A person can still testify even if that person may have been under the influence of drugs or alcohol at the time of the event. The issue is one of credibility and whether or not that person's perception of the events in question, memory, and judgement during the event they perceived is credible or not. The veracity/truthfulness/credibility of a witness is something that a Judge and or Jury can take into consideration during a trial, which means that an attorney can attack their credibility based upon the witness being drunk or high off drugs during the event(s) in question.
Answered on Oct 30th, 2012 at 9:53 PM