(CBS News) WASHINGTON - In the fight over President Obama's health care law, this was the main event. On Tuesday, the nine justices of the Supreme Court heard arguments on the part of the law that requires all Americans to have health insurance or pay a fine. It's called the individual mandate. The Obama administration said that the mandate will make sure everyone has health care while keeping insurance affordable. Opponents say it's a dangerous new power for the government by forcing citizens to buy a product.
In a rare move, the court is releasing audio tapes of the arguments. CBS News correspondent Jan Crawford reports on the justices' views.
The health care law is considered President Obama's signature achievement, but Tuesday it appeared a majority of the justices were ready to describe the individual mandate another way: unconstitutional. The conservative justices--and that key swing justice, Anthony Kennedy --expressed serious doubts about the law.
Justice Kennedy, who often provides the decisive fifth vote, appeared troubled that Congress for the first time was ordering Americas to buy a product like insurance.
"That is different from what we have in previous cases. That changes the relationship of the federal government to the individual in a very fundamental way," he said.
That's the issue at the heart of the case: the federal government's power in people's lives. The Constitution gives Congress specific, limited powers -- one being the authority to "regulate Commerce."
Opponents argue that doesn't give Congress the power to create commerce by forcing people to buy healthcare.Supporters say uninsured people already are consumers of healthcare who just leave hospitals and taxpayers stuck with their bills.
The conservative justices and Kennedy, a moderate, expressed concerns the law gave Congress broad new powers to dictate behavior.
Chief Justice Roberts asked if Congress could force people to buy insurance -- since everyone will need it someday -- could it also require them to buy cell phones to call 911 when they eventually needed emergency assistance.
"You don't know if you're going to need police assistance," said Roberts. "You can't predict the extent to emergency response that you'll need. But when you do and the government provides it."
Roberts also seemed troubled that if the Court upheld the law requiring Americans to buy insurance, what would Congress try next.
"And we can compel people to do things -- purchase insurance in this case, something else in the next case," he said.
Justice Scalia offered one idea. "Can I tell you what the something else is while you're answering it?" he asked. "The something else is everybody has to exercise, because there's no doubt that lack of exercise causes illness, and that causes health care costs to go up. "
All four of the court's liberal justices defended the law. In one exchange, Justice Ruth Bader Ginsburg tossed a friendly question to the administration's top lawyer, Solicitor General Donald Verrilli.
"I thought a major, major point of your argument was that the people who don't participate in this market are making it much more expensive for the people who do," she said.
There was a lot of talk outside the courtroom after the argument that Verrilli, the administration's lawyer, really struggled under these tough questions. In these kind of complex cases, the justices always hammer the lawyer. These questions go back and forth, rapid fire, just like we saw today, just like Verrilli. As many of the questions proved, it was not the easy ride defenders of the law had been confidently predicting.
"Evening News" anchor Scott Pelley pointed out to Crawford that she had warned earlier not to draw too many conclusions from the questions that the justices asked.
"That's exactly right," she said. "I think if we had to guess today what the justices would decide, they would strike down this individual mandate. But think about what happens next. They go into their conferences, they discuss this case among themselves. Then they start writing their opinions and sometimes they change their minds. If you look back over history over the last 20 years, one of the justices who's often changing his mind is Justice Kennedy."