critical literature review

C H A P T E R   1

Expert Testimony: Legal Principles C L A R E N C E WAT S O N

“[The Law of Evidence] constitutes a most important part of human opinion; it has fluctuated with the vicissitudes of society; it has advanced with its progress, and declined with its degradation. For it was when all the resources of superstition were exhausted, when the relics which were the most awful of all guarantees in a barbarous age, failed to ensure the veracity of a witness, that the judge in mere despair and conscious of his inability to discover the truth, called upon Providence to supply by a spe- cial interposition, the want of human judgment, and sagacity” (pp.  2–3).1 Through those words, Phillmore spoke to the necessary progress that had been made, even in his day, from an era of trials by ordeal and combat to the embrace of ancient Roman principles aimed at truth seeking amid conten- tious legal dispute.1 Ei incumbit probatio qui dicit, non qui negat—the burden of the proof lies upon him who affirms, not he who denies—is one such ancient Roman tenet and represents a core legal principle that roots contemporary laws of evidence.

The law of evidence in the United States, as it is recognized today, rep- resents a body of principles forged gradually over the centuries as citizens sought equitable resolution of legal disputes by the respective tribunals of their day. Infused with ancient Roman and medieval Norman ideals, English law was transported across the Atlantic along with the cultural customs of the British colonists in North America, and formed the foun- dation of the legal system in the United States.2 Surprisingly, although humankind ’s legal tradition can be traced back to ancient roots, the law of evidence, as we know it today, was essentially nonexistent until the 18th century and, as such, is in its infancy by comparison.3 Even at its beginnings, the focus of evidence law centered on the authentication of

C o p y r i g h t 2 0 1 4 . O x f o r d U n i v e r s i t y P r e s s .

A l l r i g h t s r e s e r v e d . M a y n o t b e r e p r o d u c e d i n a n y f o r m w i t h o u t p e r m i s s i o n f r o m t h e p u b l i s h e r , e x c e p t f a i r u s e s p e r m i t t e d u n d e r U . S . o r a p p l i c a b l e c o p y r i g h t l a w .

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documents or proof of writings, while issues regarding oral testimony of witnesses received little to no attention, except for barring testimony from individuals with interests in the matter’s outcome (including the disputing parties).3 Naturally, rules related to expert scientific testimony during trials were absent, allowing experts to testify with virtual free rein and with little distinction from lay witnesses, who were also permitted to offer opinion testimony.4

Over the course of centuries, it has been well recognized and accepted that courts need expert testimony to deal with matters that lie outside of the experience of the judge and jury. However, over that same timeframe, a growing and palpable tension developed in the courtroom regarding the proper balance of the necessity of expert testimony against its potentially prejudicial effects. As Judge Learned Hand wrote in 1901:  “No one will deny that the law should in some way effectively use expert knowledge wherever it will aid in settling disputes. The only question is as to how it can do so best” (p. 40).5 This chapter traces the historical roots of the legal principles and rules of admissibility governing expert witness testimony in the United States. With the seminal 1923 D.C. Circuit Court decision of Frye v. U.S.6 as our fulcrum point, we will explore the historical treatment of the expert witness and discuss contemporary legal principles regarding expert testimony.

E XPER T TE S TIMONY B EFORE FRYE

The historical record reflects the longstanding participation of experts assist- ing in legal disputes over the centuries, although the nature of that partici- pation has evolved over time. Prior to the more familiar practice of partisan experts in the courtroom, the use of expert knowledge by early British tribu- nals occurred in two forms: the special jury and expert advisors summoned by the court.7 Members of the special jury were expressly selected for their special knowledge or expertise, as they were considered especially qualified to decide the merits of particular legal claims. Depending on the case, these juries of experts ranged from panels of cooks and fishmongers to all-female juries determining claims of pregnancy.8 For example, in a 1351 case, a defen- dant, charged with selling rotten food, faced a jury of cooks and fishmongers, who decided the validity of the charges.7 The practice of impaneling a jury of matrons de ventre inspiciendo to render a verdict of whether a woman was “quick with child” has been traced back to at least the 13th century.8 Courts also summoned expert advisors to assist in cases where its knowledge was inadequate. For example, in a 1345 case involving an appeal of mayhem, a London court summoned surgeons to assist in determining whether a wound was fresh.5 While these practices involved the use of experts in deciding legal

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matters, the expert did not yet provide direct testimony to a jury for the pur- pose of assisting it to render a verdict.

