Birchfield v. North Dakota

In Birchfield v. N. Dakota. William Robert Bernard, 579 U.S. 438 (2016), the Supreme Court of the United States considered how the Fourth Amendment applies when officers arrest suspected impaired drivers and then seek chemical testing.

The case involved state laws that made it a crime for a suspected drunk driver to refuse chemical testing after arrest. In one of the consolidated cases, Danny Birchfield was arrested in North Dakota after officers suspected him of driving under the influence. He was asked to submit to a blood test and was told that refusing the test was itself a crime. He refused and was prosecuted for that refusal.

In the Minnesota case involving William Robert Bernard, officers arrested Bernard for suspected impaired driving and asked him to take a breath test. He refused after being advised that refusal was a crime under Minnesota law. He was prosecuted for refusing the breath test.

The Court considered these cases together because they raised the same practical question for impaired-driving enforcement: after a lawful DUI arrest, when may police require a chemical test without first getting a warrant, and when may the state punish a driver for refusing?

The issue before the Court was whether the Fourth Amendment allows officers, without a warrant, to require a person arrested for drunk driving to submit to breath or blood testing as a search incident to arrest.

In plain English, the Court had to decide whether a lawful DUI arrest automatically gives police enough authority to demand a breath test or blood test without a judge’s warrant. The Court also had to decide whether a state may make it a separate crime for the driver to refuse that test.

The Supreme Court drew a clear line between breath tests and blood tests.

The Court held that warrantless breath tests may be administered as a search incident to a lawful arrest for drunk driving. The Court reasoned that breath testing is relatively minimal in its physical intrusion, reveals limited information tied to blood-alcohol concentration, and serves the important government interest of enforcing drunk-driving laws. Because of that, officers do not need a warrant to require a breath test after a lawful DUI arrest, and a state may criminally punish a driver for refusing such a breath test.

The Court reached a different conclusion for blood tests. A blood test is more physically intrusive because it pierces the skin and extracts a sample from the body. It also can reveal more private medical information than a breath test. Because of those greater privacy concerns, a blood test is not automatically justified as a search incident to arrest. In general, officers need a warrant for a blood test unless another recognized exception to the warrant requirement applies, such as exigent circumstances.

The practical rule from Birchfield v. N. Dakota. William Robert Bernard is that, after a lawful impaired-driving arrest, a warrantless breath test is generally permitted as a search incident to arrest, but a warrantless blood test is not justified on that basis alone. A state may criminalize refusal of a lawful breath test, but it may not impose criminal penalties for refusing a blood test when the only justification is implied consent and no warrant or valid exception exists.

For patrol officers, the main takeaway is that breath and blood tests must be treated differently. After a lawful DUI arrest, a breath test is generally the safer warrantless option under Birchfield because the Supreme Court approved breath testing as a search incident to arrest. If state law authorizes it, refusal to take that breath test may be charged as a crime.

Blood testing requires more caution. A DUI arrest by itself does not automatically allow a warrantless blood draw. If officers want a blood sample, the practical default should be to seek a warrant unless there is a specific, articulable exception to the warrant requirement. Natural dissipation of alcohol in the bloodstream is an important factor, but Birchfield does not say that dissipation alone always creates an emergency justifying a warrantless blood draw.

Officers should also be careful with implied-consent warnings. Telling a driver that refusal of a breath test is a crime is consistent with Birchfield when the breath test is legally authorized. But telling a driver that refusal of a blood test is a crime can create constitutional problems if there is no warrant and no valid exception. That warning may also affect whether any claimed consent to a blood draw is truly voluntary.

Supervisors and trainers should make sure DUI policies distinguish between breath and blood testing. Forms, implied-consent advisories, and report templates should match current state law and Birchfield’s constitutional limits. When in doubt about a blood draw, officers should document the facts supporting a warrant request or any claimed exigency, including time, distance, availability of a judge, medical circumstances, crash investigation needs, and other facts that may matter under the Fourth Amendment.

For detectives and prosecutors reviewing impaired-driving cases, Birchfield provides a key screening question: was the test a breath test or a blood test? If it was a breath test following a lawful arrest, the search-incident-to-arrest doctrine likely supports it. If it was a blood test without a warrant, the case needs closer review for a valid exception or voluntary consent that was not based on an unconstitutional threat of criminal punishment.