Updated at 5:24 p.m. ET
The double-jeopardy clause of the Constitution says a person can't be prosecuted twice for the same crime.
But, in fact, for 170 years, the Supreme Court has said that separate sovereigns — state and federal governments — can do just that, because each sovereign government has separate laws and interests.
On Thursday, the court heard arguments in a case that could reverse that long-standing rule. The case garnered lots of attention, because it could have consequences for special counsel Robert Mueller's investigation of President Trump and his associates' ties to Russia. The court even expanded the time for oral arguments by 20 minutes.
But, after arguments, the dual sovereigns rule looked to be safe for now. Only Justice Ruth Bader Ginsburg openly criticized what she called "the double whammy" of the dual sovereigns rule. At the same time, the argument produced an interesting debate among the justices about when it is appropriate to reverse a long line of decisions. (Hint: think Roe v. Wade or decisions on affirmative action in higher education.)
The dual sovereigns rule at issue in Thursday's case raised a red flag over the Mueller investigation, because if such double prosecutions were barred, some of those already convicted in the Mueller probe could not be tried for the same crimes in state court if Trump were to pardon them, something that he has openly flirted with doing.
Thursday's arguments, however, strongly suggested the court is unprepared to toss out the separate sovereigns rule. At least five of the nine justices, from liberal to conservative, expressed clear doubts about overruling nearly two centuries of precedent.
Representing the Alabama defendant, lawyer Louis Chaiten said the text of the Constitution and the original understanding of the Founders was that a person could not be tried twice for the same crime, even if the first prosecution was in a foreign country.
Justice Samuel Alito pounced. "Let's say a group of American tourists are murdered by terrorists in a foreign country," he said, and they are ineptly prosecuted in that country. Are you saying they could not be prosecuted afterwards "here in the United States?"
Justice Brett Kavanaugh suggested that in circumstances like this, a bar on a second prosecution would "substantially hamper ... the national security efforts of the United States."
Justice Elena Kagan extolled the importance of precedent, noting that the separate sovereigns rule has existed for 170 years and been approved of by at least 30 justices in the past. Respecting precedent is a "kind of doctrine of humility," she said, under which the courts resist overturning long-established rules "just because we think we can kind of do it better."
Justice Stephen Breyer seconded that thought, suggesting that if the court is prepared to overrule this precedent, why not Marbury v. Madison, which established judicial review of actions by the other branches of government?
"Look at the door we're opening up," he said.
Justice Neil Gorsuch followed up. "Of all the errors the court has made over the years," he asked, why reverse this one?
Defending the status quo was Assistant Solicitor General Eric Feigin, who said there would be dire practical consequences if the court were to do away with the separate sovereigns rule.
Gorsuch expressed concern over the "proliferation of federal crimes," which could allow the federal government to prosecute any time it is "unhappy with even the most routine state prosecution." In the past, he said, the court has relied on assurances that federal prosecutors wouldn't use the dual-sovereigns rule in routine cases, but this case, "at least to some eyes, looks pretty routine."
Feigin pointed to Department of Justice policy that allows such second prosecutions in a relatively small number of cases. He estimated there are about 100 per year. And he warned that getting rid of the rule could allow the state and federal governments to encroach on one another.
For example, he said that possession of 220 pounds of marijuana in California could be a misdemeanor; it's a felony under federal law. Similarly, an assault that state prosecutors pursue as a simple assault may be part of an organized crime case for federal authorities.
As to the weapons possession case before the court, he said, the federal government got involved because the defendant was given a very light jail term, even though he used the gun to repeatedly terrorize his family.
When do double prosecutions occur?
Double prosecutions most often come in high-profile cases, frequently civil rights cases, when there is a sense that justice has not been done.
In 1992, for instance, riots broke out in Los Angeles after a mostly white jury in the nearby suburb of Simi Valley acquitted four police officers in the videotaped beating of a black man named Rodney King.
The day after the state court verdict, Attorney General William Barr declared that "nothing in the state process is binding on us federally," and, indeed, several months later, federal prosecutors filed charges against the same police officers for violating King's civil rights.
A more racially mixed federal jury in Los Angeles subsequently convicted two of the officers.
What's the case before the Supreme Court?