In 1901, Judge Learned Hand recounted some of the earliest recorded cases where expert testimony was submitted to the jury for its delibera- tion: Alsop v. Bowtrell (1620), Rex v. Pembroke (1678), and the Spencer Cowper case (1699).5 In Alsop v.  Bowtrell, a jury, deciding the legitimacy of a child, heard testimony from physicians that it was possible for a woman to deliver a child 40 weeks and 9  days after her husband’s death. In the murder trial Rex v.  Pembroke, physicians testified on behalf of the prosecution and the defense regarding the victim’s cause of death and whether a man could die of wounds without fever. In the 1699 Spencer Cowper case, surgeons and sailors, who had been in sea fights, testified about whether the deceased had been drowned and whether a drowned body full of water would sink.

The use of expert testimony in this manner became more prevalent in the 18th century and thereafter, although the presence of evidentiary rules governing the admissibility of such testimony lagged significantly. In fact, there appeared to be only one legal criterion at that time for expert testi- mony: Individuals were qualified to speak as experts if they possessed spe- cial training or experience in the subject in question.4 Of course, such a broad standard only dealt with the issue of relevance and did nothing to address the validity or reliability of the expert’s testimony.

The English legal system’s Adversarial Revolution in the 18th century and its associated rise of the partisan expert in the courtroom impelled the development of rules governing expert evidence.4 Interestingly, prior to the 18th century, judges dominated criminal trials and lawyers were generally excluded from criminal proceedings. By the 1730s, judges began to assume a more neutral role and defense lawyers began to participate regularly in criminal trials, hence the Adversarial Revolution. As lawyers expanded their control over directing criminal defenses, two natural ramifications were the partisan selection of experts and explicit challenges to the admissibil- ity of evidence. From those evidentiary challenges sprang two major legal doctrines:  the hearsay doctrine and the opinion doctrine. These doctrines, for the first time, created a brighter boundary between the lay witness, who was no longer permitted to offer hearsay or opinion evidence, and the expert witness, who enjoyed a special exception to those rules.4

Lord Mansfield’s 1782 opinion in the civil case of Folkes v.  Chadd9 hard- ened the acceptance of partisan experts to assist the jury and heralded the need for rules of evidence governing expert testimony.10 In that case, plain- tiffs claimed that the erection of a bank to prevent flooding caused the decay of a nearby harbor. Plaintiffs presented to the jury testimony by “[p] ilots, mariners, and other seamen” and an engineer to support their claims.4 However, the trial judge excluded the testimony of the defendants’ expert on the basis that his explanations were essentially opinions and could not be

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used by the jury to reach a verdict. On appeal, Lord Mansfield, Chief Justice of the Royal Court of King’s Bench, found that the trial court erred in exclud- ing the defense expert’s testimony and held that opinion evidence by the defense expert was admissible. In clarifying the issue, Lord Mansfield rea- soned, “ . . . for in matters of science the reasonings of men of science can only be answered by men of science . . . In matters of science no other witnesses can be called . . . I cannot believe that where the question is, whether a defect arises from a natural or artificial cause, the opinions of men of science are not to be received. . . .”9

