Inaccurate Breath Test Results Part II
The BAC Datamaster suffers from several problems. Although the device is supposedly accurate to 0.004, that accuracy is premised on laboratory conditions using controlled samples. Introducing a police officer as the breath test operator and a live person as the test subject, test results can reveal wildly deviating results. The Michigan Breath Test Operator Training Manual provides an example of three test results produced registering a 0.17, followed by 0.11, followed again by 0.17. That's a range of inaccuracy of 0.06, nearly the legal limit itself.

The BAC Datamaster can also display several error messages, and the police are specifically instructed not to take the unit out of service. This includes temperature error, which can dramatically alter a breath test score, calibration errors that obviously undermine the integrity of the breath test results, and even an error message “FATAL SYSTEM ERROR.” Without knowing whether the BAC Datamaster displayed a “FATAL SYSTEM ERROR” on the date of a breath test, judges, prosecutors and most defense attorneys accept the Datamaster results as reliable.

Continue for more information