Linda Greenhouse on the Supreme Court and the law.

Which of these assertions is the less plausible?

1. Representative Randy Neugebauer of Texas wasn’t aiming at Representative Bart Stupak when he interrupted Mr. Stupak’s floor speech during the closing hours of the health care debate by yelling “baby killer.” (Mr. Neugebauer said his target was the bill, not his colleague from Michigan, who had accepted a fig leaf of a compromise on the bill’s anti-abortion stance.)

2. The Supreme Court will find the new health care legislation unconstitutional.

In my book, these two propositions are running neck and neck into the realm of fantasy.

Fourteen state attorneys general — 13 in a coalition led by Bill McCollum of Florida and one, Kenneth T. Cuccinelli II of Virginia, going it alone — filed lawsuits this week asking federal judges to declare the new Patient Protection and Affordable Health Care Act unconstitutional. The plaintiffs do not exactly mince words. The new law violates “the core constitutional principle of federalism upon which this nation was founded,” the Florida complaint declares. It is “contrary to the foundational assumptions of the constitutional compact,” Virginia claims.

The Web is filled with commentary and debate over the merits of the states’ arguments that the new law exceeds Congress’s authority to regulate interstate commerce and violates the 10th Amendment’s protection for state sovereignty.

Interesting theoretical questions, to be sure. But the only real question is whether any of these arguments will find a warm reception from at least five Supreme Court justices. The answer, almost certainly, is no.

The challengers invoke and seek to build upon the Rehnquist court’s “federalism revolution” that flowered briefly during the 1990’s. In a series of 5-to-4 rulings, the court took a view of Congressional authority that was narrower than at any time since the early New Deal. The court struck down a federal law that barred guns near schools, on the ground that possession of a gun near a school was not the type of activity that the Constitution’s Commerce Clause authorized Congress to regulate. It ruled that Congress could not require states to give their employees the protections of the federal laws against discrimination on the basis of age or disability. It ruled that the federal government couldn’t “commandeer” state officials to perform federal functions like federally mandated background checks of gun purchasers.

So isn’t it reasonable to suppose that the constitutional attack on the health-insurance mandate, which states must facilitate by setting up insurance exchanges, will resonate with today’s majority?

It’s a fair question — to which my answer is, “That was then, this is now.”

John Roberts is an acutely image-conscious chief justice, as watchful and protective of the Supreme Court’s image as he is of his own.

The architects of the Rehnquist federalism revolution were Chief Justice William H. Rehnquist and his fellow Arizonan, Justice Sandra Day O’Connor (Chief Justice Rehnquist was actually from Milwaukee, but he decided during his Army service in North Africa that he liked the air of the desert rather than the cold and damp of the Great Lakes.) They were Westerners to whom the notion of states’ rights came naturally.

But Chief Justice John G. Roberts Jr. is not William Rehnquist, and Justice Samuel A. Alito Jr. is not Sandra Day O’Connor. John Roberts has made his career inside the Beltway ever since coming to Washington to clerk for Rehnquist. As for Sam Alito, I don’t believe that apart from a brief part-time gig as an adjunct law professor, this former federal prosecutor, Justice Department lawyer and federal judge has cashed a paycheck in his adult life that wasn’t issued by the federal government. Nothing in their backgrounds or in their jurisprudence so far indicates that they are about to sign up with either the Sagebrush Rebellion or the Tea Party.

Chief Justice Roberts appears particularly in tune with the exercise of national power. One of his handful of major dissenting opinions came in the 2007 case of Massachusetts v. Environmental Protection Agency, in which the court ordered the federal agency to regulate global warming or give a science-based explanation for its refusal to do so. That case was brought by a group of coastal states, which argued that climate change was lapping at their borders. Chief Justice Roberts objected that the states should not have been accorded standing to pursue their lawsuit. He denounced the “special solicitude” that the court’s majority showed the state plaintiffs. An early Roberts dissenting vote, just months into his first term, came in Gonzales v. Oregon, a 6-to-3 decision rejecting the United States attorney general’s effort to prevent doctors in Oregon from cooperating with that state’s assisted-suicide law.

Students of Rehnquist-style federalism will recall that the master himself blinked when his revolution got too close to the core of issues that people really care about. After all, hardly anyone had ever heard of the Gun-Free School Zones Act, the law the court invalidated in United States v. Lopez as beyond Congress’s commerce power. But plenty of people cared about the Family and Medical Leave Act, the law at issue in a 2003 case, Nevada Department of Human Resources v. Hibbs. Chief Justice Rehnquist surprised almost everyone in that case, not only voting to uphold the law’s application to state employees, but also writing a majority opinion displaying so much sympathy for the aims of the law it could have been ghost-written for him by Justice Ruth Bader Ginsburg. And with that decision seven years ago, the federalism revolution sputtered to an end.

John Roberts is an acutely image-conscious chief justice, as watchful and protective of the Supreme Court’s image as he is of his own. I find it almost impossible to believe that this careful student of history would place his court in the same position as the court that has been rewarded with history’s negative judgment for thwarting the early New Deal.

Midweek polls showed the public already rallying around the new health care law. That trend is likely to accelerate as people realize that the law’s benefits belie the scare stories — just around that time that the state challenges are likely to reach the Supreme Court. It won’t require a summa cum laude in history from Harvard to be able to tell history’s wrong side from its right.