Lord Mansfield’s 1782 ruling appeared to be a resounding endorsement of expert testimony in the courtroom. However, as the use of expert witnesses became more commonplace during the 19th century, a swell of discontent with the practice could not be ignored, as U.S.  legal scholars lamented the “evils” of expert testimony.11 In 1909, Clearwater outlined some of those evils as follows: There are no satisfactory standards of expertness, and thus the testimony of charlatans is invited; the character of the evidence often given by so-called experts is partisan and unreliable; contradictory testi- mony of experts of apparently equal standing, having the same opportuni- ties for acquiring knowledge of the facts, has a confusing effect upon juries; unprincipled self-styled experts are sometimes unscrupulously hired to sup- port causes by specious and untruthful testimony; the litigant who has the longest purse can produce the most imposing array of experts; and the Bench sometimes permits the Bar to treat the accomplished and modest expert with studied contempt.12

In the early 20th century, there were widespread calls for reforma- tive action against unbridled expert testimony in the courtroom. A com- mon sentiment echoed throughout the legal system that unwary juries needed protection from misleading and corrupt expert testimony. Some U.S. jurisdictions responded by proposing or enacting legislation meant to leash expert testimony in American courts. In 1909, Michigan and Rhode Island had such legislation in place, while Maine was in the process of proposing similar laws.13 However, this reformative approach through legislation proved unsuccessful, as these laws were eventually considered unconstitutional. It became clear that any clarity regarding the admissi- bility of expert testimony would only come from the courts through case law. A hint of clarity came in 1923 with the federal circuit court decision in Frye v. United States.6

Fr ye v. U. S .

In August 1921, James Alphonso Frye was arrested and charged with rob- bery in Washington, DC. During a police interrogation, Frye confessed to the

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unsolved murder of a prominent Washington, DC, physician in November 1920. Frye was then indicted for premeditated murder; however, prior to his trial in July 1922, Frye recanted his confession.14 In an effort to determine the veracity of Frye’s false confession claims, Dr. William Marston examined Frye using a systolic blood pressure deception test. Dr.  Marston concluded that the test results indicated that Frye’s claims of innocence were truthful and, consequently, Frye’s defense proffered Dr. Marston’s testimony regard- ing his findings.

However, the trial judge excluded Dr.  Marston’s testimony as inadmis- sible, and Frye was convicted of second-degree murder after a four-day trial. Frye immediately appealed his conviction, arguing that the trial court erred by refusing to allow Dr.  Marston’s testimony. The appellate court affirmed the lower court’s decision and upheld Frye’s conviction. The court found that Dr.  Marston’s deception test had not yet gained sufficient scientific valida- tion to justify expert testimony regarding the test. The appellate court’s opinion set out the Frye “general acceptance” standard regarding the admis- sibility of scientific evidence as follows:

Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs (p. 1014).6

The Fr ye standard required judges to determine two issues prior to admitting scientific evidence:  (1)  To what field did the proffered scien- tific principle belong? (2) Was the scientific principle generally accepted in that particular field? A lthough the Fr ye standard represented a major shift in courts’ deliberations regarding scientific evidence, it was not without its critics. Criticisms of the Fr ye standard included concerns that many scientific principles did not fit neatly into a particular academic or professional field; that the threshold for “general acceptance” in a par- ticular field was unclear; and that it was not clear whether the underlying scientific principle or the application of the scientific principle required general acceptance.15

Moreover, questions arose about whether Fr ye’s “general acceptance” test would erroneously exclude novel but otherwise reliable scientific principles that were too new to gain general acceptance in its field.16 Despite these criticisms, the Fr ye test eventually became the gold stan- dard in federal and state courts for the admissibility of scientific expert testimony over the next 50  years. The lure of a seemingly definitive

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method of ensuring the reliability of scientific evidence in the courtroom seemed irresistible.

