Is it legal for the police to draw your blood when stopped for a DUI?

The answer, of course, depends on the specific laws in your state. Most states have what is called an “implied consent” law. That means when you get your driver’s permit and/or license, you sign papers agreeing to follow all of the traffic laws in your state.

There’s a good chance your state has an implied consent law that says you have consented in advance to being tested for alcohol or drugs in your system if stopped by the police and arrested for driving under the influence of drugs (DUI) or driving while intoxicated (DWI). The police have the right to choose how the test will be done – either through a breathalyzer, urine or blood test. The breathalyzer is most common and can be done on the spot. If your blood alcohol content (BAC) is higher than your state’s minimum (usually .08) then you’ll receive a ticket and could be arrested and taken to jail.

Culpeper County Sheriff’s Office (Flickr)

The police may decide to get a urine sample or do a blood draw. These are usually done at the police station by a trained officer or law enforcement personnel. There’s always a chance that the case could end up in court and qualified witnesses are needed to support the state’s case. In the case of a minor, the same rules apply but courts have ruled that obtaining a blood sample is a “search” under the Fourth Amendment. This means added protections are involved when a juvenile is arrested.

Either consent for the blood test is needed or the police need to obtain a search warrant from a court. If the juvenile driver consents, the results of the test may be challenged in court. Such factors as the juvenile’s voluntariness when giving consent for the test, his or her age, intelligence and the length of time detained by the police are factors in looking at the totality of circumstances. Courts have excluded test results if the juvenile’s rights are violated.

In a recent case in Arizona,* the results of a blood test were excluded at trial because the verbal and written consent given by the 16-year-old driver was not voluntary under the circumstances. Another factor is whether the juvenile’s parents were present and able to talk with their child before consenting to the test. The Arizona Supreme Court said that “Such an invasion of bodily integrity implicates an individual’s most personal and deep-rooted expectations of privacy.”

In 2013, the U.S. Supreme Court took up the issue of warrantless blood tests for DUI suspects. In Missouri v. McNeely** they ruled that the police must obtain a search warrant before forcing a suspect to submit to a blood draw. The only exception is that if the situation is so compelling that they will lose the opportunity to obtain a true reading by the delay in obtaining a warrant. The decision is made on a case-by-case basis. They said that the dissipation of alcohol in the blood as time passes is not justification for a warrantless blood test.

Take a look at your state’s implied consent law before getting behind the wheel. You should be aware of what you’ve agreed to when getting your license. Simply Google your state’s name and “implied consent law” for the details.

*State of Arizona v. Butler/Tyler B. (May 31, 2013) Arizona law A.R.S. 28-1321

**Missouri v. McNeely, 133 S.Ct. 1552 (2013).