New York Times

WASHINGTON — For the fifth time since 2007, the Supreme Court on Monday struggled to make sense of a phrase in a federal law that requires longer sentences for some gun crimes based on earlier convictions.

“I can think of no other instance in which the court has endeavored so many times in so few years to answer precisely the same question,” said Katherine M. Menendez, a lawyer for a Minnesota man who was sentenced to 15 years in prison based in part on an earlier conviction for possessing a short-barreled shotgun.

The case, Johnson v. United States, No. 13-7120, was before the court for a rare re-argument. When the court first heard arguments in the case in November, the question before it was whether merely possessing the shotgun could be considered a violent felony under the law.

In January, the court asked the parties to come back for a second argument on the broader question of whether the key phrase in the law was unconstitutionally vague.

Under the law, convicted felons caught with guns face a maximum sentence of 10 years. But those with three prior convictions for violent felonies are subject to a 15-year mandatory minimum sentence.

Which crimes qualify as violent felonies has been the subject of much litigation. The law defines the relevant crimes to include burglary, arson, extortion, the use of explosives and ones that “otherwise involve conduct that presents a serious potential risk of physical injury to another.”

On Monday, Justice Samuel A. Alito Jr. suggested that the law, if not the court’s interpretations of it, was clear enough. “Can a statute be vague simply because this court messes it up?” he asked, adding that the court had twice upheld the constitutionality of the law.

The case concerned Samuel J. Johnson, a white supremacist from Minnesota who pleaded guilty to a gun charge. The trial judge ruled that he was subject to the mandatory minimum sentence because of earlier convictions for robbery, attempted robbery and possession of the shotgun.

Mr. Johnson argued that the third offense should not count under the law’s definition of violent felonies. The trial judge disagreed, imposing the 15-year mandatory sentence. But he was not happy to do so.

“For whatever it’s worth, and it’s probably worth nothing,” the judge said, “I think 180 months is too heavy of a sentence in this case. But I take an oath to follow the law as I see it, and I’ve made my decision in that regard.”

At Monday’s argument, Michael R. Dreeben, a lawyer for the federal government, said the law was a straightforward attempt to reduce recidivism. Mr. Johnson, he said, “knew or should have known that he could not possess a gun,” referring to the latest conviction.

Chief Justice John G. Roberts Jr. responded by returning to a theme that has troubled him in earlier cases involving harsh punishments.

“The problem is what the prosecutor threatens when he’s entered into plea bargain negotiations,” the chief justice said. “You are putting the defense counsel in a position where they have to interpret the vagueness in making the decision on whether they want to plead to five years or risk the mandatory minimum of 15.”

In 2011, the court ruled in Sykes v. United States, a 6-to-3 decision, that fleeing from the police in a car is a violent felony that can subject a defendant to the 15-year minimum sentence.

Justice Antonin Scalia’s dissent in the case foreshadowed Monday’s argument. He said that the law was a hopelessly vague congressional “drafting failure” and that the court’s “tutti-frutti opinion” had produced “a fourth ad hoc judgment that will sow further confusion.”