The U.S. Supreme Court Wednesday limited the power of police officers to take blood samples from suspected drunken drivers without getting a search warrant.

The 5-4 decision in a Missouri case could jeopardize current practices in Minnesota, where state law makes it a crime to refuse a blood alcohol test. Police here also take blood samples without a court order in cases involving serious injury or death.

A pair of recent rulings by the Minnesota Supreme Court said that was permissible because of the risk that blood alcohol levels could dissipate in the time required to obtain a warrant, but the majority in Wednesday’s federal decision rejected the idea that the fear of delay justified going ahead without a warrant in all cases.

“Consider, for example, a situation in which the warrant process will not significantly increase the delay before the blood test is conducted because an officer can take steps to secure a warrant while the suspect is being transported to a medical facility by another officer.” Justice Sonia Sotomayor wrote in the majority opinion in Missouri v. McNeely. “In such a circumstance, there would be no plausible justification for an exception to the warrant requirement.”

She also wrote, however, “cases will arise when anticipated delays in obtaining a warrant will justify a blood test without judicial authorization.”

Minnesota police and prosecutors don’t need to make any immediate changes, according to an e-mail from the Minnesota County Attorneys Association (MCAA) to its members.

“Unfortunately, Justice Sotomayor’s decision does not give a lot of guidance to law enforcement in terms of when they need to get a warrant,” wrote Traffic Safety Resource Prosecutor Bill Lemons. “Most importantly, it doesn’t give any guidance of how much delay is too much delay,”

Noting that the Missouri case did not involve a crash, he advised arresting officers to continue current practices, including warning drivers that under Minnesota’s implied consent they can be charged with a crime if they refuse a blood test.

That warning, however amounts to coercing suspected drunken drivers into giving blood and violates their rights to have a judge rule on the issue, according to some Minnesota defense attorneys.

Under the McNeely decision, “It’s now unconstitutional to threaten a driver with criminal charges in order to obtain their consent,” said DWI defense attorney Charles Ramsay.

“Even today there are thousands of DWI cases that are pending,” he said. “I believe that in almost every single one of those cases the alcohol test should be thrown out.”

Criminal defense attorney Ryan Garry said the ruling stretches far beyond drunken driving cases.

“What I do think is that this case is a victory for anyone that believes in the constitutional protections of the individual,” he said. “The Supreme Court ruling that the Fourth Amendment applies to your body just as it does to your home is important for everyone — not just defense lawyers representing people in DWI cases.”

In earlier cases, Minnesota vs. Netland, which involved a blood test refusal, and Minnesota vs. Shriner, which involved a forced blood test, the Minnesota Supreme Court held that the delays required in obtaining a search warrant while blood alcohol levels quickly drop, jeopardizing the evidence, justify warrantless searches under a “single factor exigent circumstance.”

The U.S. Supreme Court decision, however, reasoned that warrantless blood draws should be decided on a case-by-case basis based on the “totality of circumstances,” rather than solely on the fact that the body metabolizes alcohol quickly.

The majority held that because it has become much easier to quickly obtain a warrant, such as by telephone or e-mail, police officers must abide by the Fourth Amendment in DWI cases — just as in other criminal cases.

“It’s complicated and yet it isn’t, but this thing will play out for years. What impact it might have on implied consent, who knows,” MCAA executive director John Kingrey said. “We’re advising our members to continue our current practice. At this point we’re not saying the sky is falling.”