Updated on February 3rd, 2021 at 10:49 pm


If you have been pulled over and charged with a Wisconsin OWI, even though your Blood Alcohol Concentration (BAC) was under the legal limit, contact Wisconsin OWI Defense Attorney Nathan J. Dineen.  Law enforcement officers assume a driver’s BAC was higher during the time of driving compared to when the test was taken, ultimately charging the driver with a Wisconsin OWI.  The assumed BAC at the time of driving is derived through a method known as Retrograde Extrapolation.

What is Retrograde Extrapolation for a Wisconsin OWI?

Retrograde Extrapolation is a method, expressed through a mathematical equation, which estimates a driver’s BAC at the time of the incident by adding the BAC at the time of the test to the hourly rate of alcohol elimination multiplied by the number of hours between the incident and test times.   The equation estimates a driver with a BAC of .07 at the time of test (2.5 hours after the incident) would have had a BAC of .1 at the time of driving.

Wisconsin OWI Retrograde Extrapolation Issues

When a person consumes alcohol, the body first absorbs the alcohol, processes it, and then eliminates it from the body.  The use of the Retrograde Extrapolation equation for a Wisconsin OWI assumes the driver is in the elimination phase; however, some drivers may still be in the absorption phase when driving.  This means the driver’s BAC would have been lower at the time of driving than at the time of testing.  Also, there are many Factors which affect alcohol absorption and elimination, which are not taken into account when a law enforcement officer charges a driver with a Wisconsin OWI with a BAC under the legal limit.  With so many unknown factors influencing BAC, the Retrograde Extrapolation method is unreliable.

Hire Wisconsin OWI Defense Attorney Nathan J. Dineen

Were you charged with a Wisconsin OWI even though your BAC was under the legal limit?  Contact Wisconsin OWI Defense Attorney Nathan J. Dineen for an aggressive defense against your Wisconsin OWI arrest.  Attorney Dineen practices 100% OWI Defense in Wisconsin.  Contact him for a Free Case Review at 877-384-6800.