Breath-Alcohol Concentration May Not Always Reflect the Concentration of Alcohol in Blood

A case is described of a 37-year-old man who was breath tested by the U.K. police following a traffic accident and was found to have a breath-alcohol concentration of 70 µg/100 mL—twice the U.K. legal limit. The defendant protested vigorously that he had not consumed sufficient alcohol to account for this excessive reading, and Widmark calculations, assuming his account of the alcohol consumed was accurate, suggested his contention was possibly correct. No evidence was obtained suggesting that the Lion Intoximeter used for the breath analysis was anything other than accurate. Alcohol loading tests were therefore carried out in the laboratory on two separate occasions, showing that breath-alcohol concentrations grossly in excess of the legal limit (140 µg/100 mL) were obtained when the amount of alcohol administered would have been expected to give a theoretical maximum of 35 µg/100 mL. A blood sample taken at the point when the breath-alcohol concentration was 70 µg/100 mL was shown to contain 54 mg of alcohol/100 mL of blood. Dental examination of the defendant showed that he had had extensive work carried out, including three bridges. A possible explanation, therefore, for these anomalous results is that the excessive breath-alcohol concentrations might be due to mouth alcohol retained in the bridges or periodontal spaces, although a careful fraud by the subject of this report cannot be ruled out. A case such as this, while rare, highlights the argument that defendants with high breath-alcohol concentrations who dispute the concentrations recorded should have the right to challenge the breath values by being offered the option of further blood or urine analysis, even though, in most cases, further analysis would most likely confirm the original breath reading.