Never underestimate the persistence of opponents of President Barack Obama’s signature legislative achievement, the Patient Protection and Affordable Care Act (ACA). Since the law was enacted in 2010, Republicans have introduced countless bills to repeal it, but have never had the votes to make their efforts anything but symbolic.

Having lost in the legislature, Obama’s opponents—many of them the very same conservatives who have long decried judicial activism—turned to the courts. In 2012, they lost a constitutional challenge to the ACA, when Chief Justice John Roberts parted company with his conservative colleagues and wrote a majority opinion holding that Congress’s power to impose and collect taxes authorized it to require individuals either to purchase health insurance or to pay a tax. The decision roiled the conservative movement, not least because of rumors that Roberts had initially voted to strike down the law, only to change his mind in the course of writing the opinion.

Now the Obamacare opponents are back before the Supreme Court again, advancing another challenge that, if successful, could spell the end of the ACA. King v. Burwell, or “Obamacare, Round 2,” will be argued on March 4. It pits Michael Carvin, one of the lawyers who argued the first challenge, against Solicitor General Don Verrilli, who successfully defended the law. Burwell has received far less attention than the earlier case, in part because it makes no constitutional claims and presents only a question of statutory construction. But its implications could be just as momentous.

The lawsuit is being funded by the Competitive Enterprise Institute, whose board member and former chairman, Michael Greve, had this to say about the ACA at a conference in 2010:

This bastard has to be killed as a matter of political hygiene. I do not care how this is done, whether it’s dismembered, whether we drive a stake through its heart, whether we tar and feather it and drive it out of town, whether we strangle it. I don’t care who does it, whether it’s some court someplace, or the United States Congress. Any which way, any dollar spent on that goal is worth spending, any brief filed toward that end is worth filing, any speech or panel contribution toward that end is of service to the United States.

The day that the Supreme Court rejected the constitutional challenge to the ACA, lawyers working with the CEI held a conference call about moving ahead with this new statutory claim.

This time, the law’s opponents seize on a single phrase buried in a subclause of the tax code that was amended by the ACA. They argue that it has the effect of denying to low- and middle-income taxpayers in thirty-four states the tax credits and subsidies designed to assist them in purchasing health insurance. Those…