The Supreme Court of the United States (SCOTUS) heard a case earlier this year, Birchfield v. North Dakota, that involved two issues related to DUI breath test:

  • Do the police need a warrant to conduct a breath test on a suspected drunk driver?
  • Do the police need a warrant to conduct a blood test on a suspected drunk driver?

Breath Tests:

On the 23rd of June this year, the SCOTUS announced their decision. In a 6-2-majority opinion, Justice Alito held that police don’t need a warrant to conduct a breath test on defendants. Weighing several factors, Justice Alito explained that a breath test does not amount to a physical intrusion on the suspect’s body. Unlike blood or DNA, breath tests can only provide police officers with one piece of information: the concentration of alcohol in a person’s breath. There is nothing else a breath test can provide the police. Furthermore, there is nothing retained. Unlike a blood sample, which can be kept in a vial indefinitely, breath is fleeting and uncontainable. As such, the court held that states could conduct these warrantless tests and punish those for refuse to take it.

Blood Tests:

However, the court held by a 7-1 majority that blood tests do require a warrant. These tests, Alito wrote, are “significantly more intrusive” because they require a technician to puncture the suspect’s skin with a needle to draw the blood. The blood, unlike breath, can be retained indefinitely, and provides a wide range of information that goes beyond alcohol concentration. This means that state laws that penalize a suspect for refusing to take a blood test are unconstitutional. Accordingly, we can expect to see police departments emphasizing the use of breath tests over the intrusive blood tests in order to order to fight drunk driving.

For a more in-depth analysis, check out SCOTUS Blog’s article on this case. For the more adventurous reader, you can read the case itself:


This article is made available by Lee & Lee, PS for educational purposes only. The intent is to give the reader general information and a general understanding of the law. The article does not provide specific legal advice. Readers of this article should understand that there is no attorney client relationship between you and the writers. Furthermore, the article is not a substitute for competent legal advice from a licensed professional attorney in your jurisdiction.