The Forensic Expert and Court Testimony

The U.S. Supreme Court, in Melendez-Diaz v. Massachusetts, found that forensic laboratories may be cross-examined by defendants in criminal cases.  This means that these professionals must be educated in the criminal and civil courts and be prepared to provide their testimony when necessary.

Forensic experts, who may be employed by academic institutions or through local, state or federal laboratories, are often called upon to serve as expert witnesses or consultants regarding scientific and technical issues. They may be subpoenaed or appointed by the court in a criminal or civil case, and they often provide third-party opinions on information submitted by prosecution and defense experts.

Because of the important role they play in the criminal justice system, they must be able to expertly follow lab protocol and procedures and obtain the facts and information on which to base their conclusions.

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Forensic experts must also be able to prepare written reports, which reflect the use of scientific method, and include valid documentation. Further, they must be able to guide their clients on the proper technical and legal terms and procedures.

Forensic experts are particularly important during the pretrial discovery process, as they work with attorneys to gather information that may help them prove their case. This process is often driven by strict deadlines imposed by the court, which means that their work must be swift and highly focused.

During a trial, forensic experts must convince a judge or jury that they are expert witnesses and that their testimony is clear, concise, and truthful. As such, they must:

  • Be able to reference evidence and provide reports of testing or retesting
  • Be knowledgeable about state and local laws and about the Federal Rules of Evidence
  • Remain credible by answering questions in an intelligent manner, while also recognizing the unauthorized appearance of evidence
  • Be knowledgeable about the ethical standards of conduct and always display objectivity
  • Remain calm and in control during questioning, even during difficult cross-examination