DUI Defense: Is Drinking After Driving a Viable Defense to DUI in Michigan? - November, 2014

In Michigan it is unlawful to operate a motor vehicle after drinking enough alcohol to be either impaired or intoxicated.  But what if you drive before you start drinking?  Is this a defense to a Michigan DUI / drunk driving arrest; and if so, then when might it be applicable?  A viable rising blood alcohol defense requires both a unique fact pattern and the appropriate underlying knowledge for applying the science of alcohol metabolism to these unique facts.

The way this potential defense usually arises is when the driver is found outside the vehicle at the time police arrive, such as when they arrive at a suspect’s home post-accident; or when the car has been disabled, such as when the driver’s car is in a snowbank or out of gas.  Subsequently, when the driver’s breath or blood is tested, they are found to be above the legal limit, but also claim to have been drinking after the completion of the driving.

Aside from the necessary lapse of time between the end of driving and the arrival of the police, there must also be a ready supply of an alcoholic beverage in sufficient quantity to account for the unlawful portion of the BAC.  However, evaluating the second part of the fact pattern – that is, the part associated with quantities of alcohol and total BAC – requires an understanding of the science of alcohol metabolism.

It is generally true that a person’s bodily alcohol level, or BAC, will continue to increase from the time the person starts drinking until they have reached full absorption.  According to Defending Drinking Drivers:1

Absorption of alcohol into a person’s body occurs through a process known as diffusion. Alcohol need not be digested by the body. Alcohol undergoes no chemical change in the body; rather, it is gradually absorbed into the blood, while it passes through the body’s digestive system. The quantity of alcohol present in the blood can then be measured.

The rate of absorption depends on numerous factors, including the amount of food the person has in his stomach. This is true primarily because food causes the pylorus to remain constricted or closed, and the alcohol will not be available for absorption until digestion is complete and the pylorus opens, allowing the food, and the alcohol, to pass into the small intestine. Generally speaking therefore, foods that take longer to digest, such as fats and proteins, will slow absorption more than less complex foods such as carbohydrates. Stomach emptying is also affected by the time of day, with the speed being faster in the morning.

Generally speaking, full absorption will take from 14-138 minutes to occur2.  In a rising blood alcohol defense, the facts must usually support an absorption rate closer to the low end of the spectrum.  Also, there must be a report, or at least an admission, to drinking enough alcohol to account for the total overall reported BAC.  Again, an analysis of this issue requires an application of the science to the facts.

It is generally agreed that a single unit of alcohol has the capacity to raise a person’s BAC by between .02 and .025.3  A unit of alcohol is one 12 oz. 5% beer, one 6 oz. 12% wine or 1.5 oz. of 40% spirits.

It should be noted that when a client reports that he or she has had three “drinks” this does not equate with three “units” of alcohol.  This is because most beer, particularly the increasingly popular craft beers, is far higher than 5% in ABV (alcohol by volume).  In fact, most craft beer contains between 7% and 12% ABV.  Consequently, a single 12 oz. craft beer at 7% ABV would be 1.5 units of alcohol.  If the driver consumed a draft, it was probably between 16 (standard pint) and 22 oz., requiring further upward adjustment.  The same is true of today’s wine, which is far more typically in the 13.5 – 15 ABV range.  Most mixed drinks also contain more than 1.5 oz. of 80 proof liquor.  Thus, obtaining an accurate drinking history, including exact type and size of drinks, is essential to evaluating this defense.

Looking at these various factors, it is evident that in order to utilize a rising blood alcohol defense, there must be a sufficient amount of alcohol consumed under circumstances where the alcohol can be rapidly absorbed such that it might contribute to the reported BAC.  This evidence, when combined with all the other evidence, must be sufficient to overcome the statutory presumption that the driver’s BAC at the time of the test was the same as it was at the time of the driving.4

A further word of caution must be given:  Before attempting this defense, be mindful of how alcohol elimination might impact your analysis.  “Once alcohol is consumed, the body automatically and immediately begins to eliminate it.  Elimination is accomplished in two ways, through excretion and through metabolism. Metabolism accounts for approximately 95 percent of the total elimination.”5  Normal clearance rates are between .01 and .02% per hour.  Some individuals can have clearance rates as high as .04%, while others as low as .006%.6

Consequently, in order to accurately and objectively determine if enough alcohol was consumed post-driving to account for the above .08 portion of the total BAC, an appropriate elimination rate must also be applied to your equation.  This means the longer the post-driving drinking spree, the more the total amount of alcohol that must be consumed.

