In what will be an historic test of congressional power, the U.S. Supreme Court on Monday said it will decide the constitutionality of the Obama administration’s signature legislative success — the Patient Protection and Affordable Care Act.

Everything about the health care challenges before the Court looms large — from the political ramifications of a decision that likely will come in the middle of a presidential election campaign to the legal and social implications for Congress’ ability to address national problems. Even the time slotted for argument at the Court — 5 1/2 hours — is outsized.

The justices had five petitions before them when they met in conference last Thursday. They granted review in three, all from the U.S. Court of Appeals for the 11th Circuit. That court was the only one of four reviewing the statute to strike down the heart of the new law: the mandate that individuals who can afford health insurance must purchase coverage or pay a penalty.

The parties that will argue in the high court are the United States, represented by Solicitor General Donald Verrilli Jr.; 26 state attorneys general, represented by Paul Clement of Washington’s Bancroft; and the National Federation of Independent Business (NFIB), represented by Michael Carvin of Jones Day.

“After months of uncertainty and frustration, small-business owners are finally within the reach of some clarity on how this law will ultimately impact their lives and their livelihoods,” said Karen Harned, executive director of NFIB’s Small Business Legal Center, in a statement. “Our nation’s job-creators depend on a decision being reached before the harmful effects of this new law become irreversible.”

While Harned voiced confidence that the Court will invalidate the law, Elizabeth Wydra, chief counsel to the Constitutional Accountability Center, was equally confident that the law will survive. “Lower courts have rightly recognized that the text of Article I grants Congress power to regulate interstate commerce and to tax and spend to promote the general welfare,” Wydra said in a statement. “While Congress’s authority has limits, the powers expressly granted to Congress are nonetheless broad and substantial and provide the national government the authority to solve national problems, such as health care.”

The justices, in their Monday order, said they would hear arguments on the following issues:

• Whether Congress exceeded its authority under the commerce clause and necessary and proper clause in enacting the minimum essential coverage provision (the so-called individual mandate). This issue will receive two hours of argument.

• Whether the law must be invalidated in its entirety if the individual mandate is unconstitutional. This issue is slated for 90 minutes of argument.

• Whether the Anti-Injunction Act, which bars courts from hearing pre-enforcement tax challenges, deprives the justices of jurisdiction over the health care challenges. This issue will receive one hour of argument.

• Whether the law’s provisions expanding Medicaid coverage for the poor and disabled impose unconstitutional conditions on the states which “coerce” them into participation in return for federal funding. Justices gave this issue one hour of argument.

For some years now, the Court has been holding two hours of argument on argument days, while occasionally adding a third hour. The longest argument in recent years was the four hours granted in 2003 for a challenge to the federal campaign finance reform act.

All of the issues in which the court granted review were expected with the possible exception of the Medicaid challenge by the states. The law’s opponents called that grant “auspicious” while the law’s supporters labeled it “ominous.”

In Florida v. Department of Health and Human Services, the 26 state attorneys general argued, “Unlike when it has amended Medicaid in the past, Congress did not tie its new conditions only to those additional federal funds made newly available under the [health care law]. It instead made the new terms a condition of continued participation in Medicaid, thereby threatening each State with the loss of all federal Medicaid funds — on average, more than a billion dollars per year — unless it adopts the Act’s substantial expansions of state obligations.”

The state attorneys general ask the Court whether the limitation on Congress’ spending power recognized in South Dakota v. Dole (1987) still applies.

“That is the most surprising of the issues granted,” said Gregory Katsas of Jones Day, who, with Carvin, represents the NFIB. “I thought the states’ petition was very persuasive and made the point if ever there were a case to test the coercion point in South Dakota v. Dole, this is it.”

David Rivkin of Baker & Hostetler, who argued on behalf of the NFIB and the states in the district court, agreed, adding, “The language in South Carolina v. Dole on when persuasion turns to coercion should be very helpful. The fact that the Court took this up indicates it is looking very, very seriously at the issues. It augurs well.”

But if the Court says this is a valid question, “it calls into question every federal-state grant program,” said health law scholar Timothy Jost of Washington and Lee University School of Law.

Both the district court and the 11th Circuit ruled there was no legal support for the Medicaid arguments of the state attorneys general, he said. “All the circuits that have examined coercion say either the theory doesn’t exist or doesn’t apply. It’s surprising the Supreme Court reached out really far to get that question. Any time a state decides it doesn’t like a condition, it could bring a claim of coercion. Maybe they are taking cert to settle the question so it doesn’t come up again.”

An argument date (or dates) for the health care challenges has not been set yet by the Court, but arguments appear likely to be in March with a decision by the end of June.

Marcia Coyle can be contacted at mcoyle@alm.com.