WASHINGTON — Three days after the fierce battle over his nomination ended in his elevation to the Supreme Court, Justice Brett M. Kavanaugh joined his new colleagues on the bench for the first time on Tuesday morning, taking a seat on the far right side of the bench, in the spot reserved for the most junior justice.
The rancor that had consumed the Capitol, just across the street, ahead of his confirmation vote last week had dulled to a polite hush as spectators gathered in the courtroom midmorning. The arguments concluded without any protests, a contrast with the outbursts that disrupted Justice Kavanaugh’s testimony about sexual assault allegations against him and the Senate vote on his elevation to the Supreme Court.
Shortly before the arguments began, Justice Kavanaugh’s wife, Ashley Kavanaugh, entered and sat on the south side of the room, closest to his new seat. His daughters sat at her side, gazing at the elaborate marble frieze near the ceiling. Minutes later, Justice Anthony M. Kennedy, whose seat on the court was filled by Justice Kavanaugh and for whom Justice Kavanaugh once served as a law clerk, entered and sat just feet from the new justice’s seat.
A court officer then gave unusually stern and detailed instructions to the audience. “It is critical that you remain seated and silent,” he said.
Chief Justice John G. Roberts Jr. started the day by welcoming his new colleague. “Justice Kavanaugh,” the chief justice said, “we wish you a long and happy career in our common calling.”
Justice Elena Kagan, who sits next to Justice Kavanaugh on the bench, whispered and laughed with him in the moments before the argument began. Justice Neil M. Gorsuch, President Trump’s first appointee to the Supreme Court, took his new seat at the opposite end of the bench, next to Justice Sonia Sotomayor.
The court heard two hours of arguments in three cases, all concerning a complicated and ambiguous federal law that has long vexed the justices. The cases did not raise questions of high constitutional moment or involve deeply contested social issues, which may be just as well for a court that has sustained collateral damage from a confirmation fight marked by bitterness, distrust and raw partisanship.
The arguments had a notably light tone. Several justices asked whether pinching amounts to violence, and Justice Sotomayor appeared to pinch Justice Gorsuch. A lawyer for a criminal defendant said that pinching Arnold Schwarzenegger might not amount to violence if he was “uniquely immune to pain.”
Chief Justice Roberts asked how hard it is to wrest a dollar bill from a clenched fist and said he had experimented with his law clerks. “It requires a lot of force,” he said, “more than you might think.”
The arguments were interrupted by laughter more than a dozen times.
Justice Kavanaugh took a more serious approach, often asking how particular precedents applied to the cases before the court.
At one point, he asked a lawyer for the federal government how consequential a ruling against his position would be. “How many states are affected?” he asked.
The law under consideration in Tuesday’s arguments, the Armed Career Criminal Act, is a kind of three-strikes statute. It requires stiffer sentences for people convicted of possessing firearms in federal court if they have earlier been found guilty of three violent felonies or serious drug charges.
Figuring out what qualifies as one of those earlier offenses is not always easy. The first case, Stokeling v. United States, No. 17-5554, concerned a part of the law that defined violent felonies to include any offenses involving the use or threat of physical force. The question in the case is whether minimal force, as in a purse snatching, is enough.
The case involves Denard Stokeling, who pleaded guilty to possessing a gun after burglarizing a restaurant in Miami Beach. He had three earlier convictions, and prosecutors argued that they required a much longer sentence than the one the gun charge would ordinarily have warranted.
Mr. Stokeling objected, saying his 1997 conviction for “unarmed robbery” in state court, arising from a snatched necklace, did not amount to a violent felony. That meant, he said, that he should face only a maximum sentence of 10 years rather than a minimum sentence of 15 years.
The court also considered another part of the same law in two other cases — United States v. Stitt, No. 17-765, and United States v. Sims, No. 17-766 — consolidated for a single hour of arguments.
The law says burglaries are violent felonies that can require longer sentences. But it does not specify what qualifies as a burglary.
The Supreme Court has said the crime requires invasion of “a building or structure.” But the defendants in the two cases — Victor Stitt of Tennessee and Jason Sims of Arkansas — were convicted under state laws that allow prosecutions of burglaries of mobile homes and other vehicles in which people sleep.
Justice Samuel A. Alito Jr. expressed frustration with the court’s interpretations of the firearms law generally. “In my humble opinion, in this area, we have made one royal mess,” he said. “Maybe we ought to go back and correct our own mess.”
But Justice Kavanaugh said the law worked well enough in the typical case, as when someone is caught repeatedly breaking into recreation vehicles.
“I think if you’re convicted three separate times of breaking into an R.V.,” he said, “you would be on some notice that you shouldn’t be possessing a firearm under federal law.”
Hours before Tuesday’s arguments were to begin, the scene in front of the court had quieted dramatically from the protests in the same spot in the days after Justice Kavanaugh was confirmed.
Diane Young, an undergraduate at Georgetown University who attended Justice Kavanaugh’s confirmation hearings, waited in line near a man in a National Rifle Association baseball cap with a copy of a biography of Justice Anthony M. Kennedy. Unsettled by Justice Kavanaugh’s testimony in front of the Senate Judiciary Committee, she wanted to see his first day on the bench to know if anything would be different.
“I wanted to see how Justice Kavanaugh would conduct himself on the bench on his first day,” she said. “I’m very interested in how the Supreme Court adjusts its image in the public eye.”