing naturally and directly out of research they have conducted independent of the litigation, or whether they have developed their opinions expressly for purposes of testifying;
(7) whether the expert has unjustifiably extrapolated from an accepted premise to an unfounded conclusion;
(8) whether the expert has adequately accounted for obvious alternative explanations;
(9) whether the expert is being as careful as [they] would be in [their] regular professional work outside [their] paid litigation consulting; and
(10) whether the field of expertise claimed by the expert is known to reach reliable results for the type of opinion the expert would give.[42]
Turning to the standard of appellate review, Rochkind held that the shift to Daubert would confine all appellate review of the exclusion and admission of expert testimony to an abuse of discretion standard, leaving behind the “separate, and potentially outcome determinative, standards of review—de novofor Frye–Reed and abuse of discretion for Rule 5-702[.]”[43]
The majority in Rochkind was slim, with a notable split between judges who had served as trial judges under the Frye-Reed regime and judges who had not.[44] The four-member majority was appointed to the court directly from private practice or government service, without serving as trial judges.[45] All three dissenters were former trial judges in Maryland.[46]
C. The First Post-Rochkind Decisions
Remanding for the trial court to apply the Daubert standard to the causation expert’s testimony, the Rochkind Court held that its decision also applied to “any other cases that are pending on direct appeal when this opinion is filed, where the relevant question has been preserved for appellate review.”[47]
The first post-Rochkind case involving an expert ruling, Frankel v. Deane, only tangentially addressed the Daubert standard.[48] Four months before Rochkind, the trial court held a Frye-Reed hearing in a medical malpractice case.[49] There, the court excluded the plaintiff’s expert, resulting in the entry of summary judgment, because the opinion was “based primarily on his examination of Plaintiff almost two years after the fact, and on the Plaintiff’s shaky, uncertain self-reporting to him . . . without him having reviewed the professionally detailed notes and records” of the treating physicians.[50] Justice Steven Gould’s opinion for the Court held that the trial court exceeded its Rule 5-702 role because the treating physicians’ notes “were disputed in multiple material respects by their patient,” and the “conflicting evidence on these issues teed up a classic credibility contest for the jury—not the court—to resolve.”[51] Remanding for a Daubert hearing, the Court further held that in “light of the nature and extent of the factual and credibility findings made by the trial judge that granted summary judgment and to avoid any appearance of partiality going forward, this case should be assigned to a different judge for all further proceedings.”[52] Justice Shirley Watts, who authored the Rochkind dissent, dissented in part in Frankel.[53] She agreed that the trial court erred but believed that a Daubert hearing was unnecessary because the Court’s decision resolved all challenges the defendants had preserved for review.[54]
The appeal in State v. Matthews was “the first opportunity for [the Court] to address, post-Rochkind, whether a trial court erred in deciding the admissibility of expert testimony.”[55] In a murder trial, the circuit court admitted testimony from a Federal Bureau of Investigation (“FBI”) scientist who was part of a team that used reverse projection photogrammetry to estimate a suspected shooter’s probable height, “plus or minus two-thirds of an inch,” from a home surveillance video.[56] The FBI’s report identified several variables that could cause “the degree of uncertainty in this measurement [to] be significantly greater.”[57] At the pretrial Daubert hearing, the FBI scientist noted that those variables included “the subject to camera distance, the resolution of the imagery, the unevenness of the landscape, and the body position of the subject.”[58] The FBI scientist testified: “I don’t have a scientific way of quantifying how those dimensions had an effect on my measurement and consequently I wanted in an abundance of caution to mention them.”[59] The Appellate Court of Maryland held that the trial court abused its discretion in admitting the testimony because the FBI failed to analyze the effect of the immeasurable variables, yielding an unreliable, deficient height calculation.[60]
Holding that the trial court acted within its broad discretion in admitting the testimony, the Supreme Court of Maryland began its analysis by reciting the general test for abuse of discretion.[61] Reversal requires that “the trial court’s decision must be well removed from any center mark imagined by the reviewing court and beyond the fringe of what that court deems minimally acceptable.”[62] There was “no dispute that [the] methodology was reliable[,]” and there was no “analytical gap in her proffered testimony.”[63] Thus, “[t]he unknown degree of uncertainty concerning the accuracy of [the] height estimate went to the weight the jury should give to the expert testimony, not to its admissibility.”[64]
The Court stressed that “it is the rare case in which a Maryland trial court’s exercise of discretion to admit or deny expert testimony will be overturned[,]” and that Matthews was “not one of those cases.”[65] Again dissenting, Justice Watts would have reversed the admission of the FBI scientist’s expert testimony.[66] As to the “rare case” language in the majority’s opinion, Justice Watts noted that whether “this prediction will prove to be accurate remains to be seen.”[67]
II. Three “Rare Cases” of Abuses of Discretion in One Term
In the fourteen months after Matthews, the Supreme Court of Maryland decided three important Daubert appeals.[68] Straining the “rare case” prediction, the Court held in all three cases that the trial court abused its discretion at least in part.[69]
A. The Abruquah Decision (Firearm Identification)
In Abruquah v. State, the Supreme Court of Maryland held that the trial court abused its discretion by allowing a ballistics expert to offer an unqualified opinion tracing bullets to a specific firearm.[70] The Court explained that “[f]irearms identification, a subset of toolmark identification, is ‘the practice of investigating whether a bullet, cartridge case or other ammunition component or fragment can be traced to a particular suspect weapon.”[71] In Abruquah,the police recovered two guns, including a Taurus .38 Special, from a murder suspect’s home.[72] Over objection, the trial court allowed a county police firearms examiner, Scott McVeigh, to testify that the Taurus revolver had fired the “four bullets and one bullet fragment recovered from the crime scene . . . .”[73] The trial in Abruquah took place before Rochkind but was remanded for reconsideration under the Daubert standard.[74] Ultimately, the trial court held an evidentiary hearing and again found the testimony admissible under Rochkind’s ten factors.[75]
The Court granted review, before the Appellate Court of Maryland heard the appeal, “to address whether the firearms identification methodology . . . is sufficiently reliable to allow a firearms examiner, without any qualification, to identify a specific firearm as the source of a questioned bullet or cartridge case found at a crime scene.”[76] By a four-to-three majority, the Court, in an opinion by Chief Justice Matthew Fader, reversed the trial court’s Daubert ruling.[77] The Association of Firearm and Tool Mark Examiners’ Theory of Identification (“AFTE Theory”) was long “accepted by law enforcement organizations and courts without significant challenge,” but “the advent of Daubert, work exposing the unreliability of other previously accepted forensic techniques, and recent reports questioning the foundations underlying firearms identification have led to greater skepticism.”[78] In a 2009 report, the National Research Council of the National Academies of Science “criticized the AFTE Theory,” based on “lacking specificity in its protocols; producing results that are not shown to be accurate, repeatable, and reproducible; lacking databases and imaging that could improve the method; having deficiencies in proficiency training; and requiring examiners to offer opinions based on their own experiences without articulated standards.”[79] Similarly, a 2016 report by the President’s Council of Advisors on Science and Technology “described the AFTE Theory as a ‘circular’ method that lacks ‘foundational validity’ because appropriate studies had not confirmed its accuracy, repeatability, and reproducibility.”[80] Following these reports, courts, including Maryland federal courts, began restricting AFTE Theory testimony.[81]
The Court’s opinion noted that Judge Grimm, from whom the court had quoted extensively in Rochkind,[82] made a 2018 oral ruling involving the same ballistics expert, Scott McVeigh.[83] Judge Grimm, surveying the known flaws in firearms identification, permitted Mr. McVeigh to testify “only ‘that the marks that were produced by the . . . cartridges are consistent with the marks that were found on the’ recovered firearm” but “precluded him from offering any opinion that the cartridges ‘were fired by the same gun’ or expressing ‘any confidence level’ in his opinion.”[84] Other courts have further limited the scope of firearm identification testimony due to the uncertainty.[85]
