– A testy U.S. Supreme Court pressed a Dakota County attorney Wednesday to defend why suspected drunken drivers should be criminally punished for refusing a blood-alcohol test.

The court is looking to settle hotly debated implied-consent laws in Minnesota and 12 other states, laws that have endured countless lower court challenges from those arguing that the tests are unconstitutional without a search warrant.

The case has massive implications nationwide in how states treat thousands of drivers each year who refuse to consent to a blood-alcohol test. Advocates say the ability to criminally punish a motorist for refusing to take the test is critical in keeping drunken drivers off the road. With the Supreme Court accepting the cases out of Minnesota and North Dakota, it appears the justices want to clear up the Fourth Amendment argument against unreasonable searches.

During more than 60 minutes of back and forth in oral arguments, the justices appeared skeptical.

They made sharp distinctions between the invasiveness of a breath test vs. a blood test and questioned whether driving a car waived certain constitutional protections by default to protect others — similar to going through a metal detector in a government building and permitting an officer to pat you down if there was suspicion you were carrying a weapon.

The case stemmed from an incident involving William Bernard of Eagan. In 2012, Bernard was charged with two felony counts after he refused a Breathalyzer. He was arrested after officers approached him at a public boat ramp and asked him to submit to field sobriety tests. In Bernard’s case, as with the two cases out of North Dakota, the state’s supreme courts ruled against the drivers.

Charles Rothfeld, a Washington, D.C.-based attorney who represented Bernard and two other men from North Dakota, argued that Minnesota’s existing law is at fundamental odds with protections against unreasonable search and seizure.

“On this basis … where is the right to drive in the Constitution?” Chief Justice John Roberts asked Rothfeld.

Justice Stephen Breyer pushed Rothfeld on the actual invasiveness of a breath test, arguing that people exhale air that is going out in the atmosphere anyway. He asked what was wrong with taking a breath test when it could save “lots of lives” if it dissuaded some people from drunken driving.

Rothfeld called a breath test “a significant intrusion on personal liberty” — a sentence interrupted by Justice Elena Kagan, who said, “this is about as uninvasive as a test can be!”

Justices saved some of the toughest questions for attorneys representing the states.

Justice Sonia Sotomayor pressed both the North Dakota and Minnesota attorneys on their assertion it could be a burden to get a warrant every time they wanted to do a breath or blood test — particularly if most tests, even Breathalyzers, are conducted in police stations.

Kathryn Keena, an assistant Dakota County attorney, told the court it is a huge burden, especially for rural counties, to require a warrant in every single potential investigation of drunken driving. Some attorneys estimate that authorities administer 20,000 breath tests each year in Minnesota.

Keena said that in a lot of jurisdictions there is only one officer on duty at a time, and a judge home asleep, which can make warrants an extra burden.

Sotomayor told Keena that Minnesota was asking the Supreme Court to waive a constitutional protection just to make it easier for states to prosecute suspected drunken drivers, which is not the high court’s role. “It’s as if you want to create an exception to the Fourth Amendment … in a drastic way,” Sotomayor said.

Then, in a lighter moment, Breyer quipped to Keena, “Justice Sotomayor is assuming you’re going to lose and she would like your reaction!”

The courtroom laughed and Keena sat down.

Afterward, Keena said she felt hopeful about the direction of the court’s arguments.

It seemed the justices were eventually going to grant that breath tests could be taken without a warrant — and allowed to be attached to a criminal penalty for saying no — but they might reject that blood or urine samples be treated equally, she said.

Keena said that would make it harder to prosecute driving-while-on-drugs cases, however.

“We’re finding in some situations that a lot of these arrests are occurring at times that judges are sleeping and it’s really difficult to try and get a search warrant,” she said. “The judges talk about getting warrants in 15 minutes and that’s not the case yet in Minnesota.”

On the other side, Jeffrey Sheridan, a Minnesota attorney who represented Bernard in front of the state’s Supreme Court, said he, too, was hopeful.

He doesn’t think the court will draw a distinction between a breath test and a more invasive blood or urine test.

“At the end of the day it’s not the nature of the intrusion, but the purpose of the intrusion,” Sheridan said outside the court Wednesday.

“The court clearly indicated in their exchange with government lawyers that it’s not that big of a deal to just go get a warrant,” he said. “If you’re too disinterested in that, and you just prosecute the guy, I don’t see the court as being willing to go down that path.”

The high court’s final ruling is expected in the next two months.