Supreme Court Limits Warrantless DUI Blood Tests


The Supreme Court of the United States handed down a decision today in Birchfield v. North Dakota, which requires warrants for DUI blood tests and prevents states from criminalizing blood test refusals.

In a Fourth Amendment victory, SCOTUS struck down a law that criminalizes blood test refusals in cases involving suspected drunk drivers. The majority opinion stated that blood tests, unlike breath tests, are invasive and therefore require a warrant. Police can still require breath tests without warrants if they suspect drunk driving.

According to the Bismarck Tribune, the decision will have consequences for not just North Dakota, but Minnesota and 11 other states that have similar blood test refusal laws.

The Supreme Court cited cases like Skinner v. Railway Labor Executives’ Assn. and Schmerber v. California in asserting that taking a breath or blood sample is a search governed by the Fourth Amendment. Both breath and blood tests can qualify for exemption from the warrant requirement if they fall within the “searches conducted incident to a lawful arrest” doctrine.

What is the search-incident-to-arrest doctrine?

The search-incident-to-arrest doctrine or “SITA” allows police to perform searches without a warrant, so long as the search takes place after a lawful arrest and is done: for reasons of officer safety, to prevent arrestee escape, or to preserve evidence integral to the case.

When deciding when is appropriate to apply SITA, the court has previously considered two factors:

  1. The degree to which it intrudes upon an individual’s privacy
  2. The degree to which it is needed for the promotion of legitimate governmental interests

The Supreme Court used these two factors in a case involving a warrantless search of a cell phone in Riley v. California[2]. Because cell phones could not have been envisioned when the Fourth Amendment was adopted, the Supreme Court had to evaluate the case using these aforementioned principles. They did the same in Birchfield v. North Dakota, and found that while breath tests do not implicate any significant privacy concerns, blood tests do. Consequently, blood tests cannot be required without a warrant [3].

Blood Tests vs. Breath Tests

In its opinion, the Supreme Court compared breath tests with blood tests to determine the degrees to which both intrude upon an individual’s privacy. It found that:

  • Breath testing machines impose no greater privacy violation than DNA cheek swabs (Maryland v. King) or fingernail scrapes (Cupp v. Murphy)
  • Breath tests do not create any biological DNA sample to be held in the government’s possession
  • Taking a breath test is unlikely to embarrass the arrestee in the same way as a blood test would

While it was determined that breath tests do not impose an intrusion onto a person’s privacy, blood tests do.

Removal of Criminal Penalties for Blood Test Refusal

Criminalizing blood test refusal was implemented to further state efforts to combat drunk driving, but the Supreme Court decision now prevents motorists from being criminally punished for refusing to submit to a blood test based on legally implied consent to submit to them.

Refusal to submit to a blood test can no longer be criminalized, but the court did not limit civil penalties for blood test refusal, like license suspension.

The Supreme Court opinion in Birchfield v. North Dakota was delivered by Justice Alito, joined by Justices Roberts, Kennedy, Breyer, and Kagan. Justices Sotomayor, Ginsburg, and Thomas concurred in part and dissented in part. Birchfield v. North Dakota was filed together with Bernard v. Minnesota and Beylund v. Levi Director, North Dakota Department of Transportation. Read the full opinion here.