Consistent with these persuasive authorities, the Abruquah Court held that “the methodology of firearms identification presented to the circuit court did not provide a reliable basis for Mr. McVeigh’s unqualified opinion that four bullets and one bullet fragment found at the crime scene in this case were fired from [the] Taurus revolver.”[86] The Court identified “an analytical gap between the type of opinion firearms identification can reliably support and the opinion Mr. McVeigh offered.”[87]
Justice Michele Hotten penned one of two dissenting opinions in Abruquah.[88] She noted that the trial court’s decision to allow Mr. McVeigh’s testimony aligned with Rochkind’s procedure.[89] Justice Hotten asserted that the majority appeared “to conflate the role of the trial judge as gatekeepers, with the evaluation of the science or the expert opinion that is presented for consideration of its admissibility by the judge.”[90] Joining in that dissent was Justice Angela Eaves, who was elevated to the Court in 2022 after serving as a trial judge for twenty-two years.[91]
Justice Gould issued a separate dissent asserting that the Majority had abandoned the abuse-of-discretion standard:
[T]he Majority simply disagrees with the trial court’s application of the Daubert factors and its interpretation of the evidence—a classic de novo review. If the abuse of discretion standard is not appropriate here, then we should reconsider whether that standard is appropriate for reviewing Daubert decisions. But we do not serve well the parties and trial judges who apply our decisions if we inconsistently apply the standards of review to a trial court’s discretionary ruling.[92]
B. The Oglesby Decision (Lead Paint)
Unlike Abruquah, the Supreme Court of Maryland was unanimous in Oglesby v. Baltimore School Associates.[93] Justice Watts authored the Oglesby opinion after dissenting in Rochkind, Frankel, and Matthews, and joining the Abruquah majority.[94]
Oglesby addressed the admissibility of expert testimony from a pediatrician, Dr. Steven Caplan, in a case alleging injury from childhood exposure to lead paint.[95] There, Dr. Caplan’s expert testimony provided that plaintiff’s “likely exposure to lead at the [defendant’s] property was a significant contributing factor to bringing about [plaintiff’s] cognitive deficiencies and impairments . . . and to a loss of approximately 3 to 4 IQ points.”[96] The trial court had held a Frye-Reed hearing in 2020 shortly before Rochkind was decided.[97] In a difficult-to-follow series of oral rulings, the trial court found that Dr. Caplan’s opinion lacked a sufficient factual basis to be reliable.[98] The Appellate Court of Maryland affirmed, holding that “the disputed nature of the evidence regarding the presence of lead in [the apartment], the disputed nature of the evidence regarding [plaintiff’s] exposure to peeling paint, and the disputed nature of the evidence regarding any injury suffered as a result” led to its decision.[99]
Reversing, the Supreme Court of Maryland held that the plaintiff had “produced more than sufficient evidence that lead was present in the building . . . , that she was exposed to lead-based paint at the property, and that the property was a source of her elevated [blood lead levels]’s opinions.”[100] The Court held that “[c]ausation in lead-based paint cases may be proven by showing that the defendant’s negligence was a ‘substantial factor’ in causing the plaintiff’s injury.”[101] Notably, the substantial-factor test did not require Dr. Caplan to rule out exposure at other properties.[102] Credibility of contested testimony about lead-paint exposure at other properties was “a matter for the trier of fact to determine, not the circuit court in ruling on the motion to preclude.”[103] The Court held that “given the large quantity of data that he had available and reviewed and the nature of the challenge to the admissibility of his testimony, a remand for further proceedings as to Dr. Caplan’s opinion that [plaintiff’s] exposure to lead at the property was a substantial contributing factor to her injuries (other than IQ loss) is not warranted.”[104] In other words, no Rochkind hearing was necessary on this aspect of Dr. Caplan’s testimony because it would have been an abuse of discretion for the trial court to sustain the defendant’s objection.
Still, remand was necessary for a Daubert hearing on Dr. Caplan’s testimony about plaintiff’s IQ loss.[105] Dr. Caplan relied on two studies, and under established law, an expert could rely on one of them to “offer an opinion that exposure to lead resulted in a specific loss of IQ points.”[106] But “neither Dr. Caplan’s report nor his deposition testimony fully explains the basis for his calculations under either study.”[107] A Daubert hearing was appropriate “to assess Dr. Caplan’s use of the studies and the reliability of his methodology” on that issue.[108] Like Frankel, the Court concluded that “in light of the findings made by the trial judge in ruling on the motions, this case should be assigned to a different trial judge for all further proceedings.”[109]
C. The KatzAbosch Decision (Lost Profits)
The appeal in Katz, Abosch, Windesheim, Gershman & Freedman, P.A. v. Parkway Neuroscience & Spine Institute, LLC, produced four opinions: Justice Biran’s opinion for the Court, a concurring opinion by Justice Booth, a partial dissent by Justice Gould, and a dissent by Justice Watts.[110]
A medical practice sued an accounting firm for alleged malpractice.[111] Without reaching the merits of the allegations of accounting malpractice, the trial court excluded the medical practice’s lost profits expert, Megan Cardell, leading to summary judgment for lack of proof of the essential element of damages.[112] After the Appellate Court of Maryland reversed the Daubert ruling, the Supreme Court granted certiorari.[113]
The Court began by observing that it had “asked judges to engage with the science without playing amateur scientist, and . . . promised the deference appropriate to courts administering a flexible approach to analyzing the admissibility of expert testimony.”[114] Holding that the trial court’s analysis mostly fell within its discretion, the Court explained that “the choice or calculation of the inputs to a methodology can be a part of the methodology itself,” rejecting “an unduly rigid dividing line between ‘data’ and ‘methodology’ that binds courts to admit methodologically questionable analyses cloaked as data.”[115] The Court found the trial court’s Daubert-Rochkind analysis proper to “the extent the trial court considered how [] Cardell’s choice of data, assumptions, and other inputs affected the reliability of her methodology[.]”[116]
Even so, the Court held that the trial court exceeded its discretion in one respect. Shortly before the Daubert hearing, Cardell amended her lost-profits analysis to make “normalizing adjustments[.]”[117] The Court noted that while “the information that led to these adjustments had long been available to her, [] Cardell explained that she looked again at the numbers ahead of the Daubert-Rochkind hearing and identified a payment that looked like it belonged to a different year.”[118] The trial court had erroneously viewed Cardell’s “updates, which the court discussed in the context of Daubert–Rochkind factors three (known or potential rate of error) and 10 (whether the field of expertise is known to reach reliable results for the projected type of expert opinion), as implicating the reliability of her methodology.”[119] Then, the trial court “was troubled by the timing of [] Cardell’s updates—without new information and ‘for fully subjective reasons’—which, the [trial] court believed, reflected negatively on her methodology.”[120]
The Court instead held “there was new information of a sort: [] Cardell noticed something she had not noticed before on first examination.”[121] Drawing an analogy to a more familiar Rule 5-702 area of expertise, the Court noted that Cardell “sought clarification and revised her opinion, just as a doctor might order a biopsy and diagnose a patient with skin cancer if the doctor had missed a mole upon first examination of the patient.”[122] A doctor suddenly “[c]atching something peculiar the second time around neither undermines the adequacy of the data (the patient’s skin) nor the court’s understanding of the expert’s methodology (examining the patient’s skin for disease indicators).”[123] “At most,” the Court held, Cardell’s revisions “went to the care with which she applied her methodology, which is a matter to be explored on cross-examination before the jury (if [] Cardell’s testimony is otherwise found to be sufficiently reliable).”[124]
In a disposition different from any of its prior Daubert cases, the Court ordered “a limited remand to the circuit court under Maryland Rule 8-604(d)(1) so that the trial court may decide to admit or exclude [] Cardell’s testimony without consideration of her [pre-hearing] normalizing adjustments as reflecting on the reliability of [] Cardell’s methodology.”[125] Rather than vacate the judgment, the Court decided to remand and “retain jurisdiction,” which permitted the Court to “issue an appropriate Order” after the trial court reached a decision.[126]
Two justices disagreed with that disposition. Justice Gould agreed “that [] Cardell’s updated calculations and her reasons for them do not go to the reliability of her methodology, but are instead grist for the cross-examination mill.”[127] Nevertheless, Justice Gould thought it unnecessary to “remand for the trial court to reconsider its analysis,” because “Cardell’s methodology is so fundamentally flawed as to constitute ‘the rare case’ in which a trial court’s admission of expert testimony would have been an abuse of discretion.”[128] Likening Cardell’s opinion to “a lost profits analysis of a gas station [that] failed to account for changes in the wholesale and retail prices of gasoline,” Justice Gould believed “Cardell’s failure to make any attempt to account for . . . confounding variables requires the exclusion of her testimony.”[129] Taking a diametrically opposite view, Justice Watts dissented in full, believing that “in assessing the reliability of [Cardell’s] methodology, the circuit court abused its discretion by determining that choices of data and other inputs rendered her methodology unreliable.”[130]
