The Federal Rules of Evidence acknowledges two types of witnesses; the first is the lay witness and the second is expert witnesses. The lay witness has “personal knowledge of the underlying facts of the case” (http://abanet.org/litigation/tips/gatekeepersarticle.html). “They testify to perceptions, facts, and data, grounded in their own experience” (Nemeth, 2001). Lay witnesses prohibited from testifying to their opinions. An example of a lay witness would be a person who watched his friend stab another man.
The second type of witness is the expert witness. An expert witness has “special knowledge or skill gained by education, training, or experience” (http://lectlaw.com/files/exp27.htm). Basically, expert witnesses have more knowledge, training, or experience than ordinary citizens. Some of the common expert witnesses that testify in criminal proceeding are professionals in the medical, mental, or forensic fields. As mentioned above, the lay witness is not allowed to testify about his or her opinions. Yet, “expert witnesses attend court to interpret and express their opinions about the facts” (http://lectlaw.com/files/exp27.htm).
Rule 702 of the FRE states, “If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education may testify thereto in the form of an opinion…” (www.law.cornell.edu/rules/fre/rules.htm#701). “Courts expect such commentary (opinion)” (Nemeth, 2001). The judge has wide discretion on what it “scientific” (i.e. plant DNA).The Daubert v. Merrell-Dow Pharmaceuticals, Inc., 509 U.S. (1993) case established that it is his or her (judge) responsibility to “ensure that any and all scientific, technical, and specialized testimony admitted into evidence is not on relevant but reliable” (abanet.org/litigation/tips/gatekeepersarticle.html).
Once the judge has decided that the testimony is accepted in the scientific community and the expert swears in, he or she will testify to his or her opinions about the case. Experts are even allowed to form opinions and testify about them to evidence that was not admissible. Rule 703 of FRE states, “Facts or data does not need to be admissible in evidence in order for an opinion or inference to be admitted” (www.law.cornell.edu/rules/fre/rules.htm#701).
An expert witness must make a declaration of their expertise in order to testify. Declarations can be made in two ways, (1) an oral examination, and (2) a curriculum vitae. A curriculum vitae is in all other words a type of résumé. Some of the information should include academic training, certificates and licenses, and employment experience. The expert makes his or her declaration after swearing in and before testifying (http://lectlaw.com/files/exp27.htm).
I believe that expert witnesses carry so much weight because they “are perceived as scientific and dispassionate” (Nemeth, 2001). Therefore, they are seen as having no reason to lie. Because they do make opinions, although they are based on the facts, another expert witness will usually be called to “debunk” the opinion of the first expert. Therefore, there is usually a battle of experts.
Heather Zarka
Reference List:
Atlas, N.F., & Atlas, S.J., 2001. Finding, Preparing, and Defending an Expert in the Age of Judicial Gatekeepers. Retrieved September 14, 2006 from American Bar Association at http://abanet.org/litigation/tips/gatekeepersarticle.html
Nemeth, C.P., 2001. Law & Evidence: A Primer for Criminal Justice, Criminology, Law, and Legal Studies. Prentice-Hall, Inc., Upper Saddle River, New Jersey 07458.
Daley, T.T., 1996. Guidelines for the Expert Witness. Retrieved September 14, 2006 from http://lectlaw.com/files/exp27.htm
Cornell Law, 2006. Retrieved September 14, 2006 from http://www.law.cornell.edu/rules/fre/rules.htm#701