A new unpublished Court of Appeals7 decision sheds light on the importance of understanding the science of alcohol metabolism.  The facts in this case are not discussed, but we know that the defendant claimed that there was appealable error related in some way to the defense raised, which was that the Michigan driver in this case drank after he stopped driving.  Furthermore, that the alcohol measured in his breath was not in his body at the time he drove.  It got there because he was drinking after he stopped driving.   The court in this case found that the evidence was insufficient to overcome the statutory presumption that the driver’s test results at the time of the test were the same as at the time of the driving.  Specifically the court indicated:

Here, defendant’s breath test results were .16 and .15.  As such, over one hour after defendant drove the vehicle; his blood alcohol level was double or nearly double the legal limit. Therefore, were it true that defendant drank three beers in the hour before police arrived at his home, it is unlikely that three beers would elevate defendant’s blood alcohol to the high levels it was measured at in defendant’s breath tests.

At least one state’s law supports the proposition that it is a defense to an OWI charge if one’s blood alcohol level can be attributed to drinking after driving.8  The Michigan court in Smith9 makes the point that the defense of after driving drinking is implied from an Alaskan statute but that Michigan’s statute makes no such implication.  The court does stop short of stating that such a defense (drinking after driving) is not allowed in Michigan, indicating further that delays between the time of drinking or driving and the time of the test go to weight rather than admissibility.  Specifically, “[t]o the extent that the passage of time reduces the probative value of the test, the diminution goes to weight, not admissibility, and is for the parties to argue before the finder of fact.”10  Also, a chemical test is not required in order to be found guilty of drunk driving in Michigan.11

Clearly the defense is a cognizable one in Michigan.  The problem with Smith appears to have been either that the beers were in fact “standard” beers, meaning 12 oz. beers with 5% ABV, or more likely, the finesse of this science was never elucidated for the court.  Had the beers been 7% craft beer from a 12 oz. bottle, then there would have been more than enough free alcohol available to account for more than .08 of the .16, thereby placing the driver below the legal limit.  The same would be true had the beers been 16 oz. drafts.

It should be obvious that the plight of the defense attorney in Smith12 could possibly have been avoided by first understanding the science of alcohol absorption, and then adequately educating the court.  Of course either would be a fruitless endeavor if the underlying facts do not initially support the defense.  This includes the unavailability of the alternative common law theory of operating under the influence of liquor, which requires no BAC at all.

Barone_39[cropped]by Patrick T. Barone

Patrick T. Barone is an adjunct professor at Cooley Law School where he teaches "Drunk Driving Law and Practice."  Mr. Barone is also the co-author of two books on DUI-related issues, including Defending Drinking Drivers (James Publishing), a well-known and highly respected multi-volume national legal treatise.  He is a frequent lecturer on trial practice and drunk driving defense tactics. He can be contacted on the web at: www.baronedefensefirm.com.


1.  Barone, Defending Drinking Drivers, Chapt. 2, §201.1 , James Publishing (March 2014).
2.  KM Dubowski, Absorption, Distribution and Elimination of Alcohol: Highway Safety Aspects, .Journal of Studies on Alcohol, Supplement No 10 (July 1985).
3.  See Jones & Holmgren, Age and gender differences in blood-alcohol concentration in apprehended drivers in relation to the amounts of alcohol consumed, 188 Forensic Sci Int’l 43 (2009).
4.  City of Plymouth v. Longeway, 296 Mich. App. 1, 5 (2012) (citing M.C.L. 257.625(1))
5.  Defending Drinking Drivers, supra, at §201.2
6.  See Fitzgerald and Hume, The Single Chemical Test for Intoxication: A Challenge to Admissibility, 24 Mass. L. Rev. 23 (1981).
7.  People v. Smith, No. 312508, 2013 WL 6670853 (Mich. Ct. App. December 17, 2013).
8.  Wynacht v. State of Alaska, No A-10631, Court of Appeals of Alaska (March 14, 2012).
9.  Id.
10.  People v. Wager, 460 Mich. 118 (1999).
11.  People v. Stephen, 262 Mich. App. 213, 219- 220 (2004)
12.  Id.