Joining in the Court’s opinion, Justice Booth penned a concurrence that, as a prominent Daubert commentator noted, “might prove the most influential and enduring.”[131] Justice Booth wrote “to respond to the Majority’s invitation to ‘reflect on [the] flexibility and deference’ due to courts analyzing the admissibility of expert testimony.”[132] She addressed how the Court’s “post-Rochkind batting average” did not align with its prediction in Matthews that reversal would be only in the “rare case:”[133]
I was one of the members of this Court who voted in Rochkind to adopt the Daubert standard. I joined the majority opinions written by my colleagues in Matthews, Abruquah, Oglesby, and the instant case, and I agree with our analysis in each of them. That said, with some time to reflect on the Court’s application of the abuse of discretion standard in the context of appellate review of a trial court’s decision to admit or deny expert testimony in its consideration and application of the Daubert-Rochkind factors, I have some unease about our recitation of our traditional abuse of discretion formulation, which we developed and apply in other contexts. I observe that this formulation appears to be inconsistent with the abuse of discretion standard employed by the federal courts in the Daubert context, as well as the careful and searching examination that this Court is conducting in reviewing these cases …. I believe that when this Court applies abuse of discretion when reviewing expert witness admissibility determinations, we should articulate an abuse of discretion standard that is in line with the federal courts’ formulation and that reflects this Court’s current practice. When we adopted the Daubert standard, we adopted it in full. That necessarily includes the federal courts’ application of the abuse of discretion standard.[134]
Although “the abuse of discretion standard is typically considered to be the most deferential,” the standard “has been described as ‘famously slippery,’ and has been understood to have different meanings and applications in different contexts.”[135] One Justice “wrote that ‘the variety of subjects left to discretionary decision requires caution in synthesizing abuse of discretion cases.’”[136] Second Circuit Judge Henry J. Friendly observed that “appellate courts ‘must carefully scrutinize the nature of the trial court’s determination and decide whether that court’s superior opportunities of observation or other reasons of policy require greater deference than would be accorded to its formulations of law or its application of law to the facts.’”[137]
Justice Booth cited commentary collecting “examples of federal circuit courts conducting ‘searching’ reviews of admissibility determinations in the expert witness context” that resembled de novo review.[138] Such scrutiny “feels out of sync with the even more deferential approach that we take when reviewing other types of discretionary decisions by trial courts and our ‘no reasonable person’ and ‘well removed from the center mark’ articulation of the standard.”[139]
Justice Booth quoted extensively from a Tenth Circuit decision holding that an appellate court will “review de novo the question of whether the [trial] court applied the proper standard and actually performed its gatekeeper role in the first instance,” and only “then review the trial court’s actual application of the standard in deciding whether to admit or exclude an expert’s testimony for abuse of discretion.”[140] When an opponent objects to admissibility of an expert’s testimony, the trial “court must adequately demonstrate by specific findings on the record that it has performed its duty as gatekeeper.”[141] Such specific findings are necessary to ensure the trial “court carefully and meticulously reviewed the proffered scientific evidence or simply made an off-the-cuff decision to admit the expert testimony. In the absence of such findings, we must conclude that the court abused its discretion in admitting such testimony.”[142]
Similarly, the “Seventh Circuit describes a ‘two-step standard of review in cases challenging a [trial] court’s admission or exclusion of the testimony of an expert.’”[143] De novo review governs whether the trial court properly applied the Daubert framework, and, if so, abuse-of-discretion review governs the ultimate ruling on admissibility.[144] Or, as the Eleventh Circuit summarized, an “abuse of discretion can occur where the [trial] court applies the wrong law, follows the wrong procedure, bases its decision on clearly erroneous facts, or commits a clear error in judgment.”[145]
On limited remand in KatzAbosch, the trial court issued a new opinion that “removed from any consideration Cardell’s June 2021 normalization,” and again excluded the testimony, which it still viewed “as speculative and containing unreliable and ipse dixit ‘judgment calls.’”[146] In its continuing exercise of jurisdiction, the Court ordered the Appellate Court to affirm the trial court’s judgment.[147]
III. Categories of Daubert Error
Justice Booth’s concurrence hinted at a problem I encountered when briefing KatzAbosch. Few appellate decisions and secondary sources have wrestled with the abuse-of-discretion standard in the Daubert context, and how that standard differs from other discretionary contexts.
Surveying the grounds for reversal or vacatur in the Abruquah-Oglesby-KatzAbosch trilogy, appellate review of Daubert rulings is not significantly different from other discretionary rulings. Oglesby and KatzAbosch found errors in the interpretation of Rule 5-702, which now includes the Daubert factors.[148] Such interpretive issues are always subject to de novo review.[149] Abruquah adopted a new boundary on trial courts’ discretion, similar to decisions setting new boundaries on trial judges’ discretion in questioning prospective jurors.[150] The authority to set boundaries on discretion derives from the Court’s plenary constitutional rulemaking power, and its statutory certiorari power to promote uniformity in rules of decision.[151] In boundary-setting cases, the trial court’s exercise of discretion does not constrain the Court’s power.
A. Procedural Error
When legal error affects the framework, it is more accurate to say that the circuit court made a threshold procedural error subject to de novo review, not that there has been an abuse of discretion. Although evidentiary rulings are reviewed for abuse of discretion generally, the interpretation of the rules of evidence remains a legal question reviewed de novo.[152]
“There is a difference . . . between how a trial court makes its decision and what decision it makes.”[153] For example, when a statute makes a fee award discretionary, the “standard that a trial court applies in evaluating whether to award attorneys’ fees and costs is a legal decision,” so only “the conclusion that the court arrives at after applying that standard to the facts of the particular case is an exercise of discretion.”[154] Thus, whether the trial court has applied proper or improper factors is “a question of law” reviewed “without deference to the trial court.”[155] Or, when a trial court imposes a criminal sentence, its broad discretion does not allow it to consider improper factors.[156] Similarly, when making a discretionary decision on a motion for discovery sanctions, “the trial judge is required to consider every aspect of the case and then choose the most appropriate remedy.”[157]
Oglesby involved two threshold legal errors. First, the trial court misunderstood the directive in Rule 5-702 that “the court shall determine . . . whether a sufficient factual basis exists to support the expert testimony.”[158] This provision does not authorize a trial court to resolve fact witnesses’ credibility, which is the jury’s province.[159] Second, to the extent the trial court agreed with the landlord’s argument that the expert failed to rule out alternative sources of exposure to lead paint,[160] it misinterpreted the rule’s requirement that “the testimony will assist the trier of fact to understand the evidence or to determine a fact in issue.”[161] The “substantial factor” test for lead-paint injury does not require the jury to rule out other potential sources.[162]
The partial error in KatzAbosch was also a misreading of Rule 5-702. The Daubert factors are part of “interpreting Rule 5-702.”[163] Although the Daubert factors are flexible, the trial court misinterpreted them in finding that the expert’s updates, without new information, “reflected negatively on her methodology.”[164] An expert can and should update their opinion if they realize they missed something.[165] Such a change is grist for cross-examination, not Daubert “gatekeeping.”[166]
Ultimately, as part of its procedural obligations, a trial court must explain its decision in sufficient detail to show that it exercised discretion and enable meaningful appellate review.[167]
B. Substantive Error
When a trial court properly adheres to the Daubert framework, substantive review is deferential. Reversal is appropriate in two main categories. The first is “when all proper and no improper factors are assessed, but the [trial] court makes a serious mistake in weighing them.”[168] The second is when the Supreme Court of Maryland, exercising its discretionary power to set uniform rules of decision, draws boundaries on trial courts’ Daubert discretion.
