The U.S. Supreme Court's 2012 decision upholding the Affordable Care Act has legs. Even though the court found the law constitutional, challengers said during a recent discussion of the case at Georgetown University Law Center that it would prove an important weapon in opposing additional expansive exercises of congressional power.

The event, sponsored by George­town's Supreme Court Institute, brought together many of the key liti­gators on both sides of the contentious battle over the health care reform. The occasion for what amounted to a reunion was publication this month of Unprecedented: The Constitutional Challenge to Obamacare, a book about the case by Josh Blackman, assistant professor at the South Texas College of Law.

Almost nostalgically, advocates rehashed National Federation of Indepen­dent Business v. Sebelius, firing off shots that echoed the sharp rhetoric that still characterizes discussions of the law.

"Nonsense on stilts" is how Jones Day partner Michael Carvin described Chief Justice John Roberts Jr.'s assertion for the majority that the law should be upheld under the broad power of Congress to tax. Georgetown law professor Randy Barnett, viewed as the architect of the legal challenge to the law, said flatly that "John Roberts wrote another law" in order to save it.

"I still think it shouldn't have been taken seriously," said Jenner & Block partner Paul Smith from the other side, referring to the constitutional challenge to the law's individual mandate under the commerce clause. "This should have been an easy case."

The decision dealt with a unique piece of legislation, causing some to fear — and others to hope — that the ruling would fade away in significance as a "good for this trip only" ticket from the Supreme Court.

But the ruling is already ­turning up in other cases unrelated to the health care law, said Erin Murphy of the Bancroft firm. She was second-chair to former solicitor general Paul Clement for the arguments against the Affordable Care Act. Clement still views the decision as a significant partial win, because four dissenting justices agreed with Roberts that the individual mandate was an unconstitutional exercise of the commerce clause, and could not be justified under the necessary-and-proper clause either.

Clement and Murphy have put those parts of the ruling to work, as recently as September 16, when they filed a reply brief in Bond v. U.S., a case that seeks to limit the power of Congress to enact laws to implement treaties if those laws have no basis in the other enumerated powers of Congress. The case will be argued on November 5.

The ruling in National Federation of Independent Business, Murphy said, will be "very much on the court's mind" as it weighs the government's assertion in Bond that the law before the court, implementing a chemical weapons treaty, is justified under both the commerce and necessary-and-proper clauses.

Georgetown's Barnett agreed the decision would be useful for its embrace of federalism in restricting the power of Congress to trample on state prerogatives. "The new federalism of the Rehnquist Court survived in the Roberts Court," Barnett said.

Jones Day's Carvin pointed to the next wave of litigation challenging other aspects of the Affordable Care Act, notably the requirement that employers provide health insurance plans that include contraception services. Nearly a dozen such suits based on the religious views of employers are pending, he said, and some are being reframed and refilled now that the government has promulgated its final "compromise" regulation. He said some lawsuits make First Amendment "compelled speech" claims against the law.

The September 16 event was also a symbol of the rapid embrace of Blackman, author of the book, by the Supreme Court community. Blackman is the latest young face to impress court practitioners and aficionados with his enthusiasm, Supreme Court savvy and bright ideas — but without the usual credentials (not an Ivy Leaguer, no experience in the solicitor general's office or as a Supreme Court law clerk.) Think Shon Hopwood and, a decade or so ago, Tom Goldstein.

Blackman was an early partisan in the battle over the Affordable Care Act, and he turns up briefly in his own narrative in the book of the strategizing among challengers to the law. In spite of that, his book plays it straight, offering a remarkably balanced and accessible account of the litigation. He does not, for example, hide the fact that Republicans did as much flip-flopping over the individual mandate as Democrats did. And he gets into some of the infighting between advocates on both sides.

"Gripping reading, really," said New York Times reporter Adam Liptak, moderator of the Georgetown event. "It is likely to last as the definitive account" of the landmark Supreme Court case, he said. Liptak jokingly recalled first meeting Blackman some years ago when Blackman was a George Mason University School of Law student waiting in line for a Supreme Court argument. Blackman came across as "a little goofy and not likely to amount to anything," said Liptak, whose opinion has long since changed.

Contact Tony Mauro at tmauro@alm.com.