Are DUI Tests Accurate?

If a police officer suspects that you are under the influence of alcohol, he or she will administer various tests, which include field sobriety tests, which are used to evaluate your physical and cognitive state, and chemical tests, which are used to determine your blood alcohol content (BAC). Chemical testing can include an evaluation of your blood, breath or urine to determined the amount of alcohol in your body.

The results of these tests can be vitally important in determining whether or not you are charged with a DUI or DWI, so it is definitely worth questioning their accuracy.

Field Sobriety Tests

Field sobriety tests can be inaccurate because there are several factors that can affect a person’s balance or cognitive ability. Obviously, being pulled over by the police is a distressing experience. In addition, the officer’s presumption that you were driving under the influence can add even more nervousness. As a result, a person could become disoriented and confused, which can lead to answering the officer’s questions incorrectly. Furthermore, if the officer administers the field sobriety tests on uneven or slippery pavement, that can affect your ability to perform the physical tests well. Finally, if the officer incorrectly administers the field sobriety tests, the results can be skewed. In Illinois, there is no legal consequence if you refuse to take these tests.

Chemical Tests

Chemical tests have varying degrees of accuracy, depending on which one you take. A breath test, or Breathalyzer, is only an indirect method of measuring your BAC. The results are based on how much alcohol is contained in only a portion of exhaled air, rather than how much is actually in your blood. Additionally, there are many outside factors that can impact the results of a breath test. For example, the use of mouthwash, a breath freshener or any substance that contains alcohol can affect the results. Stomach fluid contained in vomit or even a burp can impact the results with a false high reading. This is why police are supposed to watch a suspect for at least 20 minutes prior to administering a breath test, in order to make sure that person does not burp, vomit or put anything into his or her mouth.

Urine tests are less accurate than breath tests. A urine sample represents only a composite of a continuously changing blood alcohol content. The urine contained in a person’s bladder at any given time is an accumulation of secreted urine since the last emptying of the bladder. Therefore, a urine test tells much less about a person’s blood alcohol at a particular moment than a blood sample would.

The most accurate test used to determine a person’s BAC is the blood test. However, this test is not completely infallible. The blood sample could be mishandled, improperly preserved or left to sit around for too long a period of time before analysis, which can lead to a false high reading.

It is important to note that refusing to take a chemical test in the state of Illinois will result in the suspension of your license. If you refuse a chemical test, or if you are arrested for DUI, you need to help of an experienced Chicago DUI Attorney. For more information regarding your rights after a DUI arrest, contact Fred Mark Dry.


Recent Posts