Police departments throughout New Jersey use the Alcotest 7110 MKIII-c device to conduct breath tests on individuals suspected of driving while intoxicated (DWI) in order to determine a person’s blood alcohol content (BAC). Accuracy is critical for these devices, since state law imposes penalties based almost entirely on BAC.
State law creates two tiers of first-time DWI offenses based solely on BAC. A BAC of 0.08 percent or above creates a presumption of impairment. For first offenders, penalties are greater if the BAC is at least 0.10 percent. Blood testing generally provides a more accurate BAC result than breath testing, but as the Chun decision notes, it presents “obvious practical and logistical problems.” Breath testing requires neither a warrant nor a medical professional. All police departments in this state have used the Alcotest since 2008, some since 2005. The device can only provide an “estimation of BAC,” based on the passage of alcohol from the digestive system to the circulatory and then respiratory system. It uses two methods to measure alcohol concentration, which Chun describes as “infrared (IR) technology and electric chemical (EC) oxidation in a fuel cell.” The EC measurement is the more controversial of the two.
The Alcotest’s EC technology creates a catalytic reaction that oxidizes alcohol in the breath sample, creating an electrical charge that the device can measure. The accuracy of this measurement requires careful maintenance. A “simulator solution” used to calibrate the device must be maintained at a precise temperature. Chun requires the use of a thermometer that meets standards set by a federal agency, the National Institute of Standards and Technology (NIST).