U. S . FEDER AL RULE S OF E VIDENCE OF 1975

While the Frye case appeared to provide much-needed clarity regarding the admissibility of scientific evidence, the body of evidence law as a whole remained in a state of disarray. Legal scholars proposing reformation of U.S.  evidence law pointed to frequent inconsistencies in its application.17 As Ladd argued, “A review of the history of evidence, with its spotted and often accidental growth, is persuasive proof of the need of introspective study of the law of evidence with a view to far-reaching improvement” (p. 218).18

In 1975, Congress responded by enacting the Federal Rules of Evidence, a codified set of rules that federal judges were required to apply in evidentiary matters. Despite Congress’s intent to provide clarity, the Rules inadvertently contributed to the long-chronicled quandary regarding the admissibility of expert testimony. Specifically, the 1975 Federal Rule of Evidence (FRE) 702 addressed admissible expert testimony as follows:

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 quali- fied as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of opinion or otherwise.19

Patently absent from the language of FRE 702 was the Frye “general acceptance” test. Furthermore, it was unclear whether the Frye standard had even been considered, since no such indication appeared in the Advisory Committee Notes to Congress or during Congressional floor debates regard- ing the proposed Rules.20 Naturally, the resulting uncertainty about whether Frye’s “general acceptance” standard survived the adoption of the Rules threw courts into a tailspin.

Most state courts and some federal courts continued to follow the “gen- eral acceptance” standard, reasoning that the Rules did not explicitly aban- don the established common law rule.21 Other courts viewed the “general acceptance” standard as inconsistent with and implicitly rejected by FRE 402, which stated that “[a] ll relevant evidence is admissible, except as other- wise provided by the Constitution of the United States, by Act of Congress, by these rules, or by other rules prescribed by the Supreme Court pursuant to statutory authority.”22 Since the Rules did not include criteria regarding general acceptance in a scientific field to establish relevance, those courts viewed Frye as being implicitly repealed by the Rules.

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The debate regarding the appropriate standard for admissibility of sci- entific evidence escalated throughout the 1980s and early 1990s. Growing concerns about “ junk science” or unreliable scientific testimony in the court- room fueled the debate.23 The perception that the law extended “equal dig- nity to the opinions of charlatans and Nobel Prize winners” with only lay juries to make the distinction was unsettling to legal scholars.24 Ultimately, the U.S. Supreme Court weighed in on the debate and clarified the status of the Frye “general acceptance” standard in the face of FRE 702 with its 1993 ruling in Daubert v. Merrell Dow Pharmaceuticals.25

D auber t v. Mer rell D o w Phar mac eutic als

In 1993, the U.S. Supreme Court answered the question debated by the legal community since the Federal Rules of Evidence were enacted in 1975:  Did the Frye “general acceptance” standard survive FRE 702? The Court’s answer was outlined in its opinion in Daubert v.  Merrell Dow Pharmaceuticals.25 In Daubert, two child plaintiffs sued Merrell Dow, alleg- ing that their mothers’ ingestion during pregnancy of Merrell Dow’s anti- emetic product, Bendectin, caused their birth defects. The district court granted Merrell Dow’s motion for summary judgment upon consideration of an affidavit by defendant’s expert that epidemiological studies had not established a statistically significant association between birth defects and Bendectin. The district court rejected plaintiffs’ expert testimony that test tube and animal studies demonstrated a link between the drug and birth defects because, in the court’s view, that evidence was not generally accepted in its field. The Ninth Circuit Court of Appeals affirmed the dis- trict court’s decision.

On certiorari, the U.S. Supreme Court vacated the lower court’s deci- sion, holding that the Federal Rules of Evidence superseded Frye’s “general acceptance” test. The Court’s opinion designated the judge—not the scien- tific community—as the gatekeeper in determining whether relevant sci- entific evidence met the reliability threshold necessary to be admissible. To assist judges with this determination, the court offered nonexclusive factors that may be considered when deciding the admissibility of scientific evi- dence: (1) whether the theory or technique in question can be and has been tested, (2) whether the theory or technique has been subject to peer review and publication, (3) whether the theory or technique has a known or poten- tial rate of error, (4)  whether standards exist for control of the theory’s or technique’s operation, and (5) whether the theory or technique has attracted widespread acceptance within a relevant scientific community. Interestingly, the Court included acceptance in the relevant scientific community as a factor to consider, despite setting aside the Frye test. In the Court’s view, a

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scientific community’s “general acceptance” is only one of many factors that should be considered in admissibility determinations.