Abruquah fell into the latter category, setting a new boundary on discretion rather than finding an abuse of discretion in the traditional sense. In a footnote, the Court observed it “has frequently described an abuse of discretion as occurring when ‘no reasonable person would take the view adopted by the circuit court’ or when a decision is ‘well removed from any center mark imagined by the reviewing court and beyond the fringe of what the court deems minimally acceptable.’” [169] But the Court thought it “somewhat unfair” to apply “those descriptions to a trial court’s application of a newly adopted standard.”[170] The “circuit court acted deliberately and thoughtfully in approaching, analyzing, and resolving the question before it,” but the “Court’s majority has come to a different conclusion concerning the outer bounds of what is acceptable expert evidence in this area.”[171]
Although the Abruquah dissenters saw this “unfair” language as proof the Court was overstepping its appellate role,[172] the Court’s holding is best understood as an exercise of its statutory and constitutional authority to set uniform rules of procedure. This function draws on the Court’s constitutional power to adopt and amend rules of practice and procedure—including the rules of evidence.[173] The function also draws on the Court’s discretionary certiorari power to promote statewide uniformity.[174] Even before 1966, when Maryland had no intermediate appellate court and the Court heard appeals from the circuit courts by right,[175] the Court had discretionary certiorari jurisdiction to “secure uniformity of decision” when the circuit courts heard appeals in misdemeanor cases despite no further appeal by right existing.[176]This uniformity-of-decision language is absent from the statute granting the Court certiorari power to review cases decided by—or pending in—the Appellate Court when “desirable and in the public interest.”[177] Still, “divided opinions in the same circuit court or between circuit courts in Maryland” remain grounds to exercise that discretion.[178] As the Supreme Court of United States has explained, the modern writ of certiorari helps avoid “unfortunate confusion in respect to the rules of . . . decision.”[179]
Implicit in abuse-of-discretion review is that “[s]ome inconsistency is inevitable,” as different trial courts could reach different conclusions on the same record.[180] When adopting Daubert, the Court determined that a “marginal amount of inconsistency” was an acceptable cost in moving away from Frye-Reed.[181]
In the same vein, the Court has discretion to decide when—in its judgment—the costs of inconsistency outweigh the benefits of broad discretion, and it therefore becomes necessary to security uniformity of decision. Rochkind was not the Court’s most controversial 2020 change affecting trial judges’ discretion under the Maryland Rules. That distinction belongs to Kazadi v. State,[182] in which the Court’s four-to-three majority reversed a 1964 precedent holding it “inappropriate” to ask prospective jurors whether they could follow instructions about the presumption of innocence in criminal cases.[183] Rule 4-312 grants trial judges discretion over what questions they ask prospective jurors.[184] In Kazadi, the Court noted that the Maryland State Bar Association’s Special Committee on Voir Dire had “recommended asking during voir dire whether any prospective jurors cannot honor the presumption of innocence, and noted that, though ‘not required,’ that voir dire question is ‘widely used.’”[185] Making such questions “mandatory on request,” the Court sought to “ensure . . . that all defendants—not just ones whose trials are presided over by circuit court judges who chose to exercise the discretion to grant requests to ask such voir dire questions,” could “move to strike prospective jurors for cause on the ground of an unwillingness or inability to adhere to these fundamental rights.”[186]
Similarly, amid the controversy over ballistics testimony, Abruquah ensures that the limits on such evidence—with great power to persuade jurors—will not depend on the fortuity of which trial judge happens to hear a case. The risk of inconsistency was even higher in Abruquah, because many gun-related prosecutions can be brought in federal court.[187] Because of Daubert rulings from Maryland federal judges that have limited ballistics testimony,[188] the inconsistency would risk the rights of a Maryland defendant turning on whether state or federal prosecutors brought charges.
As the dissenting opinions in Abruquah show, such boundary-setting often will require the Court to wade into controversy and expose the justices to criticism that they are playing “amateur scientists.”[189] Whenever a certiorari court resolves a division of authority in any area of law, it is taking sides after reasonable minds have differed and has decided that the benefits of uniformity outweigh the risk it might be taking the wrong side. That risk was mitigated in Abruquah, however, because the Court was relying on thorough Daubert rulings by Judge Grimm, a highly regarded judge.[190] It would be hard to go wrong following the lead of a jurist with Judge Grimm’s expertise when the Court exercises its power to secure uniformity throughout Maryland trial courts.
Such a survey of persuasive authority, to decide the best rule for Maryland on a recurring question, is a legal question of the sort the Court decides de novo.[191] Maryland’s constitution and laws give the Court considerable discretion in both when and how it imposes uniformity in the rules of decision.[192] For example, when determining whether to alter discretionary voir dire questioning, the Court can either address a proposal made through the Standing Committee on Rules of Practice and Procedure[193] or it can exercise certiorari review when a litigant’s appeal presents a vehicle to decide the question.[194] Each path has its advantages and disadvantages; but the Court’s authority is no less broad on certiorari review than when it considers rule amendments.[195] Similarly, upon the release of the 2009 and 2016 reports cited in Abruquah, the Court could have considered Rule 5-702 amendments that, perhaps through committee notes, embraced Daubert and directed trial courts to place careful limitations on techniques like the AFTE Theory.[196] Instead, the Court waited for a case showing how the AFTE Theory affected an individual defendant’s rights and followed persuasive authority to draw a boundary.[197] Hearing this question in an individual case did not undermine the Court’s plenary authority to write such boundaries into Rule 5-702 through case law.
A recent rule change may prove particularly valuable when litigants ask the Court to draw new boundaries on Daubert discretion. Most of the Appellate Court’s opinions are unreported, and until 2023, it was forbidden to cite such unreported opinions as precedential or even as persuasive.[198] Under an amendment to Rule 1-104, an “unreported opinion issued on or after July 1, 2023 may be cited for its persuasive value only if no reported authority adequately addresses an issue before the court.”[199] The 2023 amendment also clarified that unreported decisions from federal courts and other states “may be cited as persuasive authority if the jurisdiction in which the opinion was issued would permit it to be cited as persuasive authority or as precedent.”[200] These changes increase the range of persuasive authority trial courts may consult on Daubert rulings; these cases should aid in developing a robust body of rulings in Maryland. When the Appellate Court decides a Daubert appeal in an unreported opinion, the Court may decide it is not yet “desirable and in the public interest” to exercise its certiorari power to weigh in on the issue.[201] When the Court denies a petition for certiorari from an unreported opinion, it will signal to the circuit courts they remain free to reach different conclusions in exercising Daubert discretion. And when the Court is satisfied that the law is sufficiently developed inside or outside Maryland, or that the issue is otherwise too important for trial judges to reach divergent conclusions, it may issue certiorari to decide the boundaries of trial courts’ Daubert discretion.
Outside of such boundary-setting cases, review is much closer to the traditional abuse-of-discretion formulation. It may be somewhat more searching than in other contexts—like sentencing. For example, the Court held in Oglesby that, putting aside the trial court’s impermissible credibility determinations, the expert’s substantial-factor opinion had a manifestly sufficient factual basis, and the trial court lacked discretion to find otherwise.[202] Therefore, remand was unwarranted on that issue, but the trial court still had discretion as to the expert’s further opinion on the plaintiff’s IQ loss.[203]
Still, when the trial court has considered all relevant factors and no irrelevant factors, reversal should indeed be the rare case.
