Missouri v. McNeely
The Supreme Court ruled that police cannot automatically skip getting a warrant for a blood test just because a drunk-driving suspect's blood alcohol level is naturally dropping over time. Instead, officers must show that a warrant genuinely could not have been obtained in time under the specific circumstances of each case.
The decision rejects a blanket rule sought by Missouri and instead keeps in place a case-by-case approach, meaning police and courts will keep weighing factors like how quickly warrants can be obtained locally before deciding whether a warrantless blood draw was justified.
“exigency in this context must be determined case by case based on the totality of the circumstances.”
The Court's core holding rejecting a blanket rule for warrantless blood draws in drunk-driving cases.
How it got here: A Missouri trial court suppressed the blood test result, the Missouri Supreme Court affirmed, and the State asked the U.S. Supreme Court to adopt a categorical rule allowing warrantless blood draws.
The Case in Depth
What happened
A Missouri police officer stopped Tyler McNeely for speeding and swerving, suspected he was drunk, and arrested him after he refused a breath test. The officer took McNeely to a hospital and, without ever trying to get a warrant, directed a technician to draw his blood over his objection. The test showed McNeely's blood alcohol was well above the legal limit, and he was charged with driving while intoxicated.
The question before the Court
If a driver's blood alcohol is naturally dissipating, can police always draw his blood without a warrant?
Why it matters
Police departments across the country cannot treat every drunk-driving stop as an automatic excuse to skip a warrant before drawing blood. Officers will need to assess, case by case, whether they realistically had time to get a warrant, which pushes departments to build faster, more reliable warrant procedures like phone or electronic applications for late-night arrests.
What changes now
The Missouri Supreme Court's judgment suppressing the blood test is affirmed, meaning that evidence cannot be used against McNeely in his case. More broadly, police and lower courts must now evaluate warrantless blood draws in drunk-driving stops individually, weighing factors like local warrant-processing speed, rather than relying on an automatic rule. Future cases will keep testing how this case-by-case standard applies to specific facts the Court did not resolve here.
What this does not decide
The Court did not decide whether an emergency actually existed in McNeely's specific stop, because Missouri only argued for a blanket rule and never separately claimed the facts of this case showed a true emergency. It also left open exactly which combinations of facts will justify a warrantless blood draw in future cases.
Concurrences and dissents
Concurrence — Justice Kennedy
Justice Kennedy joined the core majority parts affirming that a blanket warrant exception is impermissible, but he stressed that this case does not foreclose states from adopting clear rules and protocols to guide officers, and that the Court may need to provide more detailed guidance in a future case with a better factual record.
Dissent in part — Justice Roberts
Chief Justice Roberts agreed that a blanket rule treating alcohol dissipation as always exigent is too broad, but argued the Court should have given police clearer guidance: if there is time to get a warrant before blood can be drawn, officers must seek one; if not, they may proceed without one. He would have vacated and sent the case back for the Missouri courts to apply that more specific rule.
Dissent — Justice Thomas
“As a result, I would hold that a warrantless blood draw does not violate the Fourth Amendment.”Thomas's view that alcohol's natural dissipation always creates an emergency justifying a warrantless blood draw.
Justice Thomas argued that because alcohol is constantly and inevitably being eliminated from the bloodstream, this destruction of evidence itself always creates an exigency, regardless of how much time a warrant might take. He would have held that warrantless blood draws are always permissible once police have probable cause to believe a suspect is driving drunk, criticizing the majority's case-by-case test as unworkable for officers in the field.
How the Court got there
The legal reasoning, step by step
- The Court started from the general Fourth Amendment rule that a warrantless search of a person is reasonable only if it fits a recognized exception, and identified the exigent-circumstances exception -- allowing warrantless action when an emergency makes getting a warrant impractical -- as the one at issue here.
- The Court read its earlier decision in Schmerber v. California, which allowed a warrantless blood draw from a drunk-driving suspect, as resting on the totality of the specific facts in that case (an accident, time spent investigating the scene, and transporting an injured suspect), not on a blanket rule that alcohol dissipation alone is always an emergency.
- The Court rejected Missouri's proposed per se rule that probable cause for drunk driving automatically creates an exigency, reasoning that because blood alcohol declines gradually and predictably, and because some delay before testing is inevitable anyway (getting to a hospital, finding medical staff), there is usually still room for police to seek a warrant.
- The Court noted that modern tools like telephonic and electronic warrant applications, adopted in many states, make it easier than in 1966 for officers to get a warrant quickly, undercutting the claim that warrants are always too slow to matter.
- Applying this case-by-case approach, the Court found that Missouri had argued only for the categorical rule and never separately argued that the specific facts of McNeely's stop created an emergency, so it had nothing further to weigh in his favor.
Doctrinal impact
Cases affected by this decision
Reaffirms Schmerber v. California (384 U. S. 757)
The Court treated Schmerber's warrantless blood draw as justified by its own specific facts, not as creating an automatic rule.