In our last blog post, we discussed the difference between blood alcohol content (BAC) and breath alcohol content (BrAC). While police often insist that they are the same, BrAC is far easier to measure. However, it is also far less reliable than blood alcohol content.
Why Police Rely on Breath Alcohol Content Readings
When police investigate a potential case of driving under the influence (DUI), what they really want is a breath test or a blood test that shows the driver is at or above the legal limit of 0.08%. If they get this, the driver is per se “under the influence” for the purposes of 75 Pa. Cons. Stat. § 3802. This makes it far more difficult to defend against a subsequent DUI charge.
Breath tests, however, are far less intrusive to perform. While blood tests require a blood sample that can only be procured through an invasive medical procedure that literally pierces a suspect's skin, breath tests only require a breath sample that can be procured by capturing a driver's exhale. The relative simplicity of conducting a breath test and procuring a BrAC reading also makes them far easier to conduct on the side of the road during a traffic stop.
Environmental Factors Can Make BrAC Readings Inaccurate
However, the fact remains that BrAC merely mirrors BAC – the amount of alcohol on someone's breath is not always identical to the amount in their bloodstream. This can mean a driver's BrAC does not adequately indicate whether they are too “under the influence” to drive or not.
The amount of alcohol on someone's breath can get pulled away from their “true” BAC by environmental factors that generally make the BrAC readings much higher than they should be.
The most common environmental factor that can elevate a BrAC reading is the presence of latent alcohol in a driver's mouth. For example, if you swish mouthwash (which has an alcohol content nearly five times as high as a beer) and then immediately take a breath test, your BrAC reading will be very high as the alcohol in the mouthwash will still be lingering in your cheeks, gums, and tongue. As you wait, the latent alcohol in your mouth will dissipate until your BrAC, in theory, matches your BAC.
Another environmental factor that can elevate your BrAC is if you burp. Most of the alcohol that gets ingested when you drink goes to your stomach. When you burp, alcohol-laden air comes from your stomach, back up your esophagus, and into your mouth, creating a spike in your BrAC that does not reflect your level of inebriation.
These are just two of the ways that a breath test's results can be skewed against a driver and get them into legal trouble. All of them assume, of course, that the breath test is properly administered by the police officer. Unfortunately, this is not always a safe assumption.