Cincinnati DUI Breath Tests And Reverse Extrapolation

If you are arrested for a Cincinnati DUI / OVI and submit to a breath test – the prosecutor now has some strong evidence against you.  In Ohio, it is illegal to operate a motor vehicle with a breath test that is .08 or greater at the time of operation

The law provides that as long as the breath sample is taken within three hours of operation, the prosecutor can admit that test result and it can be used without an expert witness to establish the breath test result at the time of operation.

One of the defense available is commonly referred to as reverse extrapolation.  This occurs when a breath test taken at the police station, after the operation and the defense argues that the breath test result at the time of operation was below a .08.  Or at least there is a reasonable doubt as to whether or not it was a .08 or greater.

This defense is valid and useful, but certain facts must be brought out during the trial before the argument can be made in closing.  It may be possible to use the state’s witnesses as experts or it may be necessary to call an expert witness to testify during the defense’s case.


If you or a family member have been arrested for DUI or OVI in the Greater Cincinnati area and need assistance with an upcoming court appearance in Butler, Clermont, Hamilton or Warren Counties, give us a call at our 24 Hour Emergency Number at 513.333.0014 for affordable and professional help.

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