C. Harmless Error
No survey of appellate review is complete without a discussion of harmless error. The Court explained in Abruquah that the “harmless error doctrine is grounded in the notion that a defendant has the right to a fair trial, but not a perfect one.”[204] In a criminal case, for “an appellate court to conclude that the admission of expert testimony was harmless, the State must show ‘beyond a reasonable doubt, that the error in no way influenced the verdict.’”[205] The Court held that the State failed to meet this burden in Abruquah.[206] Although the circumstantial evidence of guilt was strong, the ballistics expert’s testimony was the only direct evidence.[207] By contrast, a civil appellant bears the burden of showing that an error was prejudicial to the outcome.[208]
KatzAbosch recognized a similar concept: an appellate court may conclude that an error in a Daubert analysis does not require a remand if the error did not affect the overall analysis.[209] In ordering a partial remand, the Court was careful to not “suggest that, in every case where an appellate court concludes that part of a trial court’s Daubert ruling was based on proper factors and another part was not, a limited remand to the trial court is necessary.”[210] The Court predicted that “in many cases, it will be clear from the record whether the trial court would have admitted or excluded the expert testimony without consideration of a factor that is later determined to have been improper on appeal.”[211] It encouraged “trial courts to make such matters explicit on the record when possible.”[212] Thus, it was only in a footnote in KatzAbosch that held that the trial court “also erred when it stated that [the] lost-profit calculations would not be helpful to the jury,” because the trial court was also clear that “its finding with respect to helpfulness was a ‘very, very slight factor’ in its decision to exclude [the] testimony.”[213] It appears that, had the “very, very slight factor” been the only error, no remand would have been necessary for the Court to affirm.[214]
IV. The Benefits of Avoiding Unnecessary “Abuse of Discretion” Holdings
It is no secret that the Daubert transition has led to some tension between trial and appellate courts. The three Rochkind dissenters all served as trial judges under the Frye-Reed regime.[215] To be sure, trial judges are not monolithic, and some have welcomed Daubert. Judge Adkins, who championed adopting Daubert, was a former trial judge.[216] At minimum—as Rochkind recognized in another quote from Judge Grimm—the shift to Daubert made trial judges’ jobs harder in the short term:
[J]udges, lawyers and expert witnesses will have to learn to be comfortable refocusing their thinking about the building blocks of what truly makes evidence that is beyond the knowledge and experience of lay persons useful to them in resolving disputes. The beneficiaries of this new approach will be the jurors that have to decide increasingly complex cases. Daubert, Kumho Tire, and now Rule 702 have given us our marching orders, and it is up to the participants in the litigation process to get in step.[217]
The Court alluded to these tensions in Abruquah when it noted it was “somewhat unfair” to say “no reasonable person would take the view adopted by the circuit court” or that the decision was “well removed from any center mark imagined by the reviewing court and beyond the fringe of what the court deems minimally acceptable,” when the trial court was applying the new standard of review.[218]
It is not just “somewhat unfair,” but unnecessary, for an appellate court to say a trial court abused its discretion when a decision turns on threshold procedural error or when the Court sets a new boundary on discretion. When legal error infects a discretionary decision, one way to phrase the reversal is that “a failure to consider the proper legal standard in reaching a decision [, which] constitutes an abuse of discretion.”[219] Stated differently, however, is that the “standard that a trial court applies . . . is a legal decision,”[220] which is subject to de novo review,[221] and that only “the conclusion that the court arrives at after applying that standard to the facts of the particular case is an exercise of discretion.”[222]
Trial judges take great pride and care in their work, and they are doing their best to “get in step” with Daubert-Rochkind.[223] It may seem like a step backward to say portions of the Daubert analysis are subject to de novo review, after Rochkind touted that instead “of maintaining two separate, and potentially outcome determinative, standards of review—de novo for Frye–Reed and abuse of discretion for Rule 5-702—all expert testimony is reviewed under the abuse of discretion standard.”[224] But interpreting any rule of evidence is a legal question reviewed de novo.[225] When it is unnecessary to say a trial court abused its discretion—with its somewhat harsh connotations—there is reason for a reviewing court to avoid such language.
V. Conclusion
It is both possible and beneficial to harmonize the Supreme Court of Maryland’s decisions in Matthews, Abruquah, Oglesby, and KatzAbosch, and to distill a nuanced standard of Daubert review. As with any evidentiary ruling, an appellate court reviews de novo whether the trial court’s ruling reflected a legally correct interpretation of the applicable rule. Rule 5-702, which incorporates the Daubert framework, is no different. If the trial court follows the correct procedure, abuse-of-discretion review governs the trial court’s weighing of the Daubert factors. At that stage of the inquiry, it indeed should be a rare case in which the appellate court finds a substantive error so serious as to fall outside the trial court’s broad discretion. Still, that discretion is subject to the Supreme Court of Maryland’s power to set the outer bounds of discretion, particularly when the Court determines that the interest in uniform rules of decision outweighs the policy of deference to the trial court’s discretion. Just as trial courts should be clear in their Daubert findings, appellate courts should be clear as to the nature of review when vacating or reversing a Daubert ruling.
Steven M. Klepper chairs the appellate practice group at Kramon & Graham, P.A. He co-edits Paul M. Sandler, Andrew D. Levy & Steven M. Klepper, Appellate Practice for the Maryland Lawyer: State and Federal (6th ed. 2023). Steve founded the Maryland Appellate Blog in 2013 and has since served as the editor-in-chief. He co-founded the Cole-Davidson American Inn of Court and is its President-Elect. The Maryland State Bar Association’s Section of Litigation named him Litigator of the Year in 2024.
[1] Rochkind v. Stevenson, 471 Md. 1, 38 (2020) (“[W]e adopt the Daubert standard in Maryland because we find those factors persuasive in interpreting Maryland Rule 5-702.”).
[2] State v. Matthews, 479 Md. 278, 305 (2022).
[3] Katz, Abosch, Windesheim, Gershman & Freedman, P.A. v. Parkway Neuroscience & Spine Inst., LLC, 485 Md. 335, 384 (2023); Oglesby v. Balt. Sch. Assocs., 484 Md. 296, 361–62 (2023); Abruquah v. State, 483 Md. 637, 698 (2023); see infra Part II. Although this article draws on my research and briefs from representing the KatzAbosch petitioners, I speak only for myself and not for any client or my firm.
[4] KatzAbosch, 485 Md.at 387 (Booth, J., concurring).
[5] See infra Section III.A.
[6] Id.; see also Harvey Brown, Procedural Issues Under Daubert, 36 Hous. L. Rev. 743, 1134 (1999).
[7] Young v. State, 234 Md. App. 720, 731 (2017).
[8] I use the singular “they” as a pronoun encompassing all genders. The capitalized word “Court” refers to the Supreme Court of Maryland, and “Appellate Court” refers to the Appellate Court of Maryland. Effective December 14, 2022, the Court of Appeals of Maryland was renamed the Supreme Court of Maryland, and the Court of Special Appeals was renamed the Appellate Court of Maryland. Like those courts, I use the current names retroactively, but I use the title “Justice” only for jurists who held that title during active service after the 2022 amendment took effect. See A Conversation with The Honorable Chief Justice Matthew J. Fader, Supreme Court of Maryland, in Paul M. Sandler, Andrew D. Levy & Steven M. Klepper, Appellate Practice for the Maryland Lawyer: State and Federal 23, 24–25 (6th ed. 2023).
[9] See infra Section III.B.
[10] Rochkind v. Stevenson, 471 Md. 1, 4 (2020).
[11] Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).
[12] Reed v. State, 283 Md. 374 (1978).
[13] Rochkind, 471 Md. at 4 (quoting Reed, 283 Md. at 381).
[14] Id. at 5 (quoting Savage v, State, 455 Md. 138, 187 (Adkins, J., concurring))..
[15] See generally Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993).
[16] Id. at 587; see also Act to Establish Rules of Evidence, Pub. L. No. 93–595, 88 Stat. 1926 (1975).
[17] Daubert, 509 U.S. at 588 (quoting Fed. R. Evid. 702 (1975) (amended 2000)).
