Back in March 2011, when the biggest threats facing Obamacare were the Supreme Court and the 2012 elections, I argued that the demise of the Affordable Care Act would put people’s lives in immediate danger.

At the time, the law had relatively few beneficiaries—people under 26 covered by their parents’ health plans, a small population of people with pre-existing medical conditions. But some of them had already used their new coverage to finance the kinds of life-saving treatments that would leave them in need of chronic care for the rest of their lives. Take away the health law, and most of these organ transplant recipients and other patients would have become unable to afford their medications, and some of them would die.

Since then, millions of people have gained coverage under the law, and that group of chronic care patients has grown much larger. But despite the fact that the Court upheld the law, and President Obama won reelection, the ACA isn’t out of danger.

On Friday, the Supreme Court agreed to hear a case that will determine whether the federal government can continue to subsidize private ACA coverage in states that didn’t set up their own insurance exchanges.

That case is King v. Burwell, but the issue at stake has come to be defined by a comparable case called Halbig v. Burwell.