How does a prosecutor prove general impairment DUI charges in chemical test refusal cases?

General impairment DUI charges are proven through circumstantial evidence. In many cases, the driver also admits to having consumed alcohol or having taken drugs. Depending upon the facts and circumstances, an admission to drinking can be suppressed in a DUI case, but, if the admission is not suppressed, the statement is damning evidence that the person drank alcohol or took drugs.

With charges involving alcohol, the investigating officer often testifies about general signs of intoxication that were noted on the DUI suspect, such as an odor of alcohol on breath; bloodshot, glassy eyes; slurred speech; difficulty standing or swaying; and fumbling or dropping paperwork. If the officer administered Standardized Field Sobriety Tests (SFSTs), the officer would testify as to the person's inability to perform the tests satisfactorily. The officer would also testify as to any erratic driving, such as crossing the lines on the roadway, varying speed, almost striking objects near the roadway, failing to stop at a designated stop line, and failure to make a turn in a normal manner.

With regard to prosecuting a general impairment drug-DUI case, many Pennsylvania prosecutors try to use a Drug Recognition Expert (DRE). The DRE is supposed to administer a 12-step procedure that is meant to identify drug impairment in the DUI suspect. The admissibility of DREs as expert witnesses is an area of the law that is currently being challenged in Pennsylvania. Many courts in other states have held that DRE testimony is admissible and that the officer can be present "expert opinions" regarding a person's impairment, but other states have held that DRE testimony regarding "impairment" is not admissible.