The image of one blowing into a handheld breath testing device on the side of the road is the near-universal representation of a drunk driving charge. Thus, having authorities in North Carolina using the results of such a test as evidence against you may seem as strong as a conviction.
Yet as many of our past clients here at The Law Offices of J. Darren Byers, P.A. can attest to, that is not the case. Breath test results are often viewed as unreliable (so much so that some courts do not even allow them as evidence). Challenging the results of such a test, however, requires that you understand exactly how such devices work (and how that introduces the potential for error into the equation).
Reviewing how alcohol gets on your breath
The exact type of alcohol you ingest when you drink is ethanol. Being a water-soluble compound, ethanol is able to pass through membrane surfaces through a process known as “passive diffusion.” This allows the ethanol you ingest to pass through the linings of the organs of your digestive system and enter into your bloodstream. Once in your blood, the ethanol then makes its way through your body via the veins, eventually ending up in your lungs. In your lungs, it comes in contact with oxygen, causing a small portion of it to vaporize into a gas (which then exits your body when you breathe).
Understanding your blood-to-breath ratio
It is this concentration of alcohol on your breath that breath testing devices measure. According to the Alcohol Pharmacology Education Partnership, these devices assume a static blood-to-breath alcohol content ratio of 2100:1. In reality, however, your actual blood-to-breath ratio can vary between 1500:1 and 3000:1, which lends credence to challenges of the accuracy of breath tests.
You can find more information on challenging DUI charges throughout our site.