WASHINGTON (AP) — The Supreme Court is considering whether police must get a warrant before ordering a blood test on an unwilling drunken-driving suspect.

The justices heard arguments Wednesday in a case involving a disputed blood test from Missouri. Police stopped a speeding, swerving car and the driver, who had two previous drunken-driving convictions, refused to submit to a breath test to measure the alcohol level in his body.

The justices appeared to struggle with whether the dissipation of alcohol in the blood over time is reason enough for police to call for a blood test without first getting a warrant.

In siding with defendant Tyler McNeely, the Missouri Supreme Court said police need a warrant to take a suspect's blood except when a delay could threaten a life or destroy potential evidence.

The state court upheld an order throwing out the results of the blood test, which showed that McNeely's blood-alcohol content was .154 percent, well above the .08 percent legal limit.

Lawyers for Missouri and the Obama administration urged the justices to reject the state court decision and allow police to forgo a time-consuming process. In 2010, the administration said, more than 10,000 people died in crashes involving alcohol-impaired drivers, an average of one death every 51 minutes.

"Here, police are facing the certain destruction of blood-alcohol evidence," Justice Department lawyer Nicole Saharsky said.

But several justices suggested that law enforcement officers should at least usually try to obtain a warrant. "Why shouldn't the determination be made case to case?" Justice Antonin Scalia asked.

All 50 states have laws requiring drivers who are arrested on suspicion of driving while drunk to consent to a blood alcohol test, and refusal to submit to the test generally leads to suspension of a driver license. In addition, prosecutors can use the refusal against a defendant at trial.

In Missouri, a driver who won't agree to either a breath or blood test can have his license suspended for a year. The American Civil Liberties Union, representing McNeely, said that the suspension is only 30 days for drivers with no previous convictions who take the test and are found to be impaired.

But McNeely may have had more reason than most to object to taking the test. Missouri said McNeely faced a felony charge with a maximum prison term of four years because of his two prior convictions.

He failed several field sobriety tests and the arresting officer, Cpl. Mark Winder of the Missouri State Highway Patrol, said McNeely's speech was slurred and he was unsteady on his feet.

There seemed little dispute that Winder had enough evidence to get a warrant for a blood test, but chose not to. Instead, he drove McNeely to a hospital. A technician drew blood from McNeely, who was handcuffed throughout the process. Winder's decision set in motion the Supreme Court case.

A decision is expected by summer.

The case is Missouri v. McNeely, 11-1425.