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

Law Enforcement Testimony


One of the most critical tasks in the DWI enforcement process is the recognition and retention of facts and clues that establish reasonable suspicion to stop, investigate, and subsequently arrest persons suspected of driving or operating a vehicle while impaired. The evidence gathered during the detection process must establish the elements of the violation and must be documented to support successful prosecution of the violator. This evidence is largely sensory (sight, smell, hearing) in nature, and therefore is extremely short-lived.

You must be able to recognize and act on the facts and circumstances with which you are confronted. But you also must be able to recall those observations and describe them clearly and convincingly to secure a conviction. You may be inundated with evidence of DWI (i.e., sights, sounds, smells). You recognize this evidence, sometimes subconsciously, and on this evidence base your decisions to stop, investigate, and ultimately arrest.

The field notes provide the information necessary to complete required DWI report forms and assist you in preparing a written account of the incident. The field notes can also be used to refresh your memory if you are required to provide oral testimony.

One way to improve the effectiveness of your handwritten field notes is to use a structured note-taking guide. The guide makes it easy to record brief notes on each step of the detection process and ensures that vital evidence is documented.