Blood Alcohol Content

Each state has laws regulating legal amounts of blood-alcohol concentration (BAC). BAC is determined through blood, urine, or breath tests when a driver is suspected of intoxication. The breath test is conducted by using a device called a breathalyzer and can be administered roadside or in a law enforcement detention center, while blood and urine tests can be administered at a hospital or in a law enforcement detention center.

While most states have a legal limit of .08 percent BAC for those over age 21, some allow .10 percent. Proof of a BAC over the legal limit for that particular state is referred to as ‘per se intoxicated,’ meaning that this is the only proof necessary to convict a driver of DUI or DWI.

In many states, if a driver is under 21 years of age, the allowable BAC is usually lower than for that of an adult, and the BAC may even be zero. In ‘zero tolerance states,’ any positive alcohol testing for the driver (which is actually .02 percent BAC or above) will result in conviction of DUI or DWI and has more serious consequences, even if the driver has not reached the maximum legal BAC limit.

With a breath test, infrared light passing through the machine determines the blood-alcohol content (BAC). The results of breath testing for blood-alcohol content (BAC) are fairly accurate if administered properly. Law enforcement officers are trained by the National Highway Traffic and Safety Administration (NHTSA) to administer these tests.

A breath test machine can give an inaccurate reading if the driver has had certain substances in their mouth just prior to the test. Alcohol-based mouthwash and even sugar-free products could distort breath test readings. Many states have minimum mandatory penalties for drivers convicted of DUI with a particularly high BAC. In many states this level is .18 percent above the legal limit. The enhanced penalties vary between states, but possible repercussions include vehicle impoundment or installation of an ignition control device. Your driver’s license could be immediately suspended for a year if your blood-alcohol content is above the legal limit for your first offense, three years for your second offense, or five years for your third offense, just as an example of the laws in one state. Loss of your driver’s license for a particularly high BAC is a procedure through the Department of Motor Vehicles (DMV), and is separate from your criminal charges for drunk driving.