When the legal challenges to the Affordable Care Act first started taking form, the assertion that Congress did not have the power to regulate the health insurance industry under either the Commerce Clause or the Necessary and Proper Clause was largely seen as an academic argument that had percolated in law schools thanks to a robust presence of the Federalist Society. After all, how could an industry that accounts for approximately 16 percent of economic activity in this country be said not to affect interstate commerce? Of course it can be regulated. Under even the most cynical view opponents of the Affordable Care Act peddled these arguments simply as political cover for the Court to invalidate the law since the tension between the Obama administration and the conservative wing of the Roberts Court was nearly palpable.

The Court declined the political cover, a fact I think speaks loudly to the rumors that Chief Justice Roberts was concerned about the partisanship and rancor brewing within and around the Court, and the implications of this for his legacy. But the Chief Justice hardly “joined the liberal wing” of the Court in upholding the law. In fact, his decision gives conservatives a potentially significant tool to further attack the social safety net in its limitation of the Commerce Clause.

People, for reasons of their own, often fail to do things that would be good for them or good for society. Those failures—joined with the similar failures of others—can readily have a substantial effect on interstate commerce. Under the Government’s logic, that authorizes Congress to use its commerce power to compel citizens to act as the Government would have them act.

That is not the country the Framers of our Constitution envisioned.

For centuries the Court has held that these congressional powers are broad and expansive, and that the main risk an expansive view of federalism poses is a political risk, not any real risk to individual rights or liberties. Then, in 1995, in the Court’s decision in United States v. Lopez, Chief Justice Roberts’ predecessor re-discovered those limits.

The Lopez decision invalidated the law banning the possession of guns near schools on the grounds that the activity challenged — gun possession and presumably gun use — was too far attenuated from the stream of commerce for Congress to regulate. Gun rights activists heralded the decision as a triumph of the Second Amendment, but social conservatives saw much more in the ruling. They saw the dawning of a new Golden Age limiting federal power and future legal avenues to challenge laws and policies they deeply opposed — like the Affordable Care Act.

In rejecting Congress’s ability to regulate the health insurance industry under the Commerce Clause while still upholding the mandate under Congressional taxing authority, Chief Justice Roberts builds on the Lopez line of reasoning in a way that did no broad  political damage to the Court — after all, the mandate survived and only those on the hard right seem intent on calling for Roberts’ impeachment — while still giving lots of juicy tidbits for federal judges to cite in future rulings hemming in other Congressional action. And since so much of Congressional action on domestic programs relies on its authority under the Commerce Clause and the Necessary and Proper Clause, it’s too soon to say if this distinction is again merely academic.

More importantly, Roberts extends the logic of Lopez which may prove to be more  significant than we realize even now as the Court considers future challenges to Medicaid funding, efforts to de-fund Planned Parenthood and affirmative action challenges. As the logic goes, just because social ills have a broad economic impact does not mean Congress is empowered to fix them.

It’s a logic that whole-heartedly rejects the very premise of the New Deal and our social safety system and one that was just re-inforced within the confines of a win on health care reform. Those of us that support the bill should celebrate the victory but we cannot get comfortable now. Chief Justice Roberts made it clear he upheld the law because he had to, both legally and politically. But in many ways the decision is a chilling repudiation of the heart and soul of its reform and a rallying cry for more vigorous challenges to the safety net. And we can expect conservatives to heed the call.