Take a deep breath in. Now breathe out. These instructions sound like something a doctor would ask a patient to do, but it is the same instruction that an officer might give to a DUI suspect. As we’ve mentioned here on the blog recently, it’s that time of year when law enforcement is out on the roads in huge numbers. Based off of last year’s numbers, it is anticipated that over 13,000 law enforcement officers will be participating in holiday DUI enforcement and will be having contact with more than 100,000 drivers in Arizona this season.

How do Breathalyzers Work?

One of the methods often used to test a person’s blood alcohol concentration is a breathalyzer, which measures the alcohol concentration in the air that is exhaled from a person’s lungs. Like gas chromatographs that test blood samples for alcohol, these machines have to be checked and calibrated to ensure that they are producing reliable results.

Are Breathalyzers Trustworthy?

A recent decision from an appellate court in Ohio found that in determining whether to accept a breathalyzer’s results as trustworthy, you can’t just look at the test results from the weeks directly before and after a machine was calibrated (as had been commonly done); you have to look at the results a machine is producing over a larger span of time. The Ohio State Highway Patrol had been using a breathalyzer that had to be calibrated once weekly, but after looking into a particular machine’s records, attorney Kenneth Bailey was unsettled by what he found. “The test failed nine times in sixty days,” he stated about the machine that produced the results from his client’s breath test. The judge ruled to throw out the results, saying that a machine that falters this many times cannot be producing reliable results.

Whether using older technology like breathalyzers or the current “gold standard,” gas chromatography, to test a person’s BAC, it is imperative that these machines be regularly evaluated to determine if they are performing properly. To put this in perspective, if your laptop turned itself off, the first time it happened, you might just shake your head in frustration and turn it back on. But if it kept on doing this, you would probably be desperately looking into how to fix it or shopping for a new one! Just because your computer turns back on alright does not mean that it’s fine. These machines should not be treated any differently; they are producing the evidence that can help convict people of crimes. Before that happens, though, we need to be able to trust the evidence—and that means being able to have confidence in the technology that obtained it.