So 26 conservative state governors and attorneys general are seeking to get the coverage expansion tossed on the grounds that it's too coercive -- an unconstitutional application of the Constitution's Spending Clause.
Most legal experts say this is a long-shot. But however the court rules, the challenge in itself exposes the inconvenient fact that the conservative movement has been opportunistically on differing sides of federalism for a long time now. And a favorable court ruling for the plaintiffs would have severe and adverse implications for a number of right wing causes which rely heavily on federal government coercion.
"When it has suited social conservatives, they're all for coercion," says Sara Rosenbaum, a law professor at George Washington University, where she's also the chair of the Department of Health Policy.
The plaintiffs will ask the Supreme Court to rule narrowly that the Medicaid expansion is an unconstitutional use of Congress powers to tax and spend. If the court follows suit, though, it will invite a flood of challenges to other statutes, many of which conservatives adore, but all of which rely on Congress' power to impose conditions on money they provide to states.
"It opens a tremendous Pandora's box of other spending clause statutes that might be considered coercive with no clear limiting principles," Rosenbaum said. "At what point does something become a coercion."
Timothy Jost, a law professor at Washington and Lee University who has been monitoring the health care lawsuits very closely runs through some of these: "Title IX of the Civil Rights Act and national security programs and No Child Left Behind and all kinds of other programs."
The list is long. It includes requirements that universities receiving federal funds allow the military to recruit on their campuses. And, both Jost and Rosenbaum note, if conservatives get their way, it will also include a stronger version of the so-called Hyde Amendment, which severely restricts the use of federal funds to provide abortions.
"The House of Representatives has been fashioning a very different kind of Hyde amendment ... restrictions say that no federal funds go to the insurance program if that coverage offers more than the [federal] minimum for abortions," Rosenbaum said.
What are the implications here? Several states that help provide abortion coverage with their own funds would have to pare back that funding or drop out of Medicaid. That's a federal power conservatives are happy to exercise -- but one they'd stand to lose if they get their way in the Supreme Court next year.
"If the states were to prevail on the issue of expansion, then the [abortion] mandate would presumably fall," Rosenbaum said.
In other words, be careful what you wish for.
"The thing is that Medicaid is already conditioned on all kinds of thing," Jost said. "And some of them are things that people who are trying to strike the mandate think are pretty good ideas."