Is it possible that I was intoxicated when I got tested for DWI, but not while I was driving? Will this make a difference in my DWI case in Pennsylvania?

Joanna

Philadelphia, PA

When a person has a Blood Alcohol Concentration (BAC) of 0.08 or more, the Pennsylvania law defines this as intoxication resulting to a person’s failure to normal use of mental or physical faculties. The time when the test was conducted can present a significant problem for either the prosecution or the defense (depending upon the circumstances). Usually, this problem arises in connection with breath and/or blood tests administered just about 45 minutes to 1 hour and 15 minutes after driving. Since the test is delayed, a person’s alcohol concentration at the time of driving may have been higher, lower or the same due to the absence of other information (i.e. the number and type of alcoholic drinks consumed, the time when the drinks were consumed.)

In order to know the relation of the test result to alcohol concentration at the time of driving, the prosecution may try to present an expert testimony. This process used by the expert is known as retrograde extrapolation where the he relates the test result back to the time of driving. Depending on the facts presented in your case, he may use his knowledge regarding alcohol absorption, distribution, and elimination to have the State’s extrapolation evidence excluded or to come up with issues of reasonable doubt in connection with that evidence.