Police watch as doctors and other medical professionals stand outside the US Supreme Court

CNN

In one of the most anticipated Supreme Court hearings in years, the justices on Tuesday offered sharply divided views on the controversial individual mandate provision at the heart of the 2010 federal health care reform law.

The fate of the individual mandate -- requiring most Americans to purchase health insurance by 2014 or face a financial penalty -- may be in jeopardy, and perhaps with it the entire law's other 450 or so sections, based on tough questions of the government by the court's conservative majority, reports CNN.

Jeffrey Toobin, CNN's senior legal analyst, said questions asked at oral arguments often show how justices are thinking, and based on what he heard Tuesday, the health care reform law could be in "grave danger."

Neither the justices nor the lawyers arguing before them mentioned "Obamacare"-- as opponents have labelled the law pushed through Congress by Democrats and President Barack Obama -- or the president by name.

But the court seemed fully aware of the landmark consequences of their eventual rulings.

"Those who don't participate in health care make it more expensive for everyone else," said Justice Ruth Bader Ginsburg, in support of the law. "It is not your free choice" to stay out of the market for life, she said.

Hear Tuesday's oral arguments

Younger, mostly healthy people who would be the "subsidizers will become the subsidized" when they grow older, added Justice Elena Kagan.

However, Justice Anthony Kennedy said that the federal government "is telling an individual he has the obligation he must act" and purchase insurance.

"That threatens to change the relationship between the government and the individual in a profound way," Kennedy said.

If Congress could regulate health care in the name of commerce, added Chief Justice John Roberts, "all bets are off" on a range of areas subject to federal oversight.

Tuesday's argument was the biggest of the high court's three-day marathon this week examining the limits of congressional authority. It was part legal seminar, part history lesson, with politics sprinkled throughout.

At least 17 members of Congress attended, along with several members of the Obama administration, including Attorney General Eric Holder.

Administration officials, speaking on condition of not being identified, said they expect the high court to uphold the individual mandate despite the tough questioning Tuesday.

They noted conservative judges who asked similarly challenging questions as the issue made its way to the Supreme Court ended up upholding the mandate, and that Roberts targeted both sides with his queries.

Outside the court, duelling news conferences and protests Tuesday reflected the partisan nature of the health care debate.

Rep. Michele Bachmann of Minnesota, who failed in her bid for the Republican presidential nomination to take on Obama in November, told tea party supporters near the Supreme Court building that the issue is freedom for individuals to decide their health care needs.

"If the federal government can tell you, when you are not doing anything, that you must do something, then the federal government can tell you anything," Bachmann said, later adding a call for the Supreme Court to declare the mandate unconstitutional.