[18] Id. at 589.
[19] Rochkind v. Stevenson, 471 Md. 1, 5 (2020).
[20] Id.
[21] Id.
[22] Id. at 21 (quoting Md. Rule 5-702 (1994) (amended 2021)).
[23] Id. at 21–22 (quoting Md. Rule 5-702 advisory committee’s note to 1994 amendment) (citing Burral v. State, 352 Md. 707, 738 (1999)).
[24] See generally Blackwell v. Wyeth, 408 Md. 575 (2009); see also Savage v. State, 455 Md. 138 (2017).
[25] Blackwell, 408 Md. at 604.
[26] Id. at 606 (internal citations omitted).
[27] Id. at 608 (“Generally, accepted methodology, therefore, must be coupled with generally accepted analysis in order to avoid the pitfalls of an ‘analytical gap.’”).
[28] Id. at 611.
[29] Id. at 611–12.
[30] Id. at 630.
[31] Savage v. State, 455 Md. 138, 184–85 (2017) (Adkins, J., concurring).
[32] Id. at 184.
[33] Id.
[34] Rochkind v. Stevenson, 471 Md. 1, 30 (2020).
[35] See id. at 5–10.
[36] Id. at 10.
[37] Id. at 26, 30.
[38] Id. at 30.
[39] Id. at 31 (quoting United States v. Horn, 185 F. Supp. 2d 530, 553 (D. Md. 2002)).
[40] Rochkind, 471 Md. at 31 (quoting Horn, 185 F. Supp. at 553).
[41] Id. at 31–32 (quoting Horn, 185 F. Supp. at 553).
[42] Id. at 35–36 (quoting Fed. R. Evid. 702 advisory committee’s note to 2000 amendment) (pronouns modified).
[43] Id. at 37 (emphasis omitted).
[44] Judge Robert McDonald, Justice Brynja Booth, and Justice Jonathan Biran joined Chief Judge Joseph Getty’s majority opinion, whereas Justice Michele Hotten and Judge Clayton Greene joined Justice ShirleyWatts’s dissent. Compare Rochkind, 471 Md. at 4, with Rochkind, 471 Md. at 39 (Watts, J., dissenting). Judges serving on Maryland’s highest court are now referred to as Justice because of the Court of Appeals’ transformation into the Supreme Court of Maryland in 2022. Ali Mahdi, Election Day was a “Namechanger”: Voters Successfully Rename Maryland’s Appellate Courts, U. Balt. L. F. Blog (Nov. 13, 2022), https://ublawforum.com/2022/11/13/election-day-was-a-namechanger-voters-successfully-rename-marylands-appellate-courts/.
[45] Chief Judge Joseph Getty was a dedicated public servant in Maryland before he was appointed to the Maryland Court of Appeals on June 27, 2016. See Appointments by Governor, 1996–2004, Md. Manual On-Line (July 31, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/apappoint.html. Chief Judge Getty served as the Governor’s Chief Legislative Officer directly before his appointment. Joseph M. Getty,Md. Manual On-Line (Nov. 6, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/former/html/msa12229.html.He also represented Marylanders in the General Assembly’s House of Delegates—1995 to 2003—and Senate—2011 to 2015. Id.
Justice Jonathan Biran was appointed to the Maryland Court of Appeals on December 6, 2019. See Appointments by Governor, 1996–2004, Md. Manual On-Line (July 31, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/apappoint.html. Before Justice Biran was a shareholder at Baker Donelson—2018 to 2019—and a partner at Rifkin Weiner Livingston LLC—2018—and Biran Kelly LLC—2013 to 2017—Justice Biran was an Assistant U.S. Attorney for the District of Connecticut—2000 to 2006—and District of Maryland—2006 to 2013. Jonathon Biran, Md. Manual On-Line (Apr. 11, 2025), https://msa.maryland.gov/msa/mdmanual/29ap/html/msa18245.html.
Justice Brynja Booth was appointed to the Maryland Court of Appeals on March 12, 2019. See Appointments by Governor, 1996–2004, Md. Manual On-Line (July 31, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/apappoint.html. Before Justice Booth founded and practiced at Booth, Booth, Cropper & Marriner—2015 to 2019—she practiced at Cowdrey, Thompson & Karsten, P.C.—1997 to 2015. Brynja McDivitt Booth, Md. Manual On-Line (Oct. 16, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/msa18104.html.
Judge Robert McDonald was appointed to the Maryland Court of Appeals on January 24, 2012. See Appointments by Governor, 1996–2004, Md. Manual On-Line (July 31, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/apappoint.html. Judge McDonald was an associate at Foley, Hoag & Eliot—1978 to 1979—prior to serving as an Assistant U.S. Attorney for the District of Maryland—1980 to 1988—and working for Maryland’s Office of Attorney General—1989 to 2012. Robert N. McDonald, Md. Manual On-Line (Nov. 6, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/former/html/msa11507.html.
[46]Judge Clayton Greene, Jr. was appointed to the Maryland Court of Appeals on January 22, 2004. See Appointments by Governor, 1996–2004, Md. Manual On-Line (July 31, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/apappoint.html. Judge Greene was an assistant county solicitor—1977 to 1978—prior to serving as an Assistant Public Defender—1978 to 1985—and Deputy Public Defender for Anne Arundel County—1985 to 1988. Clayton Greene, Jr., Md. Manual On-Line (Oct. 4, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/former/html/msa12365.html. Judge Greene was then appointed to the state bench in 1990 as an Administrative Judge in the District Court of Maryland, District 7, Anne Arundel County and to the Circuit Court for Anne Arundel County before serving on the Maryland Court of Appeals. Id.
Justice Michele D. Hotten was appointed to the Maryland Court of Appeals on December 1, 2015. See Appointments by Governor, 1996–2004, Md. Manual On-Line (July 31, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/apappoint.html. Justice Hotten started as an Assistant State’s Attorney for Prince George’s County and then worked as associate at Farrington, Smallwood, Wells & Wyrough—1989 to 1992—before working as a solo practitioner—1992 to 1994—while serving in several part-time roles. Michele D. Hotten, Md. Manual On-Line (July 8, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/former/html/msa12366.html. Thereafter, Justice Watts was appointed as an Associate Judge for the District Court of Maryland, District 5, Prince George’s County in 1994, the Circuit Court for Prince George’s County in 1995, and the Maryland Court of Special Appeals in 2010 before serving on the Maryland Court of Appeals. Id.
Justice Shirley M. Watts was appointed to the Maryland Court of Appeals on July 3, 2013. See Appointments by Governor, 1996–2004, Md. Manual On-Line (July 31, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/apappoint.html. Justice Watts began as an Assistant State’s Attorney—1984 to 1988—before becoming an Assistant Federal Public Defender—1990 to 1994—and a Supervisory Assistant Federal Public Defender in the District of Maryland. Shirley M. Watts, Md. Manual On-Line (Oct. 16, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/msa13752.html. After working for the Social Security Administration in California and Pennsylvania, Justice Watts was appointed to the Circuit Court of Baltimore City in 2002 and the Court of Special Appeals in 2011 before serving on the Maryland Court of Appeals. Id.
[47] Rochkind v. Stevenson, 471 Md. 1, 38–39 (2020) (quoting Kazadi v. State, 467 Md. 1, 47 (2020)) (internal quotation marks omitted).
[48] See generally Frankel v. Deane, 480 Md. 682 (2022).
[49] Id.
[50] Id. at 696.
[51] Id. at 704.
[52] Id. at 714–15.
[53] Id. at 715–16 (Watts, J. dissenting).
[54] Frankel, 480 Md. at 715–16.
[55] State v. Matthews, 479 Md. 278, 284 (2022).
[56] Id. at 285.
[57] Id.
[58] Id. at 292.
[59] Id.
[60] Id. at 304 (citing Matthews v. State, 249 Md. App. 509, 543–44 (2021)).
[61] Matthews, 479 Md. at 305.
[62] Id. (internal citations omitted).
