Expert Witnesses

Some of the most recently released questions from the NCBE deal with expert witnesses. Specifically, the focus of these questions is on when (and when not) expert testimony should be admissible. It's an important inquiry since experts can use their knowledge or skill to draw conclusions while non-experts can only base their opinions on information personally observed. 

In a very general sense, whether expert testimony is proper depends entirely on whether admitting that testimony will assist the jury. Stated otherwise, if the expert testimony will not assist the jury, then it should probably be excluded.

But that's a bit too general. The Federal Rules provide 4 elements, all of which must be satisfied, for expert testimony to be allowable.  Each of them plays off of the policy stated above: if any of the 4 is lacking, then the testimony is far less likely to assist the jury. 

A witness who is qualified as an expert (whether by knowledge, skill, experience, training, or education) may testify in the form of an opinion or otherwise if all of the following are satisfied:

~ the expert's scientific, technical or other specialized knowledge will help the jury to understand the evidence or to determine a fact in issue.

~ the testimony is based on sufficient facts or data

~ the testimony is the product of reliable principles and methods

~ the expert has reliably applied the principles and methods to the facts of the case

I'll end this post with a quote that I think adequately explains the reasons for expert testimony and the reasons why the elements above are what they are:

“There is no more certain test for determining when experts may be used than the common sense inquiry whether the untrained layman would be qualified to determine intelligently and to the best possible degree the particular issue without enlightenment from those having a specialized understanding of the subject involved in the dispute.”