Republicans' newest attempt at blocking Obamacare is not another Supreme Court case. It's not a full piece of legislation. Instead, it is a two-line item quietly tucked into a rules bill passed last week (and astutely noticed by the Hill's Sam Baker).

The provision, in full, is this: "Independent Payment Advisory Board- Section 1899A(d) of the Social Security Act shall not apply in the One Hundred Thirteenth Congress."

Did the House just abolish a health-care board in the swoop of 20 words? Not exactly: What this provision does, essentially, is change the ground rules for debating any cost-cutting recommendations from the Independent Payment Advisory Board, or IPAB.

While Congress does indeed have the unilateral power to set its own terms for debate, health policy experts say the IPAB still retains significant power. There's also a chance that the rule change could become moot: If health-care costs continue to grow slowly, the board won't end up sending any cost-cutting changes to the Hill in the first place.

The IPAB, if you recall, is the 15-person board that the Affordable Care Act charges with the unenviable task of recommending Medicare cuts. Republicans have derided the IPAB, whose members are appointed rather than elected, as a "rationing board" that will deny seniors the care they need.

When legislators created IPAB, they seemed to have a sense that it wouldn't be popular — cutting Medicare spending rarely is. So they wrote in all these provisions that would make it really, really hard to write the board off.

The Affordable Care Act directs the majority leader of each chamber to introduce the IPAB's legislative proposal "on the day on which a proposal is submitted." If the chamber isn't in session, it will be introduced "on the first day thereafter on which that House is in session." In other words, no dilly-dallying on the IPAB.

There are all sorts of special rules that govern the debate, ones that prevent legislators from changing the IPAB's recommendation and limits on the length of debate. There's even a provision that tells legislators they cannot repeal this specific part of the Affordable Care Act, saying that it "shall not be in order" to "repeal or otherwise change this subsection."

This is the legislative version of putting the IPAB behind bullet-proof glass; no other part of the health-care law gets such robust protections like a clause that tells Congress that repeal isn't on the table.

"They wanted to entrench it as best as they could," says Sarah Binder, an expert on congressional procedure at George Washington University.

But, as Binder puts it, legislators aren't exactly working with the highest grade protections. "You can't truly entrench a provision unless you put it in the Constitution," she notes.

And what the new House provision does is reject all those rules meant to protect the IPAB. Since Congress retains the right to set its own procedural rules, Binder says this change is well within their rights.

"It is a bit unorthodox because they're not necessarily amending the law, but rather reasserting their right to set the rules of debate," she says. "It's kosher in that sense."

While Democrats might not like to see the IPAB's recommendations undone, one aide familiar with the rules legislation acknowledges that it is well within the rights of the House to do this.

"I don't think we would quarrel with the idea that the House has this right under the Constitution," the aide said. "One of the few things the Constitution gives Congress is the  right to make their own rules."

At the same time, IPAB supporters don't see these rules changes as a huge threat to the board's existence. While they do give legislators more time to debate the legislation, they don't change one crucial feature of the IPAB: The board's cuts become automatic if Congress does not pass an alternative plan to reduce costs.

"The key feature [of IPAB] is that its recommendations are enacted unless Congress passes legislation," says former Obama OMB director Peter Orszag. "The House itself can't change that. How the House wants to consider the IPAB recommendations is up to the House. It's largely cosmetic."

There's also a decent chance that the House doesn't even get any recommendations from the IPAB at all. The board only kicks into gear, and recommends budget cuts, when the top Medicare actuary forecasts the program's costs growing a full percentage point faster than the rest of the economy. 

The Medicare actuary has until April 30, 2013, to make an official projection, but data available at this point suggest that Medicare spending could end up growing too slowly to trigger the board's recommendations. The past three years have represented an unusually slow rate of health-care cost growth, and some expect that trend to continue in coming years.

If Medicare spending continues to grow slowly, it creates the possibility of the 113th Congress never receiving IPAB recommendations — and these rule changes never seeing the light of the House floor.