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Expert Witnesses: What You Need To Know

Expert Witnesses

The world has become a much more complicated place in the modern age, especially with regard to technology and areas of expertise. The days when a jury of your peers would have sufficient knowledge of all facets of your case are gone.

Even such things as cell phone towers, and how accurately any given cell phone’s location could be pinpointed, must be explained to a jury by someone in that field in order for a cell phone record to be a meaningful part of the evidence in a trial.

In addition, everyone – or almost everyone – carries a cell phone now. If cell phones are a given element of daily life, how many more things out there require expert explanation?

This is why trials rely more and more upon expert testimony or expert witness. An expert witness is not like an eye-witness or character witness, who has some connection to the trial or the case.

An expert witness’s only connection to the case is his or her in-depth knowledge in a field that touches on an aspect of the case. Either the prosecution or the defense may call an expert witness.

Expert Witnesses: Federal Rules of Evidence

Most state laws about expert testimony are the same as the federal laws, although some states are not.

  • *FRE 702 – A judge may admit expert testimony into evidence if it assists the jury or the judge to “understand the evidence or to determine a fact in issue”
  • *FRE 703 – A qualified expert may give testimony based on the findings of others, as long as those findings are similar in kind to those used by the expert’s peers. In other words, a medical doctor may give his or her opinion on the findings of another medical doctor, but may not give his or her opinion on the findings of an acupuncturist.
  • *FRE 704 – A qualified expert may also give his or her opinion on the factual issue at hand of the case. In other words: he or she may not only say whether they think John Doe could have been killed in the manner suggested by the prosecution, but whether they think John Doe was killed in this manner.

Daubert and Frye Standards

In the early 1990s, the role of expert witnesses was shaped by the Supreme Court in several landmark cases, which are now applied to every case using expert testimony.

These are known as the Daubert and Frye standards – named for the cases that established the standard. Under the Daubert standard, the judge acts as the gatekeeper for expert testimony.

He or she must determine whether the opinion the expert is giving is both relevant and reliable – much like the standards in place for admissible evidence. To determine whether an expert testimony is relevant and reliable, the judge has to apply 4 guidelines:

  1. Was the expert’s theory or technique tested, or can it be tested?
  2. Was the theory or technique subjected to peer review or publication?
  3. What is the error rate, or potential error rate of the theory or technique?
  4. Is there general acceptance of this theory or technique in the scientific community?

The Frye standard is not as rigorous, as it mainly encompasses this last guideline: general acceptance within the scientific community. Some states rely more on the Frye standard or a combination of both.

Judges are bound to remain impartial and focus on the validity of the methodology of the expert, not the conclusion. It’s the jury’s job to decide how important the testimony will be to the case through the process of the trial.

Take Away

Expert witnesses are necessary for today’s trials for many kinds of evidence. It is the job of a good defense attorney to choose the expert witnesses that will most help your case. If you are having issues related to the expert witness in your case, don’t hesitate to give us a call.

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This article was published on: May 31, 2017 and was last modified May 31, 2017
Posted in Criminal Law
Posted in Criminal Law