A number that you will hear time and time again associated with alleged DUI offenses in Fox Lake is .08. That is the near-universal blood-alcohol limit assigned to intoxication. That the measurement of the alcohol content of your blood, however, is what determines whether you are driving under the influence might seem confusing, as law enforcement officials do not test your blood after stopping you for suspicion of DUI. Rather, they test your breath. 

This begs the question of how your breath can provide an accurate measurement of the content of your blood. Per the Alcohol Pharmacology Education Partnership, the type of alcohol that you ingest when drinking is ethanol. This is a water-soluble compound that can pass through membrane surfaces in the body through a process known as passive diffusion. Thus, much of the ethanol that you ingest will eventually pass through the lining of the organs of your gastrointestinal tract and into your capillaries, and eventually, your veins. 

Once there, ethanol is then carried in your bloodstream to your heart, where it is then routed to the linings of the alveolar sacs of your lungs. Your lungs, of course, contain oxygen. Upon coming into contact with that oxygen, some of the ethanol molecules are vaporized into a gas, which is then expelled from your body as you exhale. As gaseous ethanol is exhaled, more is vaporized to maintain equilibrium with the liquid content still in your blood. 

With every breath, then, your blood-alcohol content is slowly lowering. Given the dynamic nature of this process, it may be difficult to replicate the results of a breath measurement test. This may call into question the accuracy of breathalyzer tests, as there indeed are assumptions involved with generating measurements in order to account for your BAC’s ever-changing volumes.