When Do You Need An Expert Witness?

Posted by Michael E. Lyons | Sep 25, 2019 | 0 Comments

In trial, you should never go it alone if you don't have to. Sometimes the best defense requires the testimony of an expert (or two).

What is an “expert witness”?

There are two types of witnesses in litigation: a lay witness and an expert witness. A lay witness is someone who testifies from their personal knowledge (think: “I saw Professor Plum with the knife in the Library!”). An expert witness is someone with special knowledge hired to provide their opinion for litigation (think: “From my training and experience, I can testify that to a degree of scientific certainty, the fingerprint found in the library belongs to Professor Plum!”).

In Maryland, like many state courts, an expert may be permitted to testify if their opinion would “assist the trier of fact to understand the evidence or to determine a fact in issue.” This means that the opinion of the expert must be relevant and necessary. When a judge is making that determination, they must decide:

  1. whether the witness is qualified as an expert by knowledge, skill, experience, training, or education;
  2. the appropriateness of the expert testimony on the particular subject; AND
  3. whether a sufficient factual basis exists to support the expert testimony.

Can you call an expert witness in a court-martial?

The standard in a court-martial is different than state court. An accused is entitled to expert assistance to aid in the preparation of his defense upon a demonstration of necessity. This, practically, is when an expert would be of assistance and denial of the expert would result in a “fundamentally unfair trial.”

Military courts have established a three-part test to determine if the assistance of an expert is necessary. It must be determined:

  1. why the expert assistance is needed;
  2. what the expert assistance would accomplish for the accused; AND
  3. why the defense counsel is unable to gather and present the evidence that the expert assistant would be able to develop.

In the military, the experts approved for trial are paid for by the government, at no expense to the accused.

There are many different types of expert witnesses. In fact, there is no actual accreditation or education requirement for expert witnesses, and sometimes an expert is simply someone familiar with the issues because of their training and experience. Occasionally, someone with a particular military specialty may be called as an expert in the field that the military trained them in, even if they have never testified before.

Something we have been seeing more and more frequently over the last decade or so are computer forensic experts. Considering the way people use technology today, the prosecution often needs to call a computer forensic expert to help them present evidence on a variety of charges.

For example, in a sexual assault or drug possession case, the prosecution may want to introduce text messages during a court-martial. If they have pulled the text messages off your phone (or someone else's) through a cell extraction, defense counsel may be entitled to a computer forensic expert of their own at the government's expense. These experts may testify as to how the messages were retrieved from the phone, or how the metadata provides locations and time stamps.

Your computer forensic expert will work alongside your defense counsel to see if there is something in the massive amounts of data pulled from your phone (or the phone of another witness) that might be helpful to your defense.

It is important you have an attorney who is familiar with expert witnesses: how to identify when they are needed, how to get you one, and how to use them to mount the best defense possible. At Patriots Law Group, we have handled countless cases with expert witnesses successfully. We look forward to examining your case to see if you need expert testimony – and more importantly, to see how we can help.

DISCLAIMER:  The information above is for informational purposes only and is not intended to serve as legal advice for any particular situation.  No attorney-client relationship is intended or created by this information and may not be relied upon based on the above-statements.  Each individual situation is different and therefore a consultation is necessary before any advice can be relied upon as appropriate and accurate for your situation. Please call Patriots Law Group at 301-952-9000 to set up a consultation if you wish to obtain specific legal advice concerning your situation.

About the Author

Michael E. Lyons

“As a veteran, I bring my core values of service, integrity, and excellence to every client, every case, every time.” Background: Michael E. Lyons (“Mike”) handles cases in Maryland and Washington D.C. fr...


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