Expert Witnesses and Scientific Evidence

Expert witnesses have a professional, ethical and legal obligations to ensure that their evidence in court adheres to the scientific method i.e. is reliable and accurate. Experts, however, face a myriad of legal challenges with regard to their role in the courtroom including perilous liability climate. The Fryer test has restricted the kind of scientific evidence that parties could present in court, thus, limiting both innovations and junk science.

Expert Witnesses and Scientific Evidence

In the modern courtroom, the role of expert witnesses continues to grow. Expert testifiers are called to help clarify most of the issues that pertain to particular scientific expertise ranging from fingerprints to bite marks. The pursuit of justice can only be enhanced when experts give sound and unbiased evidence at a trial. In most cases, courts presume that these witnesses are good in their area of specialization and rarely impeach them on the basis of their testimony. Moreover, most of the jurors rarely interrogate expert witnesses. This essay seeks to analyze legal challenges that expert witnesses face and the impact of the Frye test on the kind of evidence proffered during judicial proceedings.


Legal Issues that Expert Witnesses Face

At the contemporary trial, a judge has complete discretion on what kind of evidence, and expert witnesses to allow in his/her court. Thus, regardless of how pivotal evidence is to the party that presents it, either prosecution or defense, plaintiff or defendant, the judge is within his/her rights not to allow the evidence. Neubauer & Fradella explain that rendering to Daubert v Merrell the judge has discretion to determine whether to admit the expert’s testimony. The expert judge does this according to a four-prong method: testability of the expert witnesses’ method, subjection of the theory to peer review, the apparent or potential era of method, and lastly, whether the method/theory is generally accepted in scientific community. Consequently, expert testifiers face legal impediment of having a judge, who is usually not a scientist, try to determine veracity or lack of their evidence.  

The second aspect is the challenge that the scholarly evidence presented in court has to be admitted by the jury. One of the chief characteristics of the American judicial policy is that a "jury’s one peer" tries a person at trial. The problem, however, is that, like judges, the jury is not traded in the scientific method. In most of the fields, there is a certain prescribed procedure that determines how a researcher achieves his/her results. In experts’ testimony, witnesses present only brief explanations of their evidence while the jurors decide on its validity in a matter of days or even hours. Notwithstanding, the method and the outcome might take significantly more time to be conducted and developed. It is, thus, possible that, just like the judge, the jury will dismiss evidence, which is otherwise reliable or allow the one that is irrelevant based on their perceived credibility and honesty of the expert. 

 Parties rarely sanction the expert witnesses judicially. Most of the states have laws that protect anyone who appears in the court against future suits as a consequence of their testimony bar in case of perjury. However, according to Johnston and Sartwelle, when the expert testifier’s performance is neglectful, a client can sue the expert witness for any losses the former might accrue as a direct result of negligence. The case of Spaulding v Hussain is a practical example of this situation. Particularly, the court determined that a doctor who treated a patient had a reasonable duty to assist in the litigation. 

Another legal challenge that expert witnesses meet is the nature of their expected role in judicature. Usually, such a testifier is hired by one of the parties for the dispute to help prosecution or defense prove a certain aspect in the case. It is quite a common practice that two parties might hire two experts in the same area of expertise who present different ways of interpreting of the same issues. The jury has to decide which of the accounts from the experts look more viable. However, the fact that two testifiers can propose divergent explanation of the same idea raises questions about its scholarly and ultimately legal veracity. Courts try to find the objective truth. Nevertheless, they may encounter obstructions due to conflicting accounts in a scientific issue, which is supposed to be both foolproof and impartial. 

Lastly, the expert witnesses face the challenge in regard to the degree of trust, which the courts can develop concerning their testimony. For instance, for many years, forensic fingerprint evidence experts would treat it as virtually a hundred percent free of errors. According to Mnookin, subsequently, the appearance of fingerprint evidence would usually lead to conviction of the defendant. However, the former evidence can have inaccuracies, as it is apparent from the case of Brandon Mayfield whom the FBI had wrongly accused of being a terrorist before the police caught a person with similar prints. Thus, one has to dispute how many people were sentenced by mistake due to the evidence that the experts provided the jury with as virtually error-free one but which was not. 

Impact that the Frye Test Has on Scientific Evidence Proffered at Trial

The Fryer test increased the role of the judge in determination of the expert evidence offered at trial. Now the judge decides what kind of scientific evidence appears in court. Moreover, during the trial, the decision of the judge concerning allowing this evidence is not challengeable unless there is a manifest wrongdoing.

The test also restricted the ability of parties in the case to rely on the up-to-date evidence based on new technologies. The court unequivocally noted that it would not admit evidence of scientific principle that was “experimental” rather than “demonstrable”. The reason is that in order to use any evidence the parties have to demonstrate that the evidence would be found acceptable by researchers of the particular area of studies.

However, while the Frye test controlled the availability of testimony that one could describe as new and innovative, the amount of junk science in the courtroom was also reduced. Without the court defining allowable boundaries in regard to science, the judicatory would have to deal with pseudo-science, which would not only waste valuable legal time but miscarry justice. In a bid to win their cases, many parties would present expert witnesses in the fields that are either non-existent or as the court notes,  are purely experimental and not verifiable by other researchers in the same area of study. 


In conclusion, the essay sought to explore the legal challenges that expert witnesses face as well as the effect of the Fryer decision on the type of scientific evidence offered in court. Expert testifiers rely on the discretion of the judge to present theoretical evidence. Secondly, jurors are not usually trained in the field of science. Thirdly, the question of objective truth arises as experts are hired by one party to prove an aspect of the case while in essence they are supposed to take an impartial view. The Fryer test increased the role of judging the admission of scientific evidence. It also dealt with the new innovative researches since the courts avoided “experimental” rather than “demonstrable” science. However, the positive feature is that it reduced instances of junk science in judicature. 

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