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Breaking down breath test accuracy

On Behalf of | Mar 3, 2020 | DUI Charges

It may be widely assumed by many people in Vista that challenging the results of a breath test used to support a drunk driving charge is a fruitless pursuit. Given that such a result is often what law enforcement officials used to justify arresting one for driving under the influence, it may be assumed that such tests are beyond scrutiny. Yet that is not the case. Indeed, according to information shared by the American Motorists Association, breath testing devices may have a margin of error as large as 50 percent. 

Such an error window could conceivably leave one who might have been well under the legal limit when checked for alcohol intoxication facing potentially sever criminal penalties. How is this possible? The wide margin of error for breath test may be largely due to the fact that while there is scientific reasoning supporting the idea to test for one’s blood-alcohol content using their breath, the devices used to do so rely on an assumption to generate readings. That assumption (per research data shared by the Alcohol Pharmacology Education Partnership) is 2100:1 (that is, for alcohol content of one’s blood will be 2100 times greater than that of their breath). 

In reality, however, the ratio in most people can range from 1500:1 to 3000:1. These discrepancies can be due to biological factors (such as a person’s gender) as well as their physical condition at the time of an alleged DUI offense (such as how much food was in their stomach that might absorb alcohol. Whatever the reason for an error may be, it may be easy for many to see why breath test results can often be successfully argued to exclude as evidence in a trial determining if one truly is guilty of DUI.