The Obama administration forcefully defended the constitutionality of the individual mandate on Friday, the key provision of the health care law that requires individuals to buy health insurance by 2014 or pay a tax penalty.

In a 62-page filing with the Supreme Court, Solicitor General Donald B. Verrilli argues that the law was passed to address a national health care crisis. He points out that the current costs of the uninsured have shifted "tens of billions of dollars of costs" from uncompensated care  to other market participants annually.

"The Act breaks this cycle through a comprehensive framework of economic regulation and incentives that will improve the functioning of the national market for health care by regulating the terms on which insurance is offered, controlling costs, and rationalizing the timing and method of payment for health care services," Verrilli writes.

Lawyers for 26 states, the National Federation of Independent Business and two individuals are challenging the law in the Supreme Court. A lower court ruled that the health care law's central provision, the individual mandate (also called the minimum coverage provision), was not a valid exercise of Congress' authority.

While the Supreme Court will hear arguments about several aspects of the law at the end of March, Friday's filing dealt just with the constitutionality of the individual mandate. Other briefs will be filed at a later date.

Verrilli argues that the individual mandate plays a critical role in relation to the rest of the law by serving as an incentive for individuals to finance their participation in the health care market by means of insurance. He says the mandate "works in tandem with the Act's other provisions to expand the availability and affordability of health insurance coverage."

Although the challengers haven't filed briefs yet, they have consistently attacked  the administration's main argument that Congress was authorized under the Commerce Clause of the Constitution to pass the law. The opponents say that while Congress may be able to regulate interstate commerce, it does not have the authority to force someone into the marketplace to buy a product.

Verrilli strikes back at that notion, arguing that everyone will sometime in her life need health care, and that the individual mandate is about how to finance health care in a particular way.

A senior administration official, speaking on background to reporters on Friday before the brief was filed, tried to articulate the limits of the government's power.

He was asked about an argument made by critics of the law who say that if the government could force someone to buy health insurance why couldn't it force someone to buy broccoli?

The official dismissed the hypothetical as "wildly unrealistic" and said, "Congress here was dealing with a real-life crisis where you had a comprehensive economic reform … that has a substantial effect on interstate commerce. "

"Nothing, " the official said, "that will be decided in this case has any bearing on whether people can be forced to buy broccoli."

Verrilli warns the Court that Congress decided on the individual mandate after a vigorous national debate.

"That was a policy choice the Constitution entrusts the democratically accountable Branches to make, and the Court should respect it, " he writes.

The Supreme Court will hear five-and-a-half hours of arguments regarding the health care law in March. It will devote two hours of argument on the individual mandate on Tuesday, March 27.