A number of states, like Arizona, allow the police to do a blood draw in some
DUI cases without a warrant. In other words, the cops don't even have to ask
a judge. They can just take you to the hospital or mobile lab and get
your blood drawn, probably while you're still in handcuffs.
But this might come to an end (or happen less often) because the U.S. Supreme
Court has ruled that law enforcement needs a warrant before taking your
blood. Bill Mears with CNN reports that the Court found in favor of people
accused of DUI. The cops must first get a warrant; otherwise, it would
be an unreasonable search and seizure.
Mears quotes Justice Sonia Sotomayor's opinion in that DUI investigations
don't always require the immediate testing of blood without a warrant.
In other words, the cops can't say they needed to draw blood first
for fear that a DUI suspect's blood alcohol content would decrease
in the time it would take to get a warrant. But the warrantless blood
draw will likely continue, which would occur in
felony DUI cases, where someone was injured or killed.
Supreme Court rules against police in drunk driving case