How should we assess the Supreme Court’s historic decision to uphold the Affordable Care Act? The bottom line was a near total victory for liberals: the Court upheld the Obama administration’s most important accomplishment; for the first time in its history, the nation seeks to extend health insurance to all, thereby catching up, albeit in a halting and compromised fashion, with the rest of the developed world. The worst fears of many were avoided. A conservative Supreme Court did not vote along party lines to strike down a law that had generated more partisan division than any issue since the contested 2000 presidential election. The Court did not resurrect the market-fetishizing activism of the pre–New Deal era, when another conservative Court repeatedly upended social and economic legislation designed to extend basic protections to the vulnerable. And the challengers, who spent more than $200 million on advertising in hopes of prevailing in their implausible legal claims, failed in the Court—if only by a single vote—just as they failed in Congress. All of that deserves heartfelt celebration. We won!

It could have been otherwise. Leaks from inside the Court suggest that after oral arguments, Chief Justice John Roberts originally sided with Justices Anthony Kennedy, Antonin Scalia, Samuel Alito and Clarence Thomas, who wanted to declare unconstitutional the law’s individual mandate, which requires those who can afford it to purchase health insurance or pay an increased tax. However, at some point between March, when the case was argued, and June 28, when the decision was handed down, the chief justice apparently changed his vote. The four conservatives reportedly put intense pressure on Roberts to stay the course, but in the end they were left to write an impassioned dissent, contending that all 900 pages of the law were invalid—even though the challengers had attacked only two of the law’s hundreds of provisions.

And while Chief Justice Roberts voted to uphold the law’s individual mandate as an exercise of Congress’s power to tax, he unnecessarily went out of his way to agree with the conservative dissenters that Congress did not have authority to enact the mandate under either its power to regulate commerce or its power to enact all laws “necessary and proper” to further its other powers. This is a truly radical proposition. That five justices adopted it is deeply disturbing for what it says about those five—even if the determination had no impact in the case (because a majority upheld the mandate as a tax), and even if it is likely to have little impact down the road, as this was the first time in more than 200 years that Congress had attempted to require people to purchase a product they may not want.

The dissenting justices’ argument had no support in precedent. In the days since the Court abandoned its early New Deal activism, it has repeatedly affirmed Congress’s power to regulate all economic matters under the Constitution’s commerce clause and has further held that the “necessary and proper” clause allows Congress to enact any law that is “convenient” to furthering its other powers. As Justice Ruth Bader Ginsburg wrote in her separate opinion for the Court’s four liberal justices, those principles strongly support Congress’s power to enact the individual mandate, as it is clearly “convenient” to Congress’s regulation of the national healthcare market—and not a single justice would dispute Congress’s authority to regulate that market as a whole.

The mandate is “convenient” because without it, people could elect not to purchase insurance until they got sick, exploiting their right under the ACA to insurance regardless of any pre-existing condition. Moreover, because everyone eventually needs healthcare, and most can’t afford it when they do, and hospitals and doctors provide it even if a patient can’t pay, the uninsured are imposing substantial costs on the rest of us. Congress estimates that because insurance companies raise prices to cover these costs, the uninsured increase the average family’s insurance bill by $1,000 a year.

Given these straightforward arguments in favor of the law, the fact that five justices were nearly willing to strike it down underscores just how conservative the majority of this Court truly is. The conservative justices’ attempts to distinguish their votes in this case from prior cases in which they upheld equally broad exercises of federal power as necessary and proper (when it came to criminalizing possession of medical marijuana, for example, or authorizing the civil commitment of sexual predators) were entirely unconvincing.

Still, at the last moment Chief Justice Roberts blinked. And it seems quite unlikely the decision will have dangerous consequences for constitutional doctrine, though some prominent liberals disagree, pointing to the Court’s holding on Medicaid expansion. In it the Court held that Congress exceeded its power under the spending clause by authorizing the secretary of health and human services to withhold all of a state’s federal Medicaid funding if the state refused to expand Medicaid, but at the same time affirmed Congress’s ability to deny new funding to states that declined expansion. In an op-ed in the New York Times, Stanford law professor Pamela Karlan argued that the restriction on Congress’s power to make its funding conditional might imperil future federal spending programs.

But it seems unlikely that the Court’s holding on the spending clause—joined not only by the conservative justices but also by Stephen Breyer and Elena Kagan—will have much bite in the future. The Court held that the massive size of Medicaid as part of a state’s budget, coupled with the unforeseeable and dramatic changes in coverage, had the effect of coercing state compliance with the federal program. But no other joint federal/state spending program comes close to Medicaid in size, so it may well be a one-of-a-kind decision. And the Court fully affirmed Congress’s ability to make future federal funds conditional on compliance with its dictates. In most instances that should be sufficient. Some Republican governors, including Florida’s Rick Scott, have threatened to decline the funding and not expand Medicaid. We shall see; since Congress said it would pay 100 percent of the expanded program’s costs initially, and 90 percent long-term, to turn down that money is to place partisan symbolism over the needs of millions of these states’ residents and may prove politically untenable.

So, in the end, the Affordable Care Act decision marks a major victory for liberal progress. But it passed narrowly in Congress, and prevailed in the Supreme Court by only a single vote. Still, too many Americans (and too many justices) are too willing to view reasonable efforts to provide for the basic needs of our most vulnerable citizens as a threat to our fundamental freedoms. This is so even when the only “freedom” involved is the freedom to impose the costs of one’s own healthcare on others. In this instance, one vote was enough for the law to survive. But that only reinforces the crucial importance of ensuring that the next Supreme Court justice is not appointed by Mitt Romney.