While Daubert clarified the status of the Frye standard, it left open other issues regarding the admissibility of expert testimony, which were later addressed by the Court. In General Electric Co. v. Joiner,26 the Supreme Court reaffirmed the judge’s gatekeeper role and ruled that the appropri- ate review standard for a judge’s decision to exclude expert evidence is the abuse of discretion standard. The Joiner decision also highlighted the gate- keeper’s authority to scrutinize the connectivity between an expert’s prof- fered opinion and the data used to support that opinion. In Kumho Tire Co., Ltd. v. Carmichael,27 the Supreme Court addressed the issue of whether the Daubert ruling only applied to expert testimony based on scientific prin- ciples rather than testimony based on skill and experience-based knowl- edge. The Court held that Daubert criteria were to be applied by the judges in a flexible and nonexhaustive manner to ensure the reliability of not only scientific principle-based evidence, but all relevant expert evidence. Accordingly, testimony in nonlaboratory-based sciences, or “soft sciences,” such as psychology, sociology, and economics, appropriately fall within the judge’s gatekeeper scrutiny, as outlined in Daubert, to ensure its reliability in the courtroom.

While Daubert and its progeny resolved critical issues regarding admis- sibility standards for expert testimony in federal courts, not all state juris- dictions follow the federal rules or the Daubert decision. In fact, while some states have embraced the Daubert ruling, other state jurisdictions have explicitly rejected Daubert in favor of the Frye standard.28 As a result, the Frye test remains the prevailing standard in some states, and expert testimony in those jurisdictions must satisfy the “general acceptance” requirement before being presented to a jury. Therefore, it is important for testifying experts to be aware of the jurisdiction’s applicable admissibility standard by which their testimony will be measured and challenged. The purpose of these stan- dards is to ensure that an expert’s opinions are sound and reliable, and not mere speculation.

E XPER T S IN THE CO UR TRO OM

Long before the applicable admissibility standard issue is raised in the courtroom, attorneys wrestling with the decision to proffer scientific tes- timony must consider a crucial question: Will expert testimony be helpful to the fact finder in deciding a particular case? This question reflects the requirement that expert testimony must assist the judge or jury in decid- ing a factual issue that falls outside of ordinary knowledge or experience. Of course, to be helpful to the jury, the content of the expert’s proffered

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testimony must be relevant to some issue in the case. Expert testimony deemed irrelevant, and therefore unhelpful, will be excluded as a matter of law.

A judge may also exclude expert testimony on matters commonly known or experienced by the average layperson, since that testimony can be consid- ered unhelpful and potentially prejudicial. The exclusion of such testimony can be justified by concerns that experts are able to “assume a posture of mystic infallibility in the eyes of a jury of laymen” and could unduly influ- ence or mislead jurors on issues that they are already equipped to consider.29 There are times, however, where experts may be permitted to testify about matters within the average layperson’s knowledge or experience. In situa- tions where an expert’s professional training or experience can provide a more in-depth understanding of matters commonly known or experienced by average jurors, such testimony may be considered helpful and properly admitted to a jury.

While expert testimony must be helpful and assist the fact finder, it can- not overreach into the province of the jury with opinions regarding witness credibility or determinations of the criminal or civil liability of involved par- ties.30 The job of the testifying expert is to offer specialized knowledge where it is needed in order to assist the jury in effectively performing its exclusive function:  reaching just verdicts based on the evidence. It is the role of the expert to educate the jury, not replace it. It is role of the jury to weigh witness credibility and decide the ultimate issue—the verdict. Courts will generally allow experts to offer opinions that embrace the ultimate issue, while juries are empowered to assign weight to such opinions against all of the evidence presented in a case.

To be helpful to the fact finder, an expert must be qualified to discuss the subject about which the expert testimony is being offered. The reasoning for this rule is plain: The purpose of expert testimony is to assist the jury in drawing its inferences regarding factual issues more reliably than it would unaided. Expert testimony by individuals who are not qualified in the subject matter to which they are testifying cannot fulfill this purpose. Accordingly, the trial judge must determine whether a proffered expert possesses the req- uisite specialized knowledge regarding particular factual issues that jurors will consider in reaching a verdict.

