WASHINGTON – An unusual coalition of liberal and conservative Supreme Court justices appeared unlikely Thursday to block the federal and state governments from being able to prosecute suspects twice for the same crime.

What sounded on paper like a no-brainer ran into historical and practical concerns voiced by a majority of justices, who seemed inclined to retain the "dual sovereignty" exception to the Fifth Amendment's double jeopardy clause.

The unusually long 80-minute oral argument signified the importance of the case to both sides and showcased the unlikely alliances the issue engendered.

On one side: defenders of the Constitution's original meaning, such as Associate Justice Neil Gorsuch, and individual rights, led by Associate Justice Ruth Bader Ginsburg. To them, double jeopardy seems unjustified and unfair.

On the other side: those opposed to overruling the court's prior decisions except in extreme cases, such as Associate Justice Elena Kagan, or who worried that blocking second prosecutions could harm law enforcement, help criminals and even lock in faulty verdicts reached overseas, such as Associate Justice Samuel Alito.

By the end of the debate, it seemed the latter group held five or even six votes, enough to maintain the status quo in which separate state and federal prosecutions are permitted.

The court's newest justice, Brett Kavanaugh, said following Supreme Court precedent represented "a doctrine of stability and humility that we take very seriously." To overrule it, he said, challengers must show that the court's prior ruling was "grievously wrong."

The case is important as a matter of constitutional interpretation, but it has gained attention largely because of the possibility that President Donald Trump could pardon one or more of his former associates convicted in federal court by special counsel Robert Mueller as part of the investigation into Russian interference in the 2016 election.

If former Trump campaign chairman Paul Manafort or others were pardoned, they still could face state prosecutions for the same crimes under the court's precedents. That rule applies because state and federal governments are separate sovereigns.

Nevertheless, the Justice Department and a coalition of 36 states vehemently defended the status quo, which has led to successful second prosecutions after acquittals or hung juries.

For instance: It enabled Mississippi to convict Edgar Ray Killen of murdering three civil rights workers in 1964 after federal charges didn't stick. It helped the federal government convict two Los Angeles police officers for the notorious 1991 beating of Rodney King after a county jury acquitted four officers of nearly all charges. And it helped federal officials win a guilty plea last year from a South Carolina police officer for the 2015 shooting death of Walter Scott, an unarmed black man, after a state jury deadlocked.

If the court were to revert to a strict rule against double jeopardy, Associate Justice Stephen Breyer said, "look at the door we're opening up."

Ginsburg-Thomas coalition?

Going into the oral argument, it had appeared the court might be prepared to end federal-state dual sovereignty. Many legal analysts predicted the Constitution would come out on top.

Two years ago, the court ruled 6-2 that Puerto Rico could not prosecute a suspect after his federal conviction because the territory, unlike states, derived its power from the United States. The liberal Ginsburg and conservative Associate Justice Clarence Thomas went further, suggesting that the court consider a rigid application of the double jeopardy clause for all levels of government.

"Ordinarily, a final judgment in a criminal case, just as a final judgment in a civil case, should preclude renewal of the fray anyplace in the nation," Ginsburg wrote.

Gorsuch implied Wednesday that the court's prior approval of separate federal and state prosecutions was in error and asked why it should be preserved.

"It took until last year for this court to overrule Korematsu," Gorsuch noted, referring to a notorious decision upholding the internment of Japanese American citizens during World War II. That opinion actually was negated this past June in a separate case.

The case – delayed a day because of the national day of mourning for President George H.W. Bush – is one of the most significant on the court's thus-far underwhelming docket. A ruling against the federal and state governments would upend 170 years of history and high court precedents dating back nearly 60 years.

It would provide a victory for Terance Gamble, who received a one-year prison sentence from Alabama and 46 months from the federal government for the same firearms offense in 2015. Two lower courts upheld the sentences, citing Supreme Court precedent.

Although the terms are running concurrently, Gamble won't be released until 2020. Had the federal government been barred from a second prosecution, he would be a free man.

"The purpose of the double jeopardy clause," his lawyers argued in court papers, "is to protect against this most ancient and basic of evils."

Overturning convictions?

That view has plenty of proponents who argue that the double jeopardy clause prevents abuse by prosecutors. They say it helps in obtaining plea bargains because defendants cannot hope for a second trial.

What's more, nearly half the states already have bars against double jeopardy. That's important for Mueller's prosecution of Manafort, because the special counsel would have to cite different illegal conduct to bring state charges on top of federal charges.

The government's position, ironically, would help Mueller in the event of a Trump pardon. Clearing Manafort of federal tax charges would leave open the possibility of trying him on state tax charges.

In court papers, the federal and state governments cited the nation's federalist tradition, which empowers the states. If the justices were to block dual prosecutions, the Justice Department says, it could lead those convicted in the past to challenge "long-final convictions by whichever sovereign happened to go second."

A coalition of states led by Texas cited examples of cases in which the second prosecution succeeded after the first did not, such as the Rodney King beating.

"Those concerns are not limited to instances of racial bias," the states argued. "They could arise whenever there is the potential for jurors to be improperly influenced or swayed, as with prosecutions in cases of political corruption."

More:George H.W. Bush left both a liberal and conservative legacy at the Supreme Court

Related:Supreme Court to hear case on Trump administration plan to add citizenship question to 2020 Census

Also:Supreme Court's latest church-state conundrum: Must a 'peace cross' memorial to World War I vets come down?