The U.S. Environmental Protection Agency and the Army Corps of Engineers are in the midst of implementing a two-step process to repeal and replace the Obama administration’s 2015 “Waters of the United States” (WOTUS) Rule, pursuant to President Donald Trump’s Executive Order 13788.

The first step proposes a rule that would “re-codify” the Clean Water Act (CWA) WOTUS definition, which was in force prior to the 2015 WOTUS Rule, and has again been in force since the District of North Dakota and the U.S. Court of Appeals for the Sixth Circuit enjoined the 2015 WOTUS Rule. Once this proposed rule is finalized, the EPA and the Corps will begin work on new rulemaking that will re-evaluate the regulatory WOTUS definition. Meanwhile, the U.S. Supreme Court is poised to answer early next year whether jurisdiction over WOTUS Rule challenges belong in the district courts or in the Sixth Circuit. Given the numerous potential twists and turns concerning this pending litigation and the timing of the proposed “two-step” repeal of the 2015 WOTUS Rule, the future of WOTUS regulation is far from certain.

Still, the Supreme Court likely will hold that WOTUS Rule challenges should be brought in district courts. Such a ruling would immediately put federal district court proceedings into play again and raise the possibility of a permanent injunction against the WOTUS Rule.

For example, U.S. District Judge Ralph Erickson of the District of North Dakota ruled that his court had jurisdiction and enjoined the WOTUS Rule. Subsequently, however, the Sixth Circuit ruled that Section 509(b)(1) of the CWA requires circuit court jurisdiction for challenges to this type of rule. Actions proceeding under Section 509(b)(1)(E) or (F) (approval or promulgation of any effluent limitation under Sections 301, 302, 306, or 405 of the CWA, or issuing or denying a permit under Section 402 of the CWA, respectively) must be heard in the courts of appeals, while anything else should be heard by the district courts. The Supreme Court granted certiorari in the Sixth Circuit case. Prior to the Supreme Court argument, we thought the court took the case to reverse.

While predictions based on oral arguments are necessarily tentative, questioning at oral argument seemed to indicate the Supreme Court will reverse and hold that challenges to the WOTUS Rule should be heard in the district courts. Justice Stephen Breyer most strongly expressed that view, and Justices Anthony Kennedy, Samuel Alito and Neil Gorsuch and Chief Justice John Roberts all appeared to favor district court jurisdiction. Justice Ruth Bader Ginsburg also seemed to agree, though perhaps less fervently. She also asked both sides whether the pending proposed rule to rescind the WOTUS Rule would moot this case. Both sides answered in the negative, partly because any final rescission rule won’t take effect for a while, and partly because, even if it does, the same jurisdictional issue will arise concerning challenges to the rescission rule.

Justice Sonia Sotomayor seemed most inclined to accept the government’s view that the CWA provision at issue provides for circuit court review of the WOTUS Rule, but her view did not appear to be strongly held. Sotomayor also noted the “confusion” wasn’t just limited to the parties—it generated a “substantive split between a district court and an appeals court of another circuit.” Justice Elena Kagan asked questions that pointed both ways and seemed unsure of where she stood on the issue. Sotomayor and Kagan are the most likely to dissent if a majority will vote for district court jurisdiction is correct. Justice Clarence Thomas was silent during oral arguments, but would presumably side with Roberts and Alito, Gorsuch, Kennedy and Breyer.

A decision can be expected by January, and perhaps sooner, since this was only the second argument of the new Supreme Court term. If the court upholds district court jurisdiction by reversing the Sixth Circuit’s decision, the nationwide injunction against implementation of the WOTUS Rule issued by the Sixth Circuit will dissolve, but Erickson’s injunction issued in North Dakota and the 13 other states involved in that litigation will remain in force.

Assuming that this is how things play out, the district courts may be asked to enter a permanent injunction and final judgment against the WOTUS Rule. Such an action will be important, regardless of the timing (or outcome) of the pending proposal to rescind the WOTUS Rule, because that new rule is certain to be challenged by parties adverse to the Trump administration’s WOTUS reform efforts.

Paul M. Seby is a shareholder with Greenberg Traurig and represents the state of North Dakota in connection with the state’s challenges to the WOTUS Rule—including obtaining the only preliminary injunction of the rule by a federal district court.