How to Win Your Case With a Breathalyzer Test of .115

Posted On September 02, 2008

What the BCA is afraid you'll find out

First, a little bit of background. I represent a client that got picked up for suspicion of DWI. The police gave him a breathalyzer test at 12:40 a.m. that returned a result of .110 (Minnesota's legal limit is .08). They gave him a second test four minutes later that returned a Blood-Alcohol level of .115. Seemingly, his proverbial ship is sunk, right?

Think again. After being released by the police, my client went and got a Blood-Alcohol test done on his own. At 3:04 a.m., 2 hours and 24 minutes after the first intoxalyzer test, his Blood-Alcohol level was as .046. Comparing the test results, this means his BAC dropped .064 since the 12:40 test, and .069 since the 12:44 test. These figures correspond to a drop rate of .0267/hour and .0296/hour respectively.

Now, lets look at the science behind blood-alcohol levels. Studies have shown that the average dissipation rate for BAC is .015/hour. The average range, dependent upon a number of factors (age, weight, sex, how quickly the drinks were consumed, etc), is .01 to .02/hour. Clearly, my client's dissipation rates fell well outside this average range. Even at the very edges of the realm of possibility, alcohol will leave your body at a rate of .009 to .03 per hour. This dissipation rates shown above barely fall within that range.

What does this mean? To put it simply, it's another piece of evidence that breathalyzer results are not infallible. So where do we go from here? Now that there is evidence of doubt about the reliability of the tests, lets work backward and see where that gets us. As I said, at 3:04 a.m., a Blood Alcohol Analysis returned a result of a .046 BAC. If we take that test result and work backward to the legal limit, we'll find where his BAC may have actually been when the police arrested him. Minnesota's legal limit is .08 BAC, .034 higher then his 3:04 a.m. test. Taking that difference and dividing it over the 2 hours 24 minutes between the first and third test, you get a dissipation rate of .0142/hour. While this is within the normal range (it's almost the average rate exactly), it means there is almost a 45% chance that at 12:40, when the police arrested him, his BAC was below the legal limit. 45 percent is clearly reasonable doubt.

Charles A. Ramsay

Attorney at Law


450 Rosedale Towers

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Roseville, MN 55113

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