Rules for Breath Tests in DWI Cases

Published for NC Criminal Law on March 28, 2018.

The easiest way for the State to prove impairment in a prosecution for impaired driving is by introducing the results of a test of the defendant’s breath. Such test results are admissible without the foundation that would otherwise be required for this kind of scientific evidence so long as the testing was carried out in accordance with statutory and administrative rules governing implied consent testing. G.S. 20-139.1(b). Because the rule allowing breath test results to be introduced into evidence is relied upon so often, I thought it might be helpful to review the admissibility rule and the requirements for such tests. There are two admissibility rules set forth in G.S. 20-139.1. The first applies to chemical analyses generally. It provides that in an implied consent case, a person’s alcohol concentration or the presence of any other impairing substance in the person’s body as shown by a chemical analysis is admissible in evidence. G.S. 20-139.1(a). A chemical analysis is a test of a person’s breath, blood or other bodily fluid or substance to determine the person’s alcohol concentration or presence of an impairing substance carried out in accordance with G.S. 20-139.1. G.S. 20-4.01(3a). The second rule applies only to breath tests. It provides that a chemical analysis of the breath administered pursuant to the implied-consent law is admissible in any court or administrative hearing or proceeding if (1) it is performed in accordance with the rules of the Department of Health and Human Services, and (2) the person performing the analysis had, at the time of [...]