Raising the Bar: Rule 702 Changes Illuminate the Need for Science Literacy in the Judiciary

David Lee, MJLST Staffer

On December 1, 2023, amendments to Federal Rule of Evidence 702 (FRE 702) took effect.[1] FRE 702 governs the admissibility of expert witness testimony. Central to its purpose is ensuring that such testimony is both relevant to the case and based on a reliable foundation. The rule sets the qualifications for experts based on their knowledge, skill, experience, training, or education, and emphasizes the crucial role of the trial judge as a gatekeeper. This role involves assessing the testimony’s adherence to relevance and reliability before it reaches the jury, thereby upholding the fairness and integrity of the judicial process and ensuring that the legal system remains aligned with evolving scientific and technical knowledge.[2]

Prior to the amendments, there was inconsistent application of FRE 702.[3] According to the Advisory Committee on Evidence Rules, the changes serve to reinforce that the criteria for expert witness admissibility laid out in FRE 702 are just that – criteria for admissibility and not questions of weight.[4] When read properly, FRE 702 makes expert witness reliability a threshold question for judges to answer, and the amendments reinforce this “gatekeeping” function of judges.[5]  With the new amendments clarifying the role of judges as arbiters of whether an expert’s “opinion reflects a reliable application of the principles and methods [of relevant scientific, technical, or other specialized knowledge]” to the facts of the case, it is imperative that the judiciary is sufficiently literate in science and the scientific method to properly serve this function.

Rule 702. Testimony by Expert Witnesses (amendments italicized and stricken)

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if the proponent demonstrates to the court that it is more likely than not that:

(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert has reliably applied expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.

The Importance of Scientific Acumen on the Bench

Science literacy on the bench – referring to the judiciary’s understanding and comprehension of scientific principles and methodologies – has become increasingly vital in the modern legal landscape. This form of literacy encompasses not just a basic grasp of scientific concepts but also an appreciation of how scientific knowledge evolves and how it can be rigorously applied in legal contexts. As courts frequently encounter cases involving complex scientific evidence – from DNA analysis to digital forensics – judges equipped with science literacy are better positioned to evaluate the credibility and relevance of expert testimony accurately. The absence of this scientific acumen can lead to significant judicial errors or misunderstandings.[6] Entire branches of forensic science such as bite mark analysis, microscopic hair comparison, and tire track analysis – once taken for granted as valid and widely accepted by courts – have been discredited as unreliable and lacking scientific underpinnings.[7] These misjudgments about the validity of forensic methods have previously led to wrongful convictions.[8] Lack of understanding in environmental science has sometimes resulted in rulings on cases involving pollution and climate change that are highly controversial regarding their interpretation of the science.[9] These examples underline the necessity for judges to possess a robust foundation in scientific literacy to ensure just and informed decision-making in an era where science and technology are deeply intertwined with legal issues.

The Need for Additional Educational Initiatives

Judges are often apprehensive when confronted with complex scientific evidence in cases, partly due to their limited background in the hard sciences, as illustrated by one judge’s shift from pre-med to law after struggles with organic chemistry.[10] This apprehension underscores the growing necessity for science literacy in the judiciary, particularly given that judges are well-equipped to handle the fundamental aspects of scientific evidence: accuracy in observation and logical reasoning.[11] While judges may not be familiar with the specific terminologies and conventions of various scientific fields, their aptitude in swiftly grasping diverse issues, coupled with focused science education programs, would equip them to adeptly handle scientific matters in court. The approach for addressing the distinctive need for judicial education in science necessarily differs from the typical science education for scientists. Judges don’t require extensive training in theoretical concepts or complex statistical inferences as scientists do. Their role is more akin to a scientific journal editor, assessing if the scientific evidence presented meets acceptable standards. This task is supported by attorneys, who educate judges on pertinent scientific issues through briefs and arguments. The key for judicial science education is accessibility and breadth, given the variety of cases a judge encounters. The Reference Manual on Scientific Evidence, a crucial resource, helps judges understand scientific foundations and make informed decisions without instructing on the admissibility of specific evidence types; however, the most recent edition was published in 2011 and does not reflect advances in science or emerging technologies relevant to judges today.[12] Judicial education programs supported by the Federal Judicial Center further enhance judges’ capabilities in addressing complex scientific and technical information in our rapidly evolving world.[13] While these resources serve an important function, repeated misjudgments of the quality of scientific evidence by courts indicates that additional resources are needed.

The amendments to Federal Rule of Evidence 702 reemphasize the role that judges play regarding scientific and technical evidence. These changes not only clarify the gatekeeping role of judges in assessing expert witness testimony but also highlight the growing imperative for science literacy in the judiciary. This literacy is essential for judges to make informed, accurate decisions in an era increasingly dominated by complex scientific evidence. The evolving landscape of science and technology underscores the need for continuous educational initiatives to equip judges with the necessary tools to adapt and respond effectively. Resources like the Reference Manual on Scientific Evidence – despite needing updates – and educational programs provided by the Federal Judicial Center play a crucial role in this endeavor. As the legal world becomes more intertwined with scientific advancements, the judiciary’s ability to keep pace will be instrumental in upholding the integrity and efficacy of the justice system. This progression towards a more scientifically literate bench is not just a necessity but a responsibility.


[1] https://www.gand.uscourts.gov/news/federal-rules-amendments-effective-december-1-2023.

[2] https://www.law.cornell.edu/rules/fre/rule_702.

[3] https://www.jdsupra.com/legalnews/upcoming-fre-702-amendment-reemphasizes-6303408.

[4] Id.

[5] https://www.apslaw.com/its-your-business/2023/11/30/return-of-the-gatekeepers-amendments-to-rule-702-clarify-the-standard-of-admissibility-for-expert-witness-testimony.

[6] https://www.americanbar.org/groups/judicial/publications/appellate_issues/2019/winter/untested-forensic-sciences-present-trouble-in-the-courtroom.

[7] Id.

[8] Id.

[9] https://slate.com/news-and-politics/2023/12/supreme-court-vs-science.html.

[10] https://www.americanbar.org/groups/judicial/publications/judges_journal/2017/fall/science-educatifederal-judges.

[11] Id.

[12] https://www.nationalacademies.org/our-work/science-for-judges-development-of-the-reference-manual-on-scientific-evidence-4th-edition.

[13] Id.