06 Jul How Accurate are Blood and Breath Alcohol Tests
Recently in Texas, hundreds of DUI tests were mishandled in a lab – but the problem isn’t exclusive to the Lone Star State. In fact, any time you have humans evaluating test results, there’s a strong potential for human error.
Aside from human error, though, there’s still one big question: how effective are blood and breath alcohol tests? If you’re charged with drunk driving, can your DWI lawyer question how accurate they are?
How Accurate are Breathalyzer Tests?
Breathalyzer is actually a brand name. Police departments don’t always use that brand; there are many other breath alcohol testing devices that serve the same purpose.
They’re not extremely accurate, though – even if the machine is working properly. Some studies have gone so far as to determine that readings can vary by about 15 percent from actual blood alcohol levels. The same study showed that at least 23 percent of the people tested will show results that say they have more alcohol in their breath than they do in their blood.
In a study conducted by the Wisconsin State Laboratory of Hygiene, researchers found that only 33 percent of breath test results matched the corresponding blood test results.
How Accurate are Blood Alcohol Tests?
Blood alcohol tests are known to be more effective than breath tests, but they’re not always accurate, either.
The main thing that ruins the accuracy of a blood alcohol test is that they sit for too long. When that happens, the blood congeals, coagulates or decomposes. That can lead to a false high reading.
Sometimes the results are misinterpreted by careless handlers, and sometimes errors occur in which blood samples are switched. However, these instances are uncommon. For the most part, blood alcohol tests are generally accurate.
Very Ineffective Tests: Urine Tests
Most jurisdictions don’t use urine tests to determine how much alcohol is in a person’s system. Usually, these tests are only used when blood and breath tests are unavailable. Studies have shown that these tests can be wildly inaccurate, so they’re generally only used as a last result.