Sometime in the next five weeks, the Supreme Court will decide the fate of the Affordable Care Act (again). The case, California v. Texas, challenges the constitutionality of the individual mandate. If it is deemed unconstitutional, the Court must then determine whether the mandate can be cleanly severed from the rest of the law or if the entire ACA falls with it.

While this is an important challenge to the law, my impression following last fall’s oral arguments is that even if the Court finds the mandate unconstitutional, the bulk of the law will survive. But the Supreme Court striking the individual mandate? That seems quite possible.

2009 me would have been terrified by this potential outcome.

2021 me is more…meh.

In 2009, I was on the small team of U.S. Senate staffers working to merge the bills passed by the Senate Finance and HELP Committees into one piece of legislation that could garner the votes of all 60 Democratic Senators in order to overcome a Republican filibuster. When that bill was was brought to the Senate floor, briefing materials I wrote for the Democratic caucus declared that the individual mandate was “essential to keep the cost of health insurance premiums affordable.”

Without a mandate to purchase health insurance, we reasoned, the ACA’s Marketplaces would face adverse selection – older, sicker individuals most likely to use health care services would purchase insurance, while younger, healthier people wouldn’t. This, we were told, would lead to a death spiral. (Not to be confused with death panels, which, to be clear, never existed).

With the benefit of hindsight, I think those of us working to craft the ACA can be forgiven for this overemphasis on the individual mandate. After all, nearly every health care economist touted the mandate’s necessity. The State of Massachusetts, the coverage expansion experiment on which the ACA was modeled, used a mandate. Even among those opposed to the mandate, no one suggested it wasn’t needed to prevent a death spiral; their opposition rested on personal freedom arguments.

As the final bill came together, the individual mandate felt, to many of us, like the bedrock upon which the law’s promise of improved access to affordable, comprehensive health insurance was built.

And then it was gone. Effective in 2019, Congress reduced the individual mandate penalty to $0. (Technically, the mandate still exists, leaving a confusing situation in which purchasing health insurance is legally required but there is no penalty for not doing so, and a convenient hook for the Texas legal challenge.) This effort came after many failed attempts to repeal the whole ACA; if they couldn’t dismantle the entire thing, congressional Republicans would chip away at the foundation on which the law was built, until it crumbled under its own weight.

Except that it didn’t. Despite many predictions to the contrary, in the aftermath of the elimination of the mandate penalty, premiums did not soar, the risk pool did not deteriorate, and the death spiral did not materialize. Overall, individual market premiums actually fell a bit in 2019 and 2020. Enrollment dipped in those years, but has recovered to pre-2019 levels. Participating insurers’ average gross margins largely held stable and the number of issuers selling plans through the marketplace has continued to climb.

The individual market continues to stabilize as insurers obtain more data on the beneficiaries they are covering and consumers get more information about coverage. In fact, the ACA had arguably its biggest moment in a decade when the American Rescue Plan substantially increased financial support to purchase health insurance, which is likely to further increase enrollment and improve market stability. Maybe this means carrots (the government-provided financial support to purchase health insurance) really do work better than sticks (the penalty for not purchasing)?

In the end, the success of the individual health insurance market, even given repeal of the mandate penalty, is the most damning evidence against the plaintiffs’ claims in the case now pending before the Court. The plaintiffs argue that the individual mandate is so essential that the entire ACA cannot function without it. The last three years have shown this simply is not true.