“Are you serious? Are you serious?” then-Speaker of the House Nancy Pelosi (D–CA) famously replied when asked where, specifically, the Constitution granted Congress the authority to mandate that every American purchase health insurance coverage.

The question was very serious, it turns out, even if Pelosi’s intent was sarcasm. Four federal courts have already struck down Obamacare in whole or in part on constitutional grounds. And now, with the Supreme Court widely expected to take the case in the coming weeks, three of the individuals who proved Pelosi wrong will address The Heritage Foundation on the present and future of Obamacare and constitutional federalism this Thursday at noon.

At the time that Pelosi spoke, just two years ago, her incredulity was hardly atypical. The Democrat-controlled Congress was racing to enact President Obama’s top legislative priority, a government-run health care system, and there was simply no place or time for quaint constitutional niceties. Only a few months later, recall, Speaker Pelosi’s minions would contrive the magnificently named “deem and pass” maneuver by which House Members wouldn’t even have to vote for a health care bill that the public had by then turned against.

The response to what had been a simple question—what is Congress’s power?—quickly devolved into farce. Reporters’ desks were blanketed with press releases from prominent law schools announcing leading academics’ media availability and their considered opinion that, based on text, history, and precedent, Congress could compel practically everything. Members of Congress, in turn, declaimed the irrelevance and obscurity of the constitutional text, and, besides, weren’t the courts supposed to figure these things out? And in the media, dissenters were tri-corner-topped eccentrics out of touch with 21st century America, if not reality itself.

But a few did give this small matter—whether the federal government remains one of limited powers—the serious consideration that it deserved, and their efforts pushed Obamacare to the precipice of judicial invalidation. Here are three:

Litigator David Rivkin, along with his colleague Lee Casey, raised the alarm in the pages of the Washington Post and Wall Street Journal, arguing that the individual mandate spelled the end of limited government. He soon joined Florida Attorney General Bill McCollum and more than half the states to challenge Obamacare in court, securing a stunning victory when a federal judge struck down the law in its entirety.

While Rivkin was making the case against the individual mandate in the press, Heritage’s Todd Gaziano focused his efforts on Congress and the academic world. His article, with lead authors Randy Barnett and Nathaniel Stewart, was the first to lay out methodically why the mandate exceeded even the farthest bounds of the Commerce Clause power that had been recognized by the courts. Since then, Gaziano has played an important role in organizing the conservative legal response to Obamacare.

Attorney Mike Carvin, along with Paul Clement, has been the one to steer the Obamacare litigation through the Eleventh Circuit and now into the Supreme Court. Representing the National Federation of Independent Business, Carvin has the difficult task of helping the Supreme Court formulate a precise limit on the Commerce Clause power where its previous jurisprudence has been imprecise in certain respects, while dodging the procedural barriers that the Obama Administration is attempting to throw up in the challengers’ way.

The constitutionality of the mandate itself has been discussed to death, but there are even bigger issues lurking in the background that these speakers will address at our event on Thursday. The Obamacare case will determine whether anything remains of the Constitution’s structural limitations on federal power; address whether the states retain any independence and power in the present day or are merely contractors of the federal government; and point the way to the future of constitutional federalism.

Pelosi couldn’t have been more wrong. This is serious.