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Quantifying Alcohol Intoxication - .08 and the Law

 Posted on September 21, 2017 in Uncategorized

If you are like most people, you probably know that the 0.08 is the “magic number” regarding drunk driving. A person with a blood-alcohol content (BAC) of 0.08 or higher may face charges for driving under the influence (DUI), but many people do not really understand what that number actually represents. In addition, it may be equally surprising to know that you could face DUI charges even if your BAC is lower than 0.08.

Two Ways of Determining BAC

Contrary to popular belief, Illinois law does not define blood-alcohol content as a percentage. There are many websites and resources that indicate that a BAC of 0.08 means that .08 percent of that person’s bloodstream is alcohol. In Illinois, at least, this is not how BAC is defined.

According to Illinois law, alcohol concentration can be determined in two ways: as a ratio of alcohol to blood or as a ration of alcohol to breath. The Illinois Vehicle code states, “Alcohol concentration shall mean either grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath.” These numbers were established based on scientific research to be equivalent to each other. A person with .08 grams of alcohol per 210 liters of breath is presumed to also have 0.08 grams of alcohol in every 100 milliliters of blood. (The density of alcohol actually means that a person with a BAC of 0.08 has more than .08 percent of his or bloodstream comprised of alcohol.)

Exceptions to the 0.08 Rule

Today, all 50 states and the District of Columbia recognize 0.08 as the threshold of legal intoxication for non-commercial drivers who are of legal drinking age. It is important to realize that 0.08 represents the point where intoxication may be presumed. A person with a BAC of 0.08 is not at the limit—he or she is legally considered to be under the influence. A BAC of 0.078 is technically legal. Keep in mind, however, that there are situations in which a person can have a BAC of under 0.08 and still face penalties for driving under the influence of alcohol, including:

  • Any trace of alcohol or a BAC over 0.00 for a driver under the age of 21 creates the presumption of driving under the influence;
  • Any trace of alcohol of a BAC over 0.00 for driver operating a school bus;
  • A BAC of less than 0.08 and greater than 0.05, but other evidence such as slurred speech or reduced motor skills supports a DUI charge; and
  • A BAC of 0.04 or higher for commercial driver’s license holders.

The charges and potential consequences will vary based on the circumstances of each case and the driver’s history.

Call Us for Help

If you have additional questions about DUI charges in Illinois or if you have been arrested and are facing charges, our firm is ready to provide the guidance you need. Contact an experienced Joliet DUI defense attorney to discuss your case and your options. Call 815-740-4025 for a free consultation today.

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