[63] Id. at 313.
[64] Id.
[65] Id. at 286, 306 (“Post-Rochkind, it is still the rare case in which a Maryland trial court’s exercise of discretion to admit or deny expert testimony will be overturned.”).
[66] Id. at 327 (Watts, J., dissenting).
[67] Matthews, 479 Md. at 327 (Watts, J., dissenting).
[68] Katz, Abosch, Windesheim, Gershman & Freedman, P.A. v. Parkway Neuroscience & Spine Inst., LLC, 485 Md. 335, 384 (2023); Oglesby v. Balt. Sch. Assocs., 484 Md. 296, 361–62 (2023); Abruquah v. State, 483 Md. 637, 698 (2023).
[69] KatzAbosch, 485 Md. at 384; Oglesby, 484 Md. at 361–62; Abruquah, 483 Md. at 698.
[70] Abruquah, 483 Md. 637, 648.
[71] Id. at 647–48 (quoting Fleming v. State, 194 Md. App. 76, 100–01 (2010)).
[72] Id. at 649.
[73] Id. at 651.
[74] Id.
[75] Abruquah, 483 Md.at 651.
[76] Id. at 652.
[77] Id. at 698.
[78] Id. at 662.
[79] Id. at 663–64.
[80] Id. at 665 (quoting Executive Office of the President, President’s Council of Advisors
on Science and Technology, Report to the President, Forensic Science in Criminal Courts:
Ensuring Scientific Validity of Feature-Comparison Methods 60, 104–05 (2016), https://obamawhitehouse.archives.gov/sites/default/files/microsites/ostp/PCAST/pcast_forensic_science_report_final.pdf [https://perma.cc/3QWJ-2DG]).
[81] Abruquah, 483 Md.at 678–79 (citing United States v. Willock, 696 F. Supp. 2d 536, 572, 574 (D. Md. 2010); United States v. Taylor, 663 F. Supp. 2d 1170, 1180 (D.N.M. 2009); United States v. Glynn, 578 F. Supp. 2d 567, 574–75 (S.D.N.Y. 2008); Gardner v. United States, 140 A.3d 1172, 1183 (D.C. 2016); Commonwealth v. Pytou Heang, 942 N.E.2d 927, 938 (Mass. 2011)).
[82] Rochkind v. Stevenson, 471 Md. 1, 31, 38 (2020) (quoting Horn, 185 F. Supp. 2d at 553–55).
[83] Abruquah, 483 Md. at 679.
[84] Id. (alteration in original) (quoting Tr. Mot. Hg., United States v. Medley, No. PWG-17-242, 119 (D. Md. Apr. 24, 2018), ecf.mdd.uscourts.gov/doc1/09319506173).
[85] Id. (citing United States v. Adams, 444 F. Supp. 3d 1248, 1256, 1261, 1267 (D. Or. 2020); United States v. Shipp, 422 F. Supp. 3d 762, 783 (E.D.N.Y. 2019); Williams v. United States, 210 A.3d 734, 744 (D.C. 2019)).
[86] Id. at 696.
[87] Id.
[88] Id. at 699 (Hotten, J., dissenting).
[89] Abruquah, 483 Md. at 709.
[90] Id. at 710.
[91] Justice Angela M. Eaves began her judicial career in 2000 when she became an Associate Judge for the District Court of Maryland, District 9, Hartford County. Angela M. Eaves, Md. Manual On-Line (Dec. 3, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/msa13120.html. In 2007, Justice Eaves became an Associate Judge for the Hartford County Circuit Court. Id. From 2015 to 2022, Justice Eaves served as the Hartford County Circuit Court Administrative Judge. Id. With over two decades of experience, Justice Eaves was appointed to Court of Appeals on February 17, 2022. See Appointments by Governor, 1996–2004, Md. Manual On-Line (July 31, 2024), https://msa.maryland.gov/msa/mdmanual/29ap/html/apappoint.html.
[92] Abruquah, 483 Md. at 713 (Gould, J., dissenting).
[93] Oglesby v. Balt. Sch. Assocs., 484 Md. 296, 296 (2023).
[94] Id. at 302.
[95] Id. at 303.
[96] Id. at 304.
[97] Id. at 319.
[98] Id. at 319–23.
[99] Oglesby, 484 Md. at 324 (quoting Oglesby v. Balt. Sch. Assocs., No. CSA-REG-0130-2021, 2022 WL 3211044, at *8 (App. Ct. Md. Aug. 9, 2022)).
[100] Id. at 333–34.
[101] Id. at 334.
[102] Id. at 341.
[103] Id. at 343.
[104] Id. at 347.
[105] Oglesby, 484 Md. at 358.
[106] Id. at 357.
[107] Id.
[108] Id. at 358.
[109] Id. at 362.
[110] Katz, Abosch, Windesheim, Gershman & Freedman, P.A. v. Parkway Neuroscience & Spine Institute, LLC,485 Md. 335 (2023).
[111] Id. at 342–43.
[112] Id. at 343.
[113] Id. at 344.
[114] Id. at 342.
[115] Id. at 345.
[116] KatzAbosch, 485 Md.at 345.
[117] Id. at 350.
[118] Id. at 353.
[119] Id. at 381.
[120] Id. at 381.
[121] KatzAbosch, 485 Md. at 381.
[122] Id.
[123] Id.
[124] Id. at 382.
[125] Id. at 383.
[126] Id. at 384.
[127] KatzAbosch, 485 Md. at 407 (Gould, J., concurring in part and dissenting in part).
[128] Id. at 407–08.
[129] Id. at 411.
[130] Id. at 412 (Watts, J., dissenting).
[131] Derek Stikeleather, 2023 and the Summer of Daubert, Md. Appellate Blog (Sept. 7, 2023), https://mdappblog.com/2023/09/07/2023-and-the-summer-of-daubert/. The Justices have cited Mr. Stikeleather three time in two Daubert cases. See State v. Matthews, 479 Md. 278, 284 n.1 (2022) (citingDerek Stikeleather, It’s Official: Maryland Accepts Daubert as Controlling Law for Admitting Expert Testimony, Md. Appellate Blog (Aug. 31, 2020), https://mdappblog.com/2020/08/31/its-official-maryland-accepts-daubert-as-controlling-law-for-admitting-expert-testimony/ [perma.cc/A342-NSSL]), and Rochkind v. Stevenson, 471 Md. 1, 47 (Watts, J., dissenting) (citing Derek Stikeleather, The End of Frye-Reed, Md. Appellate Blog, (Oct. 5, 2017), https://mdappblog.com/2017/10/05/the-end-of-frye-reed/ [https://perma.cc/62YQ-K7BV], and Derek Stikeleather, Update: The End of Frye-Reed Draws Closer, Md. Appellate Blog (May 1, 2018), https://mdappblog.com/2018/05/01/update-the-end-of-frye-reed-draws-closer/ [https://perma.cc/YC5U-JQD2]).
[132] KatzAbosch, 485 Md. at 385 (Booth, J., concurring).
[133] Id. at 386.
[134] Id. at 387.
[135] Id. at 398 (quoting Zervos v. Verizon N.Y., Inc., 252 F.3d 163, 168 n.4 (2d Cir. 2001)).
[136] Id. at 399 (quoting Calderon v. Thompson, 523 U.S. 538, 567 (1998) (Souter, J. dissenting)).
[137] Id. at 399 (quoting Henry J. Friendly, Indiscretion About Discretion, 31 Emory L.J. 747, 784 (1982)).
[138] KatzAbosch, 485 Md. at 401 (citing David F. Herr & Morgan L. Holcomb, Opinion and Expert Testimony in Federal and State Courts, Am. L. Inst. Am. Bar Ass’n 629, 642 (2007); Michael J. Saks, et al., Annotated Reference Manual on Scientific Evidence Second 23 (West 2004)).
[139] Id. at 401.
[140] Id. at 402 (quoting Dodge v. Cotter Corp., 328 F.3d 1212, 1223 (10th Cir. 2003)).