The presence or absence of academic credentials does not necessarily determine whether a witness will qualify as an expert. In some situations, experience alone may suffice, as long as the expert’s experience affords a degree of expertise analogous to that of formally educated experts. The type of qualifications required by a court will depend on the nature of the opin- ions being offered by the expert. Hence, an expert’s qualifications may be based on formal or informal education, experience, or a combination of these factors, depending on the proffered testimony. A judicial determination of a

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proffered expert’s knowledge, training, experience, and education will take place in light of the specific opinion in question.

In fields such as medicine, which have become increasingly technical and specialized, experts must take special care only to offer opinions within their scope of expertise; otherwise, they run the risk of having their testimony excluded. For example, it is well accepted that being a physician alone does not qualify one to offer an opinion in every type of medical malpractice case. Similarly, not every mental health professional will necessarily be qualified as an expert to testify to every mental health question presented in court.

Even when an expert is qualified to offer testimony that is relevant to a legal matter, a judge has the discretion to exclude such testimony, if its prejudicial effect outweighs its probative value. Expert testimony that is rel- evant but nonetheless likely to mislead or confuse the jury may be barred as unduly prejudicial. For example, an appellate court upheld a district court’s decision to exclude a psychologist’s testimony regarding the reliability of eyewitness identifications on the basis that the testimony would likely con- fuse or mislead the jury.31 In that case, the defendant attempted to appeal his robbery convictions, alleging that the district court erred in excluding his expert’s testimony about factors that have an adverse impact on eyewitness identifications.

Given the potential pitfalls that experts may face when offering opinions in the courtroom, it is important for the expert to be aware of admissibility requirements in the relevant jurisdiction. Consultation with the retaining attorney to ensure that the expert’s report and opinion satisfy the applicable admissibility standard is a prudent step. Experts should refrain from offer- ing opinions that lie outside of their scope of expertise in order to preserve their role as a reliable educator in the courtroom.

RE A SONAB LE MED IC AL CER TAINT Y

When psychiatrists and other physicians provide expert opinions to the court through reports or testimony, they are often asked by attorneys to state their opinions with “reasonable medical certainty” or “reasonable medical probability.” Similarly, nonphysician experts may be asked to state their opinions with “reasonable scientific certainty.” While these phrases have become part of the standard lexicon in cases where medical or scientific expert testimony is introduced, there has been confusion among attorneys, judges, and experts about the precise meaning of those phrases.32,33

Moreover, the obscure and mysterious origin of these phrases has been noted in the legal literature, adding to the haze surrounding their use.34 Lewin traces the genesis of “reasonable medical certainty” to the early 20th century and the Illinois Bar’s attempt to reconcile the troublesome

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application of two evidentiary rules adopted by the Illinois Supreme Court: the “reasonable-certainty rule” and the “ultimate-issue rule.”33 The reason- able-certainty rule excluded testimony about future damages that were not reasonably certain to be incurred; the ultimate-issue rule prohibited expert witnesses from expressing definitive opinions regarding ultimate issues reserved for the jury, such as causation. Accordingly, medical experts in personal injury matters were required to testify with reasonable certainty about future damages but were banned from giving definitive opinions concerning causation. Lewin33 argued that plaintiffs’ attorneys, seeking to avoid the tripwire set by these rules, devised the “reasonable medical cer- tainty” language to elicit favorable expert testimony safely. Between the 1930s and 1960s, the phrase “reasonable medical certainty” became firmly embedded within legal parlance nationwide.

