How accurate are breath testing devices?

| Feb 18, 2020 | DUI |

For most people in State College, the embodiment of a charge for driving under the influence of alcohol is a person standing alongside the road blowing into a handheld breath testing device. Thus, when the measurement from such a device is being used against you to try and support DUI charges, you may think it pointless to try and dispute such an accusation. The assumption is that such devices are finely attuned, and thus reliably accurate (no matter your objections to not having been impaired at the time of the alleged offense). Yet that is not always the case. 

Indeed, according to research information shared by the National Motorists Association, breath testing devices can have a margin of error as high as 50%. While that means that a blood-alcohol content measurement of .08 (the legal limit in Pennsylvania) registered on a breath testing could potentially mean that your actual BAC is as high as .12, it could also be as low as .04. Given the consequences that can come with a DUI 15conviction, that such a margin of error may exist should provide more than sufficient reason to be skeptical of breath test results. 

How is such a high potential for error possible? Study results compiled by the Alcohol Pharmacology Education Partnership shows that breath testing devices rely on an assumed ratio of 2100:1 when generating readings (that being that the concentration of alcohol in your blood is 2100 times greater than that of your breath). In reality, however, that ratio can be anywhere between 1500:1 to 3000:1. Factors such as your age, sex, and genetic makeup can influence it, as well as your condition when the reading was taken. The calibration of the device itself can also prompt an erroneous reading. 

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