The Supreme Court on Monday starts three days of hearings on the constitutionality of the 2010 health care overhaul law, an epic clash that could recast the very structure of American government. But it begins with a 90-minute argument on what a lawyer in the case has called “the most boring jurisdictional stuff one can imagine.”

Indeed, the lawyer, Paul D. Clement, who represents the 26 states challenging the law, said this month in remarks at the Georgetown University Law Center that the first day’s arguments are “a kind of practical joke that the court is playing on the public.”

The main event — arguments over the constitutionality of the law’s requirement that most Americans obtain insurance or pay a penalty — will not come until Tuesday. On Monday, the justices will consider whether they are barred from hearing the case until the first penalties come due in 2015.

The answer to that question is not obvious. The United States Court of Appeals for the Fourth Circuit, in Richmond, Va., ruled last year that it was powerless to decide the law’s constitutionality for now, and a prominent judge on the United States Court of Appeals for the District of Columbia Circuit agreed.