The driver is unconscious at the hospital. No breath test is possible, and no one can consent. Mitchell v. Wisconsin covers this — with a caveat worth knowing.
What did Mitchell v. Wisconsin decide?
When a driver is unconscious and therefore cannot be given a breath test, the exigent-circumstances doctrine will almost always permit a blood test without a warrant. The Court decided this as a plurality and remanded to give the defendant a chance to show the unusual case — where police had time to get a warrant and no other pressing duties.
Mitchell v. Wisconsin, 588 U.S. 840 (2019) — read the opinion on CourtListener.
What does Mitchell allow?
- A warrantless draw in the ordinary unconscious-driver case, where breath testing is impossible and officers have competing duties
- Relying on the exigency created by the combination of an unconscious suspect, a medical setting, and time-limited evidence
What does it NOT allow?
- Reading this as a bright-line rule — it’s a plurality, and the defendant may still show police had time and no pressing duties
- Extending it to a conscious driver who refuses, which is McNeely and Birchfield territory
- Ignoring your state’s implied-consent statute and case law, several of which are stricter than this floor
How it plays out on the street
Treat Mitchell as strong cover, not a blank check. If a warrant is genuinely easy to get and you’re not doing anything else, get it — that is precisely the scenario the Court left open. Document the competing duties honestly: the crash scene, the transport, the other units tied up. Note also that this is a plurality opinion with real state variation underneath it, and several state supreme courts have gone their own way on unconscious-driver draws, so check yours before you rely on Mitchell alone.
Frequently asked questions
Can police draw blood from an unconscious DUI suspect without a warrant?
Almost always yes under Mitchell, because breath testing is impossible and exigency will typically be present — but it isn't an absolute rule.
Is Mitchell a bright-line rule?
No. It's a plurality opinion, and it leaves room for a defendant to show that police had time to get a warrant and no other pressing duties.
Related cases
- Missouri v. McNeely (2013): Is Alcohol Burning Off an Automatic Exigency?
- Birchfield v. North Dakota (2016): Breath Test vs. Blood Test on a DUI Arrest
- NJ DWI Laws: A Patrol Officer’s Complete Field Reference
Carry the rule, not the guesswork. Every case in StreetSense is broken down like this — bottom line, limits, and the exact citation — verified against the real opinion and available fully offline on shift. Start the free trial.
StreetSense is an educational reference for law enforcement, not legal advice. Federal cases set the floor — your state constitution, statutes, and department policy can impose stricter limits. Always follow your state’s rule and your agency’s policy.
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