When a police officer believes that a person is driving under the influence of alcohol, the officer may opt to test that person’s blood alcohol content, or BAC. In the state of Oklahoma, the legal BAC is 0.08%, but it should be noted that the effects of alcohol can be present in a driver long before he or she is at the legal limit.

BAC is the percentage of alcohol that is present in 100 deciliters of blood. For example, a blood alcohol content of 0.5% is equivalent to 0.5 grams of alcohol for every deciliter of blood. For some people, the effects of alcohol may be present once their BAC reaches just 0.02%. However, the effects of alcohol can vary depending on the person’s body fat percentage, body chemistry, weight and hydration level. Other factors can include what medications a person may be taking and their gender.

According to the National Highway Traffic Safety Administration, alcohol may have different effects at different BAC levels. For example, even at 0.02% BAC, a person may lose the ability to multitask. At 0.05% BAC, a person may have more difficulties focusing their eyes or track moving objects. At 0.08% BAC, a person may have impaired judgement and self-control, potentially making him or her more likely to cause an accident.

If a driver is determined to have a BAC of 0.08% by a blood or breath test, he or she will automatically be charged with a “per se” DUI. However, a person can also be charged with a DUI even if his or her BAC is lower than the legal limit if that person is found to be sufficiently impaired. A criminal defense attorney may help a person dispute the charge, which might include contesting the accuracy of the results of the breath or blood test.