Since the advent of energy drinks in the U.S. marketplace, some defendants have claimed that positive breath alcohol test results have occurred due to the ingestion of non-alcoholic energy drinks. A variety of energy drinks were tested by gas chromatography and some 88.9% (24 of 27) were found to contain low concentrations of ethanol (5-230 mg/dL). Drinks were then consumed (24.6-32 oz) by volunteers to determine the extent of reaction that could be achieved on a portable breath-testing instrument. Eleven of 27 (40.7%) beverages gave positive results on a portable breath-testing instrument (0.006-0.015 g/210 L) when samples were taken within 1 min of the end of drinking. All tests taken by portable breath test, DataMaster, and Intox EC/IR II at least 15 min after the end of drinking resulted in alcohol-free readings (0.000 g/210 L). Affording subjects a minimum 15-min observation period prior to breath-alcohol testing eliminates the possibility that a small false-positive alcohol reading will be obtained.