[141] Id. at 403 (quoting Dodge, 328 F.3d at 1223).
[142] Id. (quoting Dodge, 328 F.3d at 1223).
[143] Id. (quoting C.W. ex rel. Wood v. Textron, Inc., 807 F.3d 827, 835 (7th Cir. 2015)).
[144] KatzAbosch, 485 Md. at 403 (citing C.W., 807 F.3d at 835).
[145] Id. at 404 (quoting United States v. Brown, 415 F.3d 1257, 1266 (11th Cir. 2005)).
[146] Katz, Abosch, Windesheim, Gershman & Freedman, P.A. v. Parkway Neuroscience & Spine Inst., LLC, 487 Md. 632, 634 (2024).
[147] Id. at 635.
[148] See discussion infra Section III.A.
[149] Young v. State, 234 Md. App. 720, 731 (2017).
[150] See discussion infra Section III.B.
[151] See discussion infra Section III.B.
[152] Williams v. State, 457 Md. 551, 562 (2018).
[153] Ocean City, Md., Chamber of Com., Inc. v. Barufaldi, 434 Md. 381, 391 (2013).
[154] Id.
[155] Id. at 391.
[156] Jackson v. State, 364 Md. 192, 208 (2001).
[157] Hart v. Miller, 65 Md. App. 620, 626 (1985).
[158] Md. Rule 5-702(3).
[159] Oglesby, 484 Md. at 343.
[160] Id. at 308 n.8.
[161] Md. Rule 5-702.
[162] Oglesby, 484 Md. at 341.
[163] Rochkind, 471 Md. at 35.
[164] KatzAbosch, 485 Md.at 381.
[165] Id.
[166] Id. at 382.
[167] Id. at 406–07 (Booth, J., concurring).
[168] KatzAbosch, 485 Md. at 401–02 (Booth, J., concurring) (quoting Lawes v. CSA Architects & Engineers, LLP, 963 F.3d 72, 90 (1st Cir. 2020)).
[169] Abruquah v. State, 483 Md. 637, 652 n.5 (2023) (quoting State v. Matthews, 479 Md. 278, 305 (2022)).
[170] Id.
[171] Id.
[172] Id. at 710 (Hotten, J., dissenting); Id. at 712–13 (Gould, J., dissenting).
[173] Md. Const. art. IV, § 18(a).
[174] Md. Code Ann., Cts. & Jud. Proc. § 12-203 (West).
[175] See Mahai v. State, 474 Md. 648, 675 (2021).
[176] 1937 Md. Laws Ch. 238 (codified at Md. Code Ann., Cts. & Jud. Proc. § 12-305(1) (West).
[177]Md. Code Ann., Cts. & Jud. Proc. § 12-203.
[178] Brynja M. Booth, Petitions for Certiorari—View From the Bench, in Paul M. Sandler, Andrew D. Levy & Steven M. Klepper, Appellate Practice for the Maryland Lawyer: State and Federal 321, 326 (6th ed. 2023).
[179] Forsyth v. City of Hammond, 166 U.S. 506, 512 (1897).
[180] Rochkind v. Stevenson, 471 Md. 1, 34 (2020) (quoting Motorola Inc. v. Murray, 147 A.3d 751, 756 (D.C. 2016)).
[181] Id.
[182] Kazadi v. State,467 Md. 1, 46 (2020).
[183] Twining v. State, 234 Md. 97, 100 (1964).
[184] Md. Rule 4-312(e)(1) (“If the judge conducts the examination, the judge may permit the parties to supplement the examination by further inquiry or may submit to the jurors additional questions proposed by the parties.”).
[185] Kazadi, 467 Md. at 42 (quoting Maryland State Bar Ass’n, Model Jury Selection Questions for Criminal & Civil Trials xv (2018)).
[186] Id. at 46.
[187] See, e.g., 18 U.S.C. § 922.
[188] See Abruquah v. State, 483 Md. 637, 678–79 (2023).
[189] Id. at 702 (Hotten, J., dissenting); id. at 753 (Gould, J., dissenting).
[190] Abruquah, 483 Md. at 679 (Hotten, J., dissenting). From 2009 to 2015, Judge Paul Grimm sat on the Advisory Committee for the Federal Rules of Civil Procedure and chaired the discovery subcommittee. Paul Grimm, Duke L. https://law.duke.edu/fac/grimm (last vistited Apr. 25, 2025). Judge Grimm also taught evidence at both law schools in Maryland and lectured on technology and evidence throughout the country before retiring to serve as Director of the Bolch Judicial Institute. Id.
[191] See Lloyd v. Niceta, 485 Md. 422, 440 (2023).
[192] Md. Const. art. IV, § 18(a).
[193] See Md. Code Ann., Cts. & Jud. Proc. § 13-301 (West 2025).
[194] See Pearson v. State, 437 Md. 350, 371 (2014) (Harrell, J., concurring); Curtin v. State, 393 Md. 593, 618 (2006) (Bell, C.J., dissenting).
[195] Md. Code Ann., Cts. & Jud. Proc. § 12-203 (“If the Supreme Court of Maryland finds that review . . . is desirable and in the public interest, the Supreme Court of Maryland shall require by writ of certiorari that the case be certified to it for review and determination.”). Md. Const. art. IV, § 18(a) (“The Supreme Court of Maryland . . . shall adopt rules and regulations concerning the practice and procedure in and the administration of . . . the [] courts of this State, which shall have the force of law until rescinded, changed or modified by the Supreme Court of Maryland or otherwise by law.”).
[196] Abruquah v. State, 483 Md. 637, 663–64 (2023).
[197] Id. at 679.
[198] Md. Rule 1-104(a)(2)(A); see Rules Order, Supreme Court of Maryland 9–10 (Apr. 21, 2023).
[199] Md. Rule 1-104(a)(2)(B). The exception is that an “unreported per curiam opinion may not be cited as persuasive authority.” Id.
[200] Md. Rule 1-104(b).
[201] Md. Code Ann., Cts. & Jud. Proc. § 12-203 (West 2025).
[202] Oglesby v. Balt. Sch. Assocs., 484 Md. 296, 333–34 (2023).
[203] Id. at 347.
[204] Abruquah v. State, 483 Md. 637, 697 (2023) (quoting State v. Jordan, 480 Md. 490, 505 (2022)).
[205] Id. (quoting Dionas v. State, 436 Md. 97, 108 (2013)).
[206] Id.
[207] Id.
[208] Miller v. Mathias, 428 Md. 419, 446 (2012).
[209] Katz, Abosch, Windesheim, Gershman & Freedman, P.A. v. Parkway Neuroscience & Spine Inst., LLC, 485 Md. 335, 384 n.18 (2023).
[210] Id.
[211] Id.
[212] Id.
[213] Id. at 382 n.16.
[214] Id.
[215] Supra note 45.
[216] Supra notes 29–31.
[217] Rochkind v. Stevenson, 471 Md. 1, 38 (2020) (quoting United States v. Horn, 185 F. Supp. 2d 530, 554–55 (D. Md. 2002)).
[218] Abruquah v. State, 483 Md. 637, 652 n.5 (2023) (quoting State v. Matthews, 479 Md. 278, 305 (2022)).
[219] Wilson-X v. Dep’t of Hum. Res., 403 Md. 667, 675 (2008) (quoting Pasteur v. Skevofilax, 396 Md. 405, 433 (2007)).
[220] Ocean City, Md., Chamber of Com., Inc. v. Barufaldi, 434 Md. 381, 391 (2013).
[221] See C.W. ex rel. Wood v. Textron, Inc., 807 F.3d 827, 835 (7th Cir. 2015) (interpreting Fed. R. Evid. 702).
[222] Barufaldi, 434 Md. at 391.
[223] Rochkind v. Stevenson, 471 Md. 1, 38 (2020) (quoting United States v. Horn, 185 F. Supp. 2d 530, 554–55 (D. Md. 2002)).
[224] Id. at 37.
[225] Williams v. State, 457 Md. 551, 562 (2018).
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