Jurisprudence

“Forensic” is defined by Black’s Law Dictionary as “belonging to courts of justice.”  Forensic science is “the application of scientific knowledge to legal problems” (Merriam-Webster Dictionary) such as criminal trials, civil disputes, and arbitration proceedings to assist courts in resolving questions of fact.  Many of the forensic sciences – such as fingerprint analysis and document examination – originally developed from the need for lawyers to explain the significance of physical evidence to a case, often to identify a perpetrator of a crime.  All forensic science is evidence used by lawyers in presenting and explaining their cases in court.

Rapid advances in scientific knowledge during the last century resulted in scrutiny by attorneys and courts of the validity of then-current scientific analytical techniques.  Consequently, many areas of forensic science—defined by the laws of evidence as “technical or other specialized knowledge” — are being evaluated by courts under changing standards of reliability, validity, and admissibility.  A forensic scientist will frequently be asked to provide testimony as an expert witness who has conducted a scientific analysis of the evidence in a legal proceeding.  Consequently, forensic scientists must be aware of the process involved in being qualified as an expert and the evidence standards that will be applied to the scientific analysis performed by the forensic scientist.  Expertise comes from education, training, or experience and can be based on the scientific method or on specialized training.

Scope of Work

Counsel on both sides of a matter being tried in court, as well as the judge presiding over the trial, are lawyers.  They are the main players in the drama of the courtroom.  A lawyer who uses expert testimony in a criminal, civil, or other legal proceeding must know the laws that govern the admissibility of scientific evidence and be able to apply these laws when submitting or challenging scientific evidence in depositions and court proceedings.  The judge, also, must understand the issues concerning the validity and admissibility of scientific evidence and must ensure the legality of the entire process.  Much depends on the knowledge, training, education, and experience of the forensic scientist whom a lawyer seeks to qualify as an expert witness since an expert witness, and only an expert witness, is permitted to testify to an opinion based on analyses performed by the expert.


Courtroom testimony of an expert witness 
explaining findings in a case.

Although each deposition, hearing, or court appearance is a unique experience, forensic scientists testifying in a legal proceeding may reasonably expect questioning to cover at least a few key areas before the scientist is qualified as an expert by the judge.  Either lawyer may ask about the field of specialization in which the witness claims to be an expert, the reliability of analyses based on that specialty, and the witness’s qualifications in that specialized field.  Education in the field of specialized knowledge in which the witness claims to be proficient will be most relevant and may cover any and all formal education the witness has — or has not — completed.  Any publications or educational materials written or edited by the witness or by others in the field may be used to either support or challenge the witness’s qualifications, opinions, and conclusions.  Professional or technical training in the specialty, the witness’s performance during that training, as well as certifications or other credentials related to the specialty, may also be addressed.

The expert’s experience in the field of specialized knowledge may be covered, together with any issues related to the expert’s performance in the field.  The witness’s performance at work — including written and oral performance evaluations, disciplinary proceedings, and any other evidence relevant to competence — may be scrutinized.  Testimony by the witness in prior proceedings may be used to support or undermine the reliability or validity of the expert’s opinion in the current matter.

After the forensic scientist has been accepted as an expert either by agreement of the parties or by the judge, direct examination by the lawyer retaining the expert is intended to allow the expert to favorably state the expert’s education, training, and experience in the field of specialized knowledge; the facts  relied upon when preparing reports, summaries, or opinions for the case; the theories, techniques, methods, or procedures applied by the expert to analyze the facts; and any conclusions or opinions the expert reached as a result of this process.  Direct examination is typically a smooth, comfortable exposition of the witness’s qualifications, reasoning, and opinion.

Cross-examination by opposing counsel is typically more challenging.  A primary goal of an expert witness’s cross-examination is to identify any weaknesses that may undermine the relevance, reliability, and/or validity of the expert’s conclusions.  Although the witness has already been accepted as an expert, cross-examining counsel may try to discredit the expert’s testimony and opinions before the “trier of fact,” usually the jury, by questioning the expert’s qualifications; knowledge of the scope, limits, validity, and reliability of the witness’s area of specialization; application of that specialized knowledge to the facts of the case; and/or relevance of the evidence to the issues in the case.  There are limits to all scientific disciplines.  Experts well-versed in their discipline should be aware of those limits and be able to testify with ease about what can – and cannot – be known regarding a given piece of evidence.

Education and Training

Members of the Jurisprudence Section must possess a law degree, have passed a bar examination, and be licensed members in good standing of the bar in one or more states.  Full-time law school students are eligible to join the section as student affiliates.  Continuing education is essential for lawyers to stay current as forensic science advances and legal standards adapt to these advances.  Judges are lawyers who have been appointed or elected to the bench.  Since judges serve as “gate-keepers” for the admissibility of scientific evidence and of expert witnesses, they too, should take continuing education courses to remain fully aware of the issues surrounding the admissibility, reliability, and validity of scientific evidence and of the experts testifying to its use.
The Jurisprudence Section works to provide this knowledge to scientist and lawyer alike through workshops and presentations during the AAFS Annual Scientific Meetings held in February.

Career Opportunities

Lawyers working with forensic science issues may be employed in a variety of broad fields or specialties and by a broad range of employers and organizations.  Some are in private practice; others work in District Attorney’s offices, State Attorney’s offices, Public Defender’s offices, or for federal, state, or local government agencies.  Some are employed by large private companies; still others teach in colleges and universities.  Hours of work and income are dependent on geographical area; place of employment; experience; status and reputation; and, type of practice.

©2021 American Academy of Forensic Sciences