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Breakdown of a DUI, Part two: Sobriety and BAC tests

Once a police officer has stopped you on suspicion that you are driving under the influence of alcohol, there a number of tests that they can administer to determine whether or not you are impaired. Continuing our Breakdown of a DUI series, we'll take a closer look at what these tests are, how they work, and the rights you have concerning them.

Field sobriety tests

Field sobriety tests are designed to test factors such as a person's motor skills, hand-eye coordination, focus, and other capabilities that are affected by alcohol. Normally, these tests are easily passable by a sober person but become much more difficult to pass when you are impaired.

Common field sobriety tests include the officer asking you to walk in a straight line, balance on one leg, or focus your gaze on a moving object. According to one study, failing these tests indicates impairment in 91% of cases. However, most people who fail these field sobriety tests will still be given a breathalyzer afterward to be sure.

Blood alcohol content (BAC) tests

BAC tests - considered a more accurate measurement of impairment than field sobriety tests - are chemical tests designed to provide a measure of the alcohol in your bloodstream. Breathalyzers are the most common form of BAC tests, though there are four others that may be administered. These other four - urine, blood, hair follicle, and saliva test - are more accurate than a breathalyzer, however, they are also more invasive and more difficult to perform. Normally, these tests will only be conducted in extreme cases or if the suspect refuses to take a breathalyzer.

Whatever BAC test you are administered, you must test under .08% in order to legally operate a motor vehicle. Testing over .08% will lead to arrest in most all cases.

Can you refuse a sobriety test?

It is within your legal rights to refuse sobriety tests. However, the consequences of refusing a sobriety test are often severe. If you refuse to take a breathalyzer or perform a field sobriety test, you could have your driver's license automatically revoked and your insurance rates may increase drastically. Even after this, refusing to take a sobriety test may not stop an officer from arresting you under the suspicion that you are driving impaired. If you are arrested and appear in court, the prosecutor is allowed to tell the judge and jury that you refused to take a sobriety test, and this will be used as evidence against you. All said, refusing to take a sobriety test is likely not in your best interest.

Can you "beat" a BAC test?

The internet is full of tips on how to "beat" a breathalyzer. However, none of them actually work. In the end, if you have alcohol in your system, the BAC test is going to detect it no matter how many mints or onions you chew.

Can the results of a sobriety test be challenged in court?

The results of a sobriety test - BAC or otherwise - can absolutely be challenged in court. One common challenge is that the breathalyzer used to administer the test was not properly maintained. Breathalyzer's must undergo regular maintenance to ensure that they are working properly. A DUI lawyer will be able to look at the maintenance records of the machine that was used, and if those maintenance records are not up to date the results must be thrown out. This is just one of several ways the results of a sobriety test can be challenged.


You aren't likely to beat a sobriety test in the field, but there are ways for a skilled DUI lawyer to beat them in court. If you've been arrested for a DUI, we urge you to contact us as soon as possible. In the meantime, stay tuned for the next article in our Breakdown of a DUI series where we'll talk about the court procedure of a DUI case.

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