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

Law Enforcement Testimony

Law Enforcement Officer Responsibility

In each phase of detection, you must determine whether there is sufficient evidence to establish “reasonable suspicion” necessary to proceed to the next step in the detection process. It is always your duty to carry out whatever tasks are appropriate, to make sure that all relevant evidence of DWI is brought to light.

The most successful DWI detectors are those officers who:

  • know what to look and listen for;
  • have the skills to ask the right kinds of questions;
  • choose and use the right kinds of tests;
  • fully document all verbal, visual, and sensory observations; and,
  • are motivated to apply their knowledge and skill whenever they contact someone who may be under the influence.

These officers are likely to make more arrests and help secure convictions.

Note-Taking Responsibility

A basic skill needed for DWI enforcement is the ability to graphically describe your observations. Just as detection is the process of collecting evidence, description largely is the process of conveying evidence. Your challenge is to communicate evidence to people who weren’t there to see, hear, and smell the evidence themselves. Your tools are the words that make up your written report and verbal testimony. You must communicate with the supervisor, the prosecutor, the judge, the jury, and even with the defense attorney. You are trying to “paint a word picture” for these people, to develop a sharp mental image that allows them to “see” what you saw; “hear” what you heard, and “smell” what you smelled. Officers with the knowledge, skills, and motivation to select the most appropriate words for both written reports and courtroom testimony will communicate clearly and convincingly, making them more successful in DWI prosecution.