Infrared Technology Adopted to Measure BAC in New Jersey & Elsewhere

The New Jersey Supreme Court conducted a lengthy exploration of the technology utilized by the Draeger Alcotest 7110 (“Alcotest”) in the case of State v. Chun, 194 N.J. 54 (2007). The mission of the Court was to determine the reliability of the infrared/electrochemical device insofar as the Attorney General of the State of New Jersey had adopted the machine for use by law enforcement throughout the state. The Alcotest uses infrared technology to measure blood alcohol content (“BAC”). At the conclusion of the Chun case, the Supreme Court held that the infrared technology utilized by the Alcotest was reliable and that the results produced by the device would be admissible as proof of intoxication in New Jersey. Chun, supra., 194 N.J. at 148  (court held that “the device is sufficiently reliable so that the rights of all defendants have been protected”). Alabama, California, Massachusetts and Washington have also found the Alcotest 7110 reliable and admissible. Similar conclusions have been found in Pennsylvania, New York, Vermont, Florida, Oregon, and Georgia (among other states) with respect to other breath test devices that utilize infrared technology.

How Does the Infrared Technology Work?

The infrared component of the Alcotest essentially determines BAC by measuring the absorption rate of ethyl alcohol molecules contained in an individual’s breath. Ethyl alcohol molecules have quantifiable infrared light absorption rates at different levels. What the Alcotest 7110 does is to collect a concentrated breath sample and trap the air sample within a chamber. Infrared light is then introduced at one end of the chamber opposite a light detector at the other end. This process allows the device to quantify the absorption rate of the breath within the chamber. The higher the level of alcohol in the breath sample, the higher the absorption of the infrared light. A computer program then compares the level of absorption to statistical information that has been compiled regarding anticipated ethyl alcohol absorption at different levels. The comparison and correlation of the test data to the scientific data allows the device to determine the amount of ethyl alcohol in the breath sample. This translates into a BAC finding.

Infrared technology clearly appears to be one of the primary tools for measuring BAC in breath at this point in time. In fact, the National Highway Safety Administration has gone as far as to award $2.25 million to a company for the sole purpose of the developing an infrared in-vehicle blood alcohol sensor.