DuPage County DUI AttorneyIn Illinois, breath alcohol tests or "breathalyzers" are commonly used to assess a driver's blood alcohol concentration (BAC). If someone's BAC is over 0.08 percent, they are intoxicated per se, or intoxicated according to the law. A BAC over the legal limit is not always required for a drunk driving conviction. However, having a BAC of 0.08 percent or more will certainly make the chances of conviction much more likely.

Many people have questions about the accuracy of breathalyzer tests. They may have heard rumors that these devices can be incorrect or even that diets like the keto diet can lead to higher-than-actual BAC results.

Are DUI Alcohol Breath Tests Accurate? 

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DuPage County DUI Defense LawyerAnyone who has been stopped on suspicion of drunk driving is familiar with alcohol breath tests or "breathalyzers." These devices are used by the police to determine if a suspect has been drinking. The officer instructs the driver to blow into the device. After a few moments, the device displays a number indicating the driver's blood alcohol concentration (BAC). Are these devices accurate? Can extraneous factors interfere with the device's ability to detect intoxication? Can an individual charged with driving under the influence (DUI) avoid conviction if the breath alcohol device results were incorrect?

Factors That Can Interfere with Breath Alcohol Tests

Breath alcohol tests determine a person's BAC by analyzing the amount of alcohol on their breath. However, these tests are not infallible. Various circumstances can interfere with the test and lead to inaccurate or unreliable results.


Being involved in a car accident is a very stressful experience. But being involved in a car accident when you have been drinking can also turn into a criminal case. Although your first instinct may be to panic or even run away, there are steps that you should take in order to protect yourself in the event you will be arrested and charged with DUI.

Naperville DUI Defense LawyerA conviction for driving under the influence (DUI) can lead to significant administrative and criminal penalties. These penalties are especially harsh if you are convicted of aggravated DUI or you have been convicted of drunk driving one or more times in the past. DUI can lead to the loss of your driver’s license, heavy fines, and even jail time. However, being charged with DUI is not the same thing as being convicted of DUI. If you or a loved one were recently arrested for allegedly drunk driving, it is important to understand the potential defenses to this serious charge.  

The Results of Your Blood or Breath Alcohol Test Were Wrong

In 49 out of 50 U.S. states, the blood alcohol limit is 0.08 percent. This means that a person is automatically considered to be intoxicated if his or her BAC is above this limit. Usually, BAC is determined by a breath test such as a breathalyzer. These tests can be inaccurate for several reasons, including:

Naperville IL DUI defense attorneyDriving under the influence may result in significant penalties in Illinois, including driver’s license suspension, mandatory alcohol education classes, and in some cases, even jail time. DUI penalties are especially severe if there are certain aggravating circumstances present or it is not the defendant’s first DUI. If you or a loved one was arrested and charged with drunk driving based on the results of a chemical blood alcohol content (BAC) test, you may wonder if these test results may be disputed.

Contesting the Result of a Breath Alcohol Test

In Illinois, a driver is intoxicated “per se,” or automatically considered to be intoxicated, if his or her blood alcohol content is 0.08 percent or greater. Most police officers carry a portable breath test often referred to as a breathalyzer. These preliminary tests are typically used to establish probable cause for the DUI arrest. However, the results of a preliminary roadside BAC test alone are not enough to secure a conviction. Usually, after someone is arrested for DUI, they are issued a secondary test at the police station. These evidentiary tests are considered to be more reliable than the roadside test. However, several issues can cause a BAC test to be inaccurate, including:

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