The case the court is hearing Thursday is far more mundane than the King police brutality case. In 2015, seven years after Terance Gamble was convicted of robbery in Alabama, he was pulled over by police for a traffic violation.
When the cops found a handgun and two bags of marijuana in the car, the state charged him with violating an Alabama law barring felons from possessing a firearm.
Gamble pleaded guilty to the state charges and was sentenced to one year in prison, with the rest of his sentence suspended. His subsequent conviction for violating a nearly identical federal statute, however, added three years of prison time.
Gamble appealed the second conviction, contending it violated the U.S. Constitution's ban on double prosecution for the same crime. But the lower courts ruled that, under the Supreme Court's established precedents, the state and federal governments, as separate sovereigns, are allowed to bring such successive prosecutions.
A get-out-of-jail-free card for Trump associates?
The case has attracted extra attention because of Trump's comments that he could possibly pardon his onetime campaign chairman Paul Manafort and other Trump associates who have been — or could be — convicted in prosecutions brought by Mueller.
Presidential pardons, it should be noted, only apply to federal crimes. So, under current law, a state like New York, for example, could go after Manafort for the same crimes under state laws.
If the Supreme Court were to bar dual prosecutions, "there is a concern that a president of the United States could pardon an individual for all federal offenses" and it would effectively be a "pardon for everything," said George Washington University Law professor Stephen Saltzburg, who served as deputy assistant attorney general in the Reagan and Bush administrations.
These concerns, he noted, extend from the president down to governors or local prosecutors. They could "bestow great gifts upon friends or family by rushing to prosecute them for certain crimes," Saltzburg pointed out, by obtaining minimal punishments.
That would be "cutting off" the ability of the federal government to bring prosecutions, for the same conduct, particularly in corruption cases.
But Columbia Law School professor Daniel Richman, who previously headed the appeals section at the U.S. attorney's office in Manhattan, is not very worried about the Manafort case, or others like it.
Manafort, he said, is "sort of a one-man offense generator."
Put another way: If a prosecutor can't find different state crimes to charge someone like Manafort with, they should be in a different job.
Possible state charges could include money laundering or real estate fraud, according to Richman, who observes that every money laundering transaction is a separate crime, as is every false statement on a state form or state tax filing.
In a similar vein, Erwin Chemerinsky, dean of University of California, Berkeley School of Law, notes that the practical impact of a rule prohibiting separate sovereign prosecutions could be relatively minor, since federal and state crimes usually require proof of different elements.
Thus, for example, an acquittal on murder charges in state court may be followed by a federal prosecution for violating the victim's civil rights. And while the actual criminal act — killing — is the same, federal prosecutors may have to prove, for example, racial, ethnic or gender animus.
"What will be argued over and again is when are the elements sufficiently similar" that the second prosecution violates the Constitution's ban on double jeopardy, Chemerinsky said.
A low-level criminal with a high-stakes case
Gamble, the defendant at the center of Thursday's Supreme Court case, is the relatively rare defendant prosecuted by the state and federal governments for exactly the same crime but who is not involved in major criminal activity.
He was prosecuted on federal charges because the U.S. attorney in Alabama and the Obama administration were flagging felons with a history of domestic violence and violent gun use. Gamble had a history of terrorizing domestic partners with a gun.
Gamble's lawyers contend that, nonetheless, the double-jeopardy provision of the Constitution bars double prosecution and punishment for the same crime and that the nation's Founders never contemplated an exception that would allow the state and federal governments each a separate bite at the prosecution apple.
They argue it is time to overrule the separate sovereigns doctrine because it was wrong to begin with and because "the dramatic federalization of criminal law over the last 60 years" has "rendered almost laughable" the assumption that federal and state jurisdictions will only rarely overlap.
The federal government counters that the separate sovereigns doctrine dates back nearly two centuries and that it serves the distinct and separate interests of the state and federal governments.
In Washington, there are always rumors of hidden motives in a case like this. And, indeed, some in liberal circles have speculated that one reason the Trump administration was in such a hurry to get Kavanaugh confirmed to the Supreme Court was his demonstrated affinity for presidential power.
However, the Trump administration is urging the Supreme Court to preserve the status quo by upholding the separate sovereigns doctrine, as are 36 states, including states that lean "red" and "blue" politically.