The Supreme Court’s decision in National Federation of Independent Business v. Sebelius—the healthcare cases—was a tremendous political victory for the Obama administration and, more importantly, the tens of thousands of Americans who will be saved from illness and death by the law. But make no mistake: the decision could also be a significant legal victory for the political forces committed to limiting the state’s ability to care for the weak and fragile among us.

In the hours after the health care decision was handed down, many commentators crowed over Chief Justice John Roberts’s statesman-like craft in putting together a moderate opinion that, in different parts, managed to unite the left and the right of the Court. They are half right. The opinion may be statesman-like, but it’s ultimately radical, endorsing a view of Congress’s power that had few, if any, takers until it was embraced by the Republican Party and its Tea Party flag-bearers. Indeed, it may even contain a seed that could unravel important benefits of the Affordable Care Act.

The immediate effect of the decision, of course, is that the law’s implementation can proceed. On the one hand, Roberts, with four liberal justices, held that the individual mandate was constitutional as an exercise of Congress’s taxing power. On the other hand, Roberts joined the four conservative justices in stating that he believed that the same mandate could not be upheld under Congress’s Commerce Clause power. This should not to be overlooked. The Commerce Clause is the central plank of Congressional authority, employed to support everything from the Environmental Protection Agency to the civil rights laws. Flouting the usual rule that judges must avoid addressing unnecessary constitutional questions, Roberts made it clear that his new limitation on the Commerce Clause power was necessary to his opinion, and hence arguably binding on future courts.

What Roberts has done is much like what his predecessor Chief Justice John Marshall did in the landmark 1803 case of Marbury v. Madison, which also announced a dramatic new legal principle in a way that evaded immediate political opposition. Marshall’s opinion in Marbury is celebrated today because, while addressing a relatively minor dispute about federal officials, he used that case to establish the Court’s power of judicial review. But in establishing this power, Marshall effectively sided with Jefferson in the dispute at hand. Because Jefferson won, the White House was in no position to attack the Court for its then-startling and controversial assertion of the right of the judiciary to review legislative- and executive-branch actions.

That power then lay dormant in the law like a loaded gun—only to come into use in the late nineteenth century. Like Marshall, Roberts has slipped into the law a principle that he favors, while at the same time drawing the political sting from its immediate application. My hope, though, is that unlike Marbury’s endorsement of judicial review, the conservative and libertarian vision of the healthcare decision remains unique to those cases.

In the second part of his opinion, Roberts and a coalition of six justices invalidated one aspect of the Medicaid expansion. Medicaid is one of many important “conditional spending” programs, in which Congress uses its spending power to give money to the states, but attaches conditions to the grant. The Court had never invalidated such a program on constitutional grounds. Yesterday, though, the Court held that although the federal government could condition the Medicaid expansion on the specific funding assigned to that expansion, it could not defund a state’s Medicaid program entirely if the state refused to expand the program. In effect, the Court viewed the states as akin to Methadone addicts, so dependent on their ongoing fiscal fix that the federal government had a constitutional obligation to hook them up.

There is, then, the possibility that some states, such as Alabama, in a “cut off your nose to spite your face” gesture, will refuse the marginal increases in Medicaid funding that underwrite its expansion on ideological grounds. (That expansion is fully funded by federal dollars up to 2016, but that won’t stop hardcore opponents of “Obamacare.”) Those states are thus empowered by the Court to exclude many of their indigent population from Medicaid’s protections on a flawed point of libertarian principle. If states take this path, those not covered by the Medicaid expansion will continue to obtain healthcare in inefficient and expansive ways—undermining the cost-containment goals of the law and perhaps even threatening the stability of reduced premiums for others.

Remember, there were two key points of constitutional controversy before the Court in the health care cases: first, whether the mandate is valid under the Commerce Clause, and second, whether the Medicaid expansion is a use of federal spending that improperly coerces the states.

On both the Commerce Clause and the spending power points, Roberts’ opinions broke novel legal ground. His arguments are plainly wrong on both points. As (my former boss) Justice Ruth Bader Ginsburg explains in her sharply reasoned opinion, the federal government has power both under the Commerce Clause and its spending power to enact the Affordable Care Act—something that no one doubted until the Republican Party started to push the off-the-wall libertarian maxims of its Tea Party fringe.

Because Justice Ginsburg’s opinion does such a good job of explaining why Roberts is wrong—and, yes, you really should go read her opinion—let me focus on why Roberts’s opinion also has bad consequences. Surprisingly, Roberts’ innovations on spending may have more of an impact than his innovations on the Commerce Clause. Roberts and his conservative allies on the Court have introduced into the law a novel and unprecedented limitation on Congress’s power to “regulate commerce.” You can’t “regulate” inactivity, say Roberts et al., by requiring the purchase of a product in the private marketplace. Now, this new activity/inactivity distinction will not touch most federal regulation: The federal government will usually be able to point to some “activity” to ensure that a law is permissible under the Commerce Clause. Indeed, it is quite telling that no justice in any of today’s opinions even suggested that the Court ought to overturn any of its many Commerce Clause precedents that uphold Congressional action. Everything until now authorized, that is, plainly continues to be authorized. So much for the Commerce Clause revolution.

Instead, the most obvious example of a politically plausible federal proposal that is now out of bounds, at least under the Commerce Clause, is a federal mandate to purchase a private retirement account in lieu of Social Security. That is, the most plausible effect of the Commerce Clause part of the Court’s decision is to make certain privatization policies—ones that Republicans have generally favored—likely unconstitutional. I suspect this ironic consequence is not one that any of the conservative justices thought hard about.

But it is the spending clause part of the opinion that may have the more significant ramifications. While the Court has previously invalidated rules related to federal grants to states with strings attached on the ground that those strings were not articulated clearly enough, it has never before struck down a conditional spending effort as coercive—until yesterday. Apart from the puzzling question of how a non-natural entity such as a state can be “coerced,” Roberts’s explanation of this holding is unclear. Provided a federal grant is large enough and has continued for long enough, he might be read to say, the states acquire a right to it in perpetuity.

The reason this portion of the opinion is ground for concern is that it opens the door to extensive new litigation by the states to fight off regulatory mandates in other policy areas, from education to highway maintenance. The federal government often uses conditions on federal grants to pressure states into complying with important legal and policy mandates. Now it’s unclear how many of those conditions are good law. Precisely because it cannot be clearly understood, Roberts’s opinion invited new challenges by the states and new judicial decisions unraveling the regulatory net that keeps states in compliance with many important mandates on everything from civil rights to the environment.

In previous opinions, Chief Justice Roberts has expressed an allergic reaction to any judicial decision that does not come with clear boundary lines but that invites future litigation. Now, he has written an opinion that inserts into the law idiosyncratic libertarian ideals that invite a morass of new litigation and that pose the risk of exploding into much larger, and more harmful, doctrines. Unlike Marbury, today’s decision has an agenda that deserves no place in our law either tomorrow or any day in the future.