Two years after President Obama signed the signature achievement of his administration, the Affordable Care Act, the Supreme Court heard arguments about whether a key provision of the law is constitutional.
In a courtroom stuffed with spectators, the justices focused intently on the individual mandate, the part of the law that requires most Americans to buy health insurance by 2014 or pay a penalty.
Read ABC's full coverage of the Supreme Court and Health Care Overhaul.
Solicitor General Donald B. Verrilli Jr., who seemed at times nervous and hoarse, arguing on behalf of the law, told the justices that the health care law was passed to address a "fundamental and enduring problem" in that millions of Americans were unable to get health care.
But the conservatives on the bench had some tough questions for the government lawyer.
Justice Anthony Kennedy got right to the core of argument. "Can you create commerce in order to regulate it?" he asked, referring to an argument from the challengers of the law who say that while Congress can regulate interstate commerce, it cannot force someone into the marketplace.
Chief Justice John Roberts and Justice Samuel Alito asked Verrilli about the limits of federal power.
"Can the government require you to buy a cellphone?" Roberts asked.
"Do you think there is a market for burial services?" Alito said.
Alito also asked the government: "Could you express your limiting principles as succinctly as possible?"
Kennedy suggested that the law which requires "the individual citizen" to act " is different from what we have in previous cases and that changes the relationship of the Federal Government to the individual in the very fundamental way."
Verrilli repeated that the law was not about forcing someone to buy a product, but regulating how it is paid for.
Justice Ruth Bader Ginsburg came to the government's side, pointing out that those people who choose not to buy health care affect the market place in a "major way" by shifting costs to those people who are insured, doctors and the insurance companies.
Paul D. Clement, arguing on behalf of 26 states challenging the law, said the individual mandate was "an unprecedented effort to compel an individual to enter into commerce" and said the law was "without any limiting principles."
But liberal Justices Sonia Sotomayor and Justice Elena Kagan seemed skeptical of Clement's argument that the government could have mandated individuals to buy insurance not in advance, but "at the point of consumption", at the hospital for example. Is this just a "matter of timing?" Kagan asked.
More than once, Roberts pointed out to lawyers challenging the law a key aspect of the government's argument: that health care is different than other markets because everyone will eventually find themselves, sometime in their lives, in need of health insurance. And Kennedy wondered about how a young person who is uninsured might affect the market.
Justice Kennedy, who is sometimes seen as the swing vote on the court, picked up on the government's argument that the health care market is unique. While he said he was concerned about the limits of that principle, he conceded that a young person who chose not to buy health care insurance could "be very close" to affecting the rates of insurance in a way that is not true in other industries.
"That's my concern" Kennedy said.