Banner for The Criminal Justice Systems: A Guide for Law Enforcement Officers and Expert Witnesses in Impaired Driving Cases


It is beyond the scope of this publication to provide detailed information regarding cross-examination (i.e., questions asked by the opposing attorney, the one who did not invite you to participate in this case). However, there are some general areas that will likely be addressed:

  • Your professional background and credentials, including education and experience (or lack thereof);
  • Attacks on the depth of your knowledge—of the subject matter generally and the facts of this case specifically;
  • Bias—“always” testifying for one side and “never” the other; and
  • “You’re being paid to be here today, aren’t you?” implying that money is the motive to get you to say whatever the hiring attorney wants you to say.

The best way to handle cross-examination is the same way you handled the direct. Answer truthfully, don’t get angry, don’t get defensive, and if you don’t understand a question, say so. If all else fails, remember: in the grand scheme of this case, while it might not seem like it to you, your honest testimony is important—to the defendant, to any victims, and to the integrity of the criminal justice system. Do the best you can. That’s all anyone can ask of you.

Potential Pitfalls

Some frequently encountered pitfalls include: a) relying too much on notes and reports; b) arguing with defense counsel; c) appearing to be too invested in obtaining a conviction; d) offering unsolicited and improper conclusions and opinion testimony; e) being non-responsive to the point of adding gratuitous comments; f) using too much jargon; and g) being overly defensive when in error. Maintaining your composure and professionalism throughout this process is not always easy, but it is always important.