MN Supreme Court: No correlation between blood and urine alcohol concentration needed for DWI

Published On: 9th February 2012

Yesterday in State v. Tanksley, the Minnesota Supreme Court held that to convict someone for driving while impaired, (DWI), a urine test for alcohol does not need to correlate to blood alcohol concentration. The Court based its decision on the fact that urine testing is one of three approved methods to determine alcohol concentration under MN DWI laws.

Tanksley’s argument was based on what has been known to DWI defense attorneys for quite some time; a first-void urine sample is a snapshot in time of a person’s alcohol concentration and does not accurately reflect blood alcohol concentration. Unlike Minnesota, most other states require the bladder be emptied before the urine is sampled to test for the presence of alcohol. The reason for this procedure is that that alcohol in the urine does not dissipate as quickly as alcohol is metabolized in the bloodstream. Therefore, a first-void urine sample can reflect a higher alcohol concentration than what is present in the blood that would affect the motor skills of a driver.

At the outset, the Court’s decision seems to contradict the requirement that the State must prove a defendant’s alcohol concentration was 0.08 or more at the time, or within 2 hours of the time, the defendant operated or physically controlled a motor vehicle to obtain a conviction for a DWI. However, the MN DWI law defines “alcohol concentration” as “(1) the number of grams of alcohol per 100 milliliters of blood; (2) the number of grams of alcohol per 210 liters of breath; or (3) the number of grams of alcohol per 67 milliliters of urine.” Therefore, under a strict reading of MN DWI statutes, it does not matter whether alcohol in the urine correlates to the blood alcohol concentration because the legislature has said that alcohol concentration in the urine is sufficient to convict someone for a DWI.

Coley Grostyan is a Minneapolis based DWI defense attorney who represents individuals charged with driving while impaired (DWI), and all other impaired driving related charges in the Twin Cities and surrounding suburbs, and throughout the State of Minnesota.



Law Office of Coley J. Grostyan, PLLC
701 Fourth Avenue South, Suite 300
Minneapolis, MN 55415


MN Supreme Court: No correlation between blood and urine alcohol concentration needed for DWI