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Are Blood Alcohol Tests Ever Wrong?

 Posted on May 05, 2023 in DUI

Joliet Criminal LawyerIllinois law considers a driver to be intoxicated per se, or intoxicated according to the law, if he or she has a blood alcohol concentration (BAC) of 0.08% or greater. A blood alcohol concentration of over the legal limit is not always required for a drunk driving arrest, but having a BAC over the limit will certainly make it much harder to beat a DUI charge.

There are two main ways that police officers and prosecutors demonstrate a driver's intoxication level: breath alcohol tests and blood alcohol tests. Blood testing is generally considered to be he most reliable way to determine a person's blood alcohol concentration. However, it is possible for a blood alcohol test to be incorrect.

Contamination of the Blood Sample

Blood alcohol tests involve using a syringe to draw a small quantity of blood from a person's body. Next, the blood is tested in a laboratory to determine the amount of alcohol in the sample. If the blood sample is contaminated, this can throw off the results. For example, if the person who administers the blood test uses an alcohol swab to clean the area and does not let the alcohol dissipate before conducting the blood draw, some of the alcohol may get into the blood sample, artificially increasing BAC.

Fermentation of the Blood Sample

Another potential issue that can invalidate a blood test is fermentation. Just as fruit juice can eventually turn into wine, the compounds contained in the blood can ferment over time, increasing the amount of alcohol in the blood. If a sample of blood is incorrectly stored or left to sit for too long, it may no longer be a reliable indicator of blood alcohol concentration.

Rising Blood Alcohol Defense

Even if a blood test is correct, an individual's BAC is not necessarily the same several hours after a DUI arrest as it was during the arrest. One potential defense against drunk driving charges is the rising blood alcohol defense. Because of the way alcohol is metabolized by the body, an individual's blood alcohol concentration rises over time and continues to rise even after the person stops drinking.

It is possible for a driver to be under the legal limit at the time that he or she was pulled over by police, but over the legal limit one or two hours later.

Contact our Joliet DUI Defense Lawyers

Blood tests and breath tests are not perfect, and various issues can lead to invalid results. If you or someone close to you was arrested for drunk driving, contact our Joliet drunk driving defense attorneys for help presenting a strong defense. Call McNamara Phelan McSteen, LLC at 815-727-0100 for a free initial consultation.




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