Your DUI Case Will Turn On Your Blood Alcohol Content
The central issue in almost every DUI case is whether your blood alcohol
content (BAC) is equal to or greater to than the statutory minimum. In
other words, if your blood alcohol content is above this minimum, you are
considered legally intoxicated and subject to DUI/DWI penalties. In the
United States, every state has a DUI/DWI statute that sets the legal BAC
threshold at .08 percent.
What is Blood Alcohol Content?
What exactly is your BAC? Simply put, it is the amount of alcohol in your
blood. A BAC test actually measures the weight of alcohol in a certain
volume of your blood, expressed as a percentage. The greater the level
of alcohol in your blood, the more your driving will be impaired. In fact,
although most states' laws provide that a blood alcohol content of .08
percent is the level at which you are considered legally intoxicated, some
studies conclude that a blood alcohol content as low as .02 affects your
ability to drive and increases the likelihood of an accident. The probability
of a crash begins to increase significantly at a blood alcohol content
of .05 percent and climbs rapidly above .08 percent.
How Is My Blood Alcohol Content Measured?
Your BAC is usually determined by breath, blood, saliva or urine testing,
which is typically performed shortly after you're stopped for suspicion
of DUI. Although police officers often use various field sobriety tests
once you're stopped for DUI, this type of test only tests your reflexes
and abilities not your BAC. In fact, if you fail a field sobriety test,
you can still be convicted of a DUI offense even if your BAC is below .08.
Blood testing is the most accurate method to determine your BAC. Blood testing usually involves the drawing of your blood by a doctor or other qualified medical professional.
Breath testing by the use of a breathalyzer is the most common type of blood alcohol test performed by law enforcement officials. A breathalyzer measures the alcohol level in your breath from the lungs.
To learn more about breathalyzers, take a look at our breathalyzer page.
How Can I Tell If My Blood Alcohol Content Is High Enough To Get Me In Trouble?
Obviously, the only way to accurately determine your BAC is to take a breath,
blood, urine, or other chemical test. However, there are some general rules
of thumb that allow you to estimate what your BAC is depending on your
weight and how much alcohol you have ingested. An average 170-pound man
must have more than four drinks in one hour on an empty stomach to reach
a .08 percent BAC. A 137-pound woman would reach .08 BAC after about three
drinks in an hour on an empty stomach.
Please understand, however, that these figures are rough estimates. Depending on your weight, your metabolism, how much you've eaten, and other factors, you may be legally intoxicated even if you have fewer drinks in your system than the average man or woman could legally handle. Accordingly, although we urge you never to drink and drive, don't rely on these rough estimates should you choose to drive with alcohol in your system.
There are also home breathalyzer kits that allow you to measure your own BAC. Again, these tests can be highly inaccurate, and we don't encourage you to rely on them.
Although .08 percent BAC is now the law in all 50 states, there are even lower thresholds for younger drivers in some states. In fact, in tough states like Illinois, there is a "zero tolerance" policy for drivers under the age of 21. In other words, if you are under 21 and have any level of alcohol in your blood, even .01 percent, you are subject to a DUI or DWI conviction.
