WASHINGTON — With the fate of President Obama’s health care law hanging in the balance, a lawyer for the administration faced a barrage of skeptical questions on Tuesday from four of the Supreme Court’s more conservative justices, suggesting that a 5-to-4 decision to strike down the law was a live possibility.
Predicting the result in any Supreme Court case, much less one that will define the legacies of a president and a chief justice, is nothing like a science, and the case could still turn in various directions. But the available evidence indicated that the heart of the Affordable Care Act is in peril.
The court’s decision is expected by June, and much may change as the justices deliberate and exchange draft opinions in the coming months.
If the indications from Tuesday’s arguments are correct, though, the ruling may undo parts or all of the overhaul of the health insurance system, deal Mr. Obama a political blow in the midst of the presidential election season, and revise the constitutional relationship between the federal government and the states.
The tone on Tuesday made a question to be addressed in the third and final day of arguments on Wednesday all the more important: If the individual mandate requiring most Americans to obtain health insurance or pay a penalty fell, what other parts of the law would fall along with it?
On Tuesday, Justice Anthony M. Kennedy, the court’s swing justice, asked a host of questions indicating discomfort with the law.
“Can you create commerce in order to regulate it?” Justice Kennedy asked the administration’s lawyer, Solicitor General Donald B. Verrilli Jr., only minutes into the argument. He later told Mr. Verrilli that the federal government faced “a heavy burden of justification” and pressed him to articulate “some limits on the commerce clause” of the Constitution.
“You are,” Justice Kennedy said, “changing the relationship of the individual to the government.”
Justice Kennedy’s questioning is often hard to read, and near the end of the argument he noted that “most questions in life are matters of degree.” But his questioning was, on balance, skeptical.
Justices Antonin Scalia and Samuel A. Alito Jr. were consistently hostile to the law. Chief Justice John G. Roberts Jr.was a little less so.
The conventional view is that the administration will need one of those four votes to win, and it was not clear that it had captured one.
The court’s four more liberal members — Justices Ruth Bader Ginsburg, Stephen G. Breyer, Sonia Sotomayor and Elena Kagan — indicated that they supported the law, as expected. Justice Clarence Thomas, who asked no questions, is thought likely to vote to strike down the law.
Everything about Tuesday’s argument was outsize. It was, at two hours, twice the usual length. The questioning was, even for the garrulous current court, unusually intense and pointed. And the atmosphere in the courtroom, which is generally subdued, was electric.
Mr. Verrilli seemed taken aback by the hostile reception from the court’s conservatives. He got off to a rocky start and never seemed to quite find his footing during his hour at the Supreme Court lectern.
Paul D. Clement, representing the 26 states challenging the law, and Michael A. Carvin, representing private challengers, were more assured, perhaps encouraged by the first part of the argument. Mr. Clement is a particularly fluid and conversational advocate, and he seemed eager to parry questions from the court’s liberal wing.
Wednesday’s argument about the other elements of the law may provide further clues about the fate of the mandate. It is one thing, after all, to ask questions about a hypothetical ruling striking down the mandate and another to seek practical advice about the consequences of such a decision.
The central legal question for the justices on Tuesday was whether Congress had exceeded its constitutional authority to regulate interstate commerce in enacting the insurance mandate.
Mr. Verrilli argued that the law was a valid response to a crisis in the market for health care. The individual mandate, he said, merely regulates how people pay for services they are virtually certain to use at some point in their lives and is well within the authority granted to the federal government by the Constitution.
Justice Ginsburg seemed to agree, saying the mandate was a response to the fact that uninsured people receive free health care that ends up being paid for by others. “The problem is that they are making the rest of us pay,” she said.
Justice Sotomayor said Americans would not stand for a system in which children in danger of dying were turned away from emergency rooms.
But several of the more conservative justices seemed unpersuaded that a ruling to uphold the law could be a limited one. Justice Alito said the market for burial services had features similar to the one for health care. Chief Justice Roberts asked why the government could not require people to buy cellphones to use to call emergency service providers.
Justice Scalia discussed the universal need to eat.
“Everybody has to buy food sooner or later, so you define the market as food,” he said. “Therefore, everybody is in the market. Therefore, you can make people buy broccoli.”
Justice Alito asked Mr. Verrilli to “express your limiting principle as succinctly as you possibly can.”
Instead of a brisk summary of why a ruling upholding law would not have intolerably broad consequences, Mr. Verrilli gave a convoluted answer. First of all, he said, Congress has the authority to enact a comprehensive response to a national economic crisis, and the mandate should be sustained as part of that response.
He added: “Congress can regulate the method of payment by imposing an insurance requirement in advance of the time in which the service is consumed when the class to which that requirement applies either is or virtually most certain to be in that market when the timing of one’s entry into that market and what you will need when you enter that market is uncertain and when you will get the care in that market, whether you can afford to pay for it or not and shift costs to other market participants.”
The Supreme Court has read the commerce clause broadly, saying it allows Congress to limit how much wheat may be grown on a family farm and to punish the cultivation of homegrown marijuana.
There have been only two modern exceptions to that broad interpretation. In 1995, the court struck down a federal law regulating guns near schools. In 2000, it struck down a federal law allowing suits over violence against women. In both cases, the court said the activity sought to be regulated was local and noncommercial.
Justice Breyer said those precedents and others demonstrated that Congress was free to address problems in the delivery of health care.
“I look back into history,” he said, “and I see it seems pretty clear that if there are substantial effects on interstate commerce, Congress can act.” An example, he said, was “the national bank, which was created out of nothing to create other commerce out of nothing.”
Mr. Clement, representing the 26 states in the case, Department of Health and Human Services v. Florida, No. 11-398, said it was one thing to establish a bank and another “to force the citizenry to put all of their money in the bank.” The second sort of law, he suggested, would be analogous to the individual mandate.
Justice Breyer asked whether people entered the health care market simply by being born.
Mr. Carvin, the lawyer for the private challengers, said that “if being born is entering the market,” then “that literally means they can regulate every human activity from cradle to grave.”