Regardless of its origin, the precise meaning of “reasonable medical cer- tainty” eluded the very experts from whom those words were expected to emanate. Rappeport32 pointed out that some physicians believed that the phrase was equivalent to “beyond a reasonable doubt,” while others viewed it as meaning a “preponderance of the evidence.” Diamond argued that the phrase should represent “the psychiatrist’s highest level of confidence in the validity and reliability of his opinion,” which is based on clinical judgment and is not translatable into the legal standards of proof used by juries during deliberations.35

As it currently stands, “reasonable medical certainty” means that a physi- cian believes his or her opinion to be “more likely than not” true or accurate. The phrase communicates to jurors the degree of clinical confidence that an expert assigns to an opinion, which was reached by the application of spe- cialized knowledge to the facts of the case. It is usually insufficient to couch expert opinion in terms of “possibility.” Failure to express opinions with the requisite level of certainty or probability (depending on the jurisdiction’s preference) may be detrimental to the case of the expert’s retaining attor- ney. Accordingly, the prudent expert should be aware of the level of certainty required by the jurisdiction in which he or she is testifying. Before offering an opinion in an unfamiliar jurisdiction, the expert is advised to consult with the retaining attorney regarding any nuanced but mandatory jurisdictional language, such as “reasonable medical probability,” “reasonable psychiatric certainty,” or any other variant.

CONCLUSION

The role of the expert witness is to educate the court on matters that lie beyond the sphere of the average fact finder’s experience or knowledge. It is the expert’s specialized knowledge, skill, experience, and training that

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unlock the gateway to the courtroom. Notably, the relevance and reliability of an expert’s opinion are the sine qua non of admission into trial proceedings. Whether a particular jurisdiction adheres to Daubert or Frye admissibility standards, it behooves the proffered expert to provide opinions that con- form to the applicable standard in order to survive the scrutiny of the judi- cial gatekeeper. To the extent possible, expert opinions should be expressed to the degree of certainty required by the jurisdiction where the opinion is to be offered.

REFERENCE S

1. Phillmore JG. The History and Principles of the Law of Evidence: As Illustrating Our Social Progress. London: Benning & Co; 1850.

2. Pacia R A, Pacia R A. Roman contributions to American civil jurisprudence. Rhode Island Bar Journal. 2001; 49: 5.

3. Langbein JH. Historical foundations of the law of evidence: a view from the Ryder Sources. Columbia Law Review. 1996; 96: 1168–1202.

4. Golan T. Revisiting the history of scientific expert testimony. Brooklyn Law Review. 2008; 73(3): 879–942.

5. Hand L. Historical and practical considerations regarding expert testimony. Harvard Law Review. 1901; 15(1): 40–58.

6. Frye v. U.S., 293 F. 1013 (D.C. Cir 1923). 7. Mnookin JL. Idealizing science and demonizing experts: an intellectual his-

tory of expert evidence. Villanova Law Review. 2007; 52(4): 763–802. 8. Oldham JC. The origins of the special jury. University of Chicago Law Review.

1983; 50(1): 137–221. 9. Folkes v. Chadd, 99 Eng. Rep. 589 (1782). 10. Landsman S. One hundred years of rectitude: medical witnesses at the Old

Bailey, 1717–1817. Law and History Review. 1998; 16(3): 445–494. 11. Friedman LM. Expert testimony, its abuse and reformation. Yale Law Journal.

1910; 19(4): 247–257. 12. Clearwater AT. Medical expert testimony. The North American Review. 1909;

189(643): 821–830. 13. New York State Bar Association. Proceedings of the Thirty-Second Annual Meeting

of the New York State Bar. Albany: The Argus Company; 1909. 14. Golan T. Laws of Men and Laws of Nature: The History of Scientific Expert

Testimony in England and America. Cambridge, MA: Harvard University Press; 2004.

15. Horton TM. The debate is over: Frye lives no more. Thurgood Marshall Law Review. 1994; 19(2): 379–400.

16. Dillhoff M. Science, law, and truth: defining the scope of the Daubert trilogy. Notre Dame Law Review. 2011; 86(3): 1289–1318.

17. Morgan EM. Practical difficulties impeding reform in the law of evidence. Vanderbilt Law Review. 1961; 14(3): 725–740.

18. Ladd M. A modern code of evidence. Iowa Law Review. 1942; 27(2): 213–231. 19. Fed. R. Evid. 702 (1975).

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