If you are facing charges for driving while intoxicated in Memphis based off the results of a breath test, you may be asking yourself why is it that law enforcement officers measure your breath to determine the alcohol content of your blood. Would not a blood sample be more accurate? While yes, blood samples do tend to yield more accurate blood-alcohol content measurements, such a test cannot be conducted on the side of the road. Thus, a breath test done using a handheld device is all authorities may have to rely on. Knowing the details of how alcohol gets from your blood to your breath could potentially give you cause to challenge the charges against you.
According to the Alcohol Pharmacology Education Partnership, once you have ingested alcohol, the water-soluble ethanol molecules that give beverages their alcohol content separate and are able to pass through the lining of the stomach and small intestine through a process known as passive diffusion. They then enter into your bloodstream and are carried in the veins throughout the rest of your body, eventually arriving at your heart. Once there, they are then routed with the rest of the deoxygenated blood to the lungs, where they come in contact with oxygen. That oxygen causes some of the ethanol molecules to vaporize into a gas, which is then exhaled as you breathe.
The process continues, with sufficient ethanol vaporizing to maintain an equilibrium with the ethanol concentration of your blood. This means that with every breath, alcohol escapes your body and your BAC lowers. This is what contributes to the extreme margin of error attributed to handheld breath devices (and what may provide you with the basis of disputing a DWI charge).