Saturday, June 3, 2017

Defending Against Breathalyzer Results in a DUI

A DUI may be charged in two ways.  The first is that a person has drunk any amount of alcohol so that it impairs his or her ability to operate a motor vehicle safely.  The second is that the person is driving a vehicle with a blood alcohol concentration over .08.  Proving either of these propositions is sufficient to convict a person for DUI.  If both propositions are proven then the charges are merged into one crime of DUI.

Of the two charges the breathalyzer reading of .08 or higher is the most difficult to overcome.  Difficult but not impossible.  A breathalyzer reading of .08 or higher may be overcome by one of three methods.  The first is by a showing that the prosecutor has failed to prove that the breathalyzer machine was maintained and calibrated properly.  The law enforcement agency administering the breathalyzer must keep an accurate log of the required accuracy checks of the machine in conformity with the Illinois Administrative Code governing the use and maintenance of breathalyzer machines.
The second method would only apply if the results of the breathalyzer fell within the acceptable margin of error for the machine used.  In that case an argument can be made that the person was, in fact, driving with a BAC of under a .08 given the margin of error.  Of course the prosecution can make the argument that the BAC was actually higher on the other end of the error margin.  A counter to this argument is that since the burden remains on the State then the doubt should go to the defendant. 

Once a person is stopped for suspicion of DUI it takes about an hour for the police to conduct their field sobriety tests, make an arrest, transport the person to the station where the BAC will be conducted and then wait the required 20 minute period.  Depending on when the person had his or her last drink(s) a final argument can be made that during that hour more alcohol was seeping into the blood stream.  Therefore, at the time the person was driving and pulled over by the police his or her BAC was lower than when the person actually took the breathalyzer test. 

All three of the defenses mentioned above are fact specific and it is important to have an experienced DUI attorney review the facts to make a determination which defense is most likely to be successful in your case.  For additional information please visit

While every caution has been taken to provide my readers with the most accurate information and honest analysis, the information on this site is for general information purposes only.

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