Missouri v. McNeely

Missouri v. McNeely, 185 L. Ed. 2d 696, was a 2013 United States Supreme Court case about warrantless blood testing in drunk-driving investigations.

A Missouri police officer stopped Tyler McNeely after observing traffic violations that suggested impaired driving. During the stop, the officer noticed signs of intoxication and McNeely performed poorly on field sobriety tests. The officer arrested him for driving while intoxicated.

McNeely declined to submit to a breath test. The officer then took him to a hospital and directed medical personnel to draw McNeely’s blood without first getting a search warrant. The officer did not claim that there was a crash, an injured person, unusual delay, or some other special emergency beyond the normal fact that alcohol in the bloodstream naturally dissipates over time. The blood test showed a blood-alcohol concentration above the legal limit.

McNeely moved to suppress the blood-test evidence, arguing that the warrantless blood draw violated the Fourth Amendment. The Missouri courts agreed with him, and the case reached the Supreme Court of the United States.

The issue in Missouri v. McNeely was whether police may always take a nonconsensual blood sample from a suspected impaired driver without a warrant simply because alcohol naturally leaves the bloodstream over time.

In plain terms, the Court had to decide whether the natural loss of alcohol evidence creates an automatic emergency in every DWI case, or whether officers must usually get a warrant unless the specific facts show that getting one is not reasonably practical in time.

The Supreme Court held that the natural dissipation of alcohol in the blood does not create a per se, automatic exigent circumstance that excuses the warrant requirement in every drunk-driving case.

The Court recognized that a blood draw is a search under the Fourth Amendment. Because it pierces the skin and collects biological evidence from inside the body, it is more intrusive than many other investigative steps. As a general rule, a warrant is required for a nonconsensual blood draw unless an established exception to the warrant requirement applies.

The Court did not say that officers can never obtain a warrantless blood draw in an impaired-driving case. Instead, the rule is case-specific. Courts must look at the totality of the circumstances to decide whether exigent circumstances existed. The fact that blood-alcohol evidence is disappearing is important, but it is not enough by itself to justify skipping the warrant process in every case.

The practical holding is that officers should seek a warrant for a nonconsensual blood draw when they reasonably can. A warrantless blood draw may be justified if the facts show a true urgency, such as circumstances that make obtaining a warrant impractical without risking significant loss of evidence. But the prosecution must be able to point to more than the ordinary metabolization of alcohol.

Missouri v. McNeely means that officers investigating impaired driving should not assume that every refusal automatically permits a warrantless blood draw. If the suspect does not consent, and no other recognized exception applies, the safer constitutional course is to obtain a search warrant before ordering a blood draw.

The key question is not simply whether alcohol is leaving the suspect’s bloodstream. That is always happening in alcohol cases. The key question is whether the specific circumstances made it impractical to get a warrant in time. Officers should be prepared to explain the facts that created urgency, such as unusual transportation delays, the need to handle an accident scene, medical issues, limited staffing, or other circumstances that would meaningfully delay warrant review. Those facts need to be documented clearly.

The decision also encourages agencies to use efficient warrant procedures, including electronic or telephonic warrant systems where available. If a warrant can be obtained reasonably quickly, McNeely makes clear that officers generally should use that process before a compelled blood draw.

The case does not eliminate impaired-driving enforcement, and it does not prevent officers from making DWI arrests based on observations, field sobriety evidence, driving behavior, admissions, breath testing where lawful, or properly obtained chemical tests. It also does not decide every issue involving implied-consent laws or administrative penalties for refusal. Its core rule is narrower: natural alcohol dissipation alone does not automatically justify a warrantless, nonconsensual blood draw in every DWI investigation.