What does BAC mean?

In every state in the United States—including Washington State—the legal limit for blood alcohol concentration (BAC) is 0.08 percent (except for CDL drivers driving a commercial vehicle at the time of arrest and underage drivers). If your BAC is 0.08 percent or above, it is highly likely you will be arrested for DUI. As you drink, your BAC rises, thus the correlation between BAC and impairment. DUI Driving Laws provides a chart which shows how BAC corresponds to a subject’s weight and number of drinks. As an example, a 160-pound person who has had four drinks would have a BAC of 0.08 percent—the legal limit. A “drink” is defined as 1.5 ounces of hard liquor, 12 ounces of beer, or five ounces of wine. It is important to keep in mind that these are only guidelines, as gender can affect BAC, as well as whether you ate prior to consuming alcohol, certain medications, and illnesses.

Blood alcohol concentration is typically measured through a breath test or a blood test. Police officer favor breath tests because blood draws involve burdensome procedures, as well as a warrant if the subject refuses. Blood BAC tests can take 6 months or more to be analyzed, while a breath test has instantaneous results. Blood alcohol is usually measured in grams of alcohol per 100 milliliters of blood, while breath alcohol is measured in grams of alcohol per 210 liters of breath. Factors which can potentially affect breath test results include variances in temperature, an improperly calibrated device, use of cough medications, mouthwash or an asthma inhaler, certain medical conditions, specific breathing patterns, diabetes, or the police officer’s failure to observe the driver for the required amount of time prior to testing.

A driver’s occupation can even potentially skew the results of a breathalyzer test—a person exposed to acetone at work (like painters), can have acetone in their system which can inflate breath test results. A blood draw is typically considered more precise than a breath test, however, a dispute could arise if the person who drew the blood was unlicensed, the equipment was not properly calibrated, the blood was not drawn within the required time period, the blood was not properly stored or preserved, or the custody chain of evidence was broken.

At a BAC of 0.04 to 0.06, most people will feel relaxed, and there may be minor impairments regarding reasoning and memory. With a BAC between 0.07 and 0.09 percent, mild impairments in vision, control, balance and speech may exist. When a person’s BAC is between .10 and .12, most people will experience slurred speech, loss of judgment and significant impairment of motor coordination. When BAC increases to .13-.15, most individuals will experience gross impairment of motor control, blurry vision, and major loss of balance, and many will experience anxiety and restlessness. With a BAC between .16 and .20, the individual may become ill, will have significant impairment of motor control, loss of balance, blurry vision, anxiety, and may exhibit all the signs and symptoms of what we generally call a “sloppy drunk.” Should an individual continue to drink, a BAC of .35 to .40 can result in a loss of consciousness and borderline coma, and a BAC over .40 will result in coma and likely death, due to respiratory failure. Contact us today with any of your questions about BAC. Our experienced DUI defense lawyers are here to help with your case.