Are Breathalyzers Reliable?
Breathalyzers are notoriously fraught with shortcomings, and numerous legal and scientific professionals have questioned their accuracy and reliability in recent years. In People v. Mertz, the primary issue involved was the timing of the test: Mertz was given a breathalyzer full hours after his crash. However, even when tests are taken immediately following an accident, breathalyzers continue to frequently produce “evidence” which ranges from questionable at best to wholly inaccurate at worst.
For example, in the summer of 2010, Washington D.C. city officials revealed that since 2008, nearly 400 people had been convicted of DWI on the basis of readings from breathalyzer machines which were improperly calibrated by local police. The District Attorney reported that all 10 of the devices used by city law enforcement were incorrectly adjusted, and routinely displayed readings which were a full 20% higher than what they should have been.
More recently, in August of 2013, retired Franklin County Municipal Judge Teresa L. Liston was appointed by the Ohio Supreme Court to review eight cases in which DUI defendants were challenging the BAC results of the Intoxilyzer 8000, a model commonly used by law enforcement throughout the country. On August 13, after a five-day hearing, Judge Liston ruled that the Intoxilyzer 8000 readings in question were “not scientifically reliable and the court, as a gatekeeper against unscientific evidence, must prohibit them from being introduced as evidence in this case.” While the Intoxilyzer 8000 remains in use today, more and more defendants are beginning to challenge its “presumption of reliability.”
Problems which can be detrimental to accurate breathalyzer readings include high heat or humidity, incorrect calibration, the rate at which the person being tested is breathing, and even certain medical conditions. For example, having diabetes can affect the levels of acetone in the body, which can subsequently produce inaccurate readings.