You had several drinks at the bar before you drove home. Police stopped you for a moving violation and arrested you for DUI.

At the police station, you blew the breathalyzer. The reading was over the legal limit. Your friend, who was a passenger in the car, swears that you did not show any signs of impairment when you were driving.

With the help of an expert, it may be possible to prove that your blood alcohol was actually lower at the time you were driving. How?

Your body absorbs alcohol on a curve. After drinking, your blood alcohol rises and then starts to fall. These are called the absorption and elimination phases. With the help of an expert, your attorney can use a technique called retrograde extrapolation. The expert will look at a variety of factors such as when and what you drank, your size and whether you ate in order to calculate an approximate blood alcohol result for the time you were driving.

If you were in the absorption phase when you took the breathalyzer, your attorney can argue that your blood alcohol was actually lower at the time you were driving.

Be aware that the state is highly unlikely to dismiss your case based on your expert’s opinion. The state will want their own expert, and you will still have to battle it out in court. But in some cases, it is possible to prove that you were not driving under the influence after all.

If you are charged with DUI or a related offense in Illinois, contact an experienced DUI attorney immediately. Even if the evidence against you is overwhelming, an attorney who is respected at the court house may be able to negotiate a better plea agreement than you could on your own.

If you have questions about this or another related criminal or traffic matter, please contact Matt Keenan at 847-568-0160 or email

(Besides Skokie, Matt Keenan also serves the communities of Arlington Heights, Chicago, Deerfield, Des Plaines, Evanston, Glenview, Morton Grove, Mount Prospect, Niles, Northbrook, Park Ridge, Rolling Meadows, Wilmette and Winnetka.)

About mdkeenan

A criminal and school law attorney with over 17 years of experience, I have successfully represented clients all over the Chicago area. My practice includes DUI, felony, criminal, misdemeanor, homicide, internet crime, retail theft, traffic offenses, cyberstalking, drug crimes, weapons violations, domestic battery and juvenile crime. I also represent families involving school cases. My clients come from all over the Chicago area including Skokie, Wilmette, Niles, Northbrook, Glenview, Evanston, Winnetka, Highland park, Northfield, Park Ridge, Des Plaines and Mount Prospect. I am a member of the ACLU and the Illinois State Bar Association. I serve as a volunteer for First Defense Legal Aid. Se habla espanol.
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