The renewed Republican control of Washington DC has produced one unique outcome — an unprecedented use of the Congressional Review Act. Congress passed the CRA in 1996 as a legislative veto on regulations passed within a particular time frame, but it had been used previously only once (in 2001) for a single regulation on ergonomic mandates. Since January, though, Congress has repealed 14 lame-duck regulations issued by the Barack Obama administration, fulfilling campaign promises made over the final months of the 2016 election cycle.

That’s as far as it goes, Politico’s Alex Guillen reported on Sunday. The time limit on review of new regulations will expire on midnight Thursday, after which the Trump administration will be forced to use the normal regulatory process — or deal with filibusters:

President Donald Trump’s inauguration gave congressional Republicans a once-in-a-generation opportunity to erase a spate of late Obama-era regulations — and they used it to make a significant dent before the legislative window closes in the coming week.

Since February, Republicans have used a once-obscure 1996 law to quash 13 “midnight” regulations on topics such as coal mining pollution, gun rights, internet privacy, Planned Parenthood funding, retirement savings and even bear hunting in Alaska. A 14th rule-blocking resolution is heading toward Trump’s desk, and GOP lawmakers hope to kill at least one more rule, on methane pollution, before the clock runs out Thursday.

The rollback affects just a fraction of the myriad Obama administration rules that GOP lawmakers and the Trump administration eventually hope to undo, in what White House adviser Steve Bannon has billed as the “deconstruction of the administrative state.” But never before have lawmakers made such dramatic use of the Congressional Review Act, which allows lawmakers and the White House to kill recently enacted regulations without having to overcome Senate filibusters.

Clearly, the CRA is the more preferable route — when it’s available — primarily because of the bypass of both the filibuster and the regulatory process. It’s also preferable because the CRA forbids agencies from reissuing the same rules later in “substantially” the same form. A later effort to issue the same rule would have to get passed as a statute by Congress, and that would be subject to filibusters. Using the regulatory process to repeal regulations and rules still requires publication, comment, review, and potential Congressional action, which takes months to accomplish.

But has the clock really run out on the CRA? That’s mostly true, Heritage’s Paul Larkin argued in February, but only for regulations properly submitted to both Congress and the Comptroller General. Rather than only having a few months to act on regulations, Larkin writes that Congress can reach back years — even decades — to repeal regulations that were never submitted properly for Congressional review:

The CRA provides Congress with an opportunity to invalidate an agency rule while satisfying the Article I Bicameralism and Presentment requirements. A joint resolution of disapproval signed into law by the President invalidates the rule and bars an agency from thereafter adopting a substantially similar one absent a new act of Congress. As the text of the act shows, Congress intended that the CRA apply broadly to whatever type of document an agency could use to strong-arm a regulated party into complying with the agency’s views.

Both regulations and interpretive rules fit under the umbrella of “rules” that Congress used to define the substantive scope of agency action. At the same time, Congress was precise in stating exactly when its opportunity to review and overturn a rule would commence: at the later of the date when the Federal Register publishes the rule or when the agency properly submits it to Congress. Together, those provisions enable Congress to reach back and review agency legislative and interpretive regulations that were never properly submitted to Congress under the CRA.

How many regulations might that leave vulnerable to CRA actions now? That’s a good question, and as it turns out, there may be a lot of them. A 2014 GAO report suggested that less than half of all new rules implemented by the executive branch agencies in the previous two years complied with the CRA’s notification provisions. That included dozens of “major or significant” rules that avoided Congressional review:

That could open up a very large can of worms, and some want Republicans to open it up after clearing the current CRA backlog:

Todd Gaziano, a top official at Pacific Legal who was the chief legislative counsel to the CRA’s sponsor, former Rep. David McIntosh (R-Ind.), said over the years agencies have failed to properly report hundreds if not thousands of rules to Congress as mandated by the CRA. This, he argues, renders the rules legally unenforceable.

Gaziano would like agencies to immediately dispense with all enforcement actions. He said since the launch of his website, redtaperollback.com, he has been fielding hundreds of calls from interested lawyers.

Wayne Crews, vice president for policy and director of technology studies at the Competitive Enterprise Institute, said if rules are identified that were not properly submitted to Congress, he expects there will be legal challenges by affected parties.

Gaziano said Pacific Legal is already looking into adding this argument to currently pending cases against enforced rules, and potentially bringing new lawsuits against rules he said are being enforced illegally.

The agencies could counter this by submitting the regulations to Congress and the Comptroller General now. That would, however, start the clock ticking on new CRA actions that could end up wiping out a significant number of regulations from Obama’s second term — including some that have been enforced for a few years. The courts may not like Pacific Legal’s attempts to invalidate the rules judicially, but the Trump administration could order these agencies to make their submissions now to moot the judiciary altogether.

We may not yet be done with the CRA. Given the stated mission of the White House to “deconstruct the administrative state,” it seems unlikely that they will take a pass on this shortcut.