Two legal advocacy groups asked a federal judge on Friday to allow them to begin a new challenge to President Trump’s latest attempt to restrict entry into the U.S. by foreign nationals. The groups will seek a court order to block enforcement of the new approach, which is scheduled to go into effect on October 18.

They will seek a new ruling that the shift in policy violates both the Constitution and federal immigration law.

The challenge comes even as the Supreme Court is pondering what to do with a pair of cases already under review, on the leon Friday to allow them to begin a new challenge to President Trump’s latest attempt to restrict entry into the U.S. by foreign nationals. The groups will seek a court order to block enforcement of the new appaality of the earlier, March 6 executive order that the President signed on immigration restrictions. The Justices have cancelled an October 10 hearing that had been set for those cases, and is awaiting new briefs from those involved, due next Thursday.

In a letter filed with a federal trial court in Greenbelt, MD, Friday afternoon, the American Civil Liberties Union and the National Immigration Law Center asked U.S. District Judge Theodore D. Chuang to allow them to formally begin a new test of the change in policy that the White House announced last Sunday. They notified the judge that the Trump Administration had told them that it would defend the new policy against this challenge, as it had with the March 6 version.

Judge Chuang was one of two federal judges who had ruled earlier that key provisions of the March 6 version were invalid as written, and could not be enforced. After two separate federal courts of appeals upheld the trial courts’ bars to enforcement, the Administration persuaded the Supreme Court to review those cases and, in the meantime, to permit some enforcement while the review goes forward.

Last Monday, the Supreme Court, while calling off the October 10 hearing, raised the question of whether that review will be foregone, in the wake of the new policy approach. The Justices seem likely to take some action after it gets the suggestions of both sides on how to deal with the pending cases.

The new order by the Administration is aimed at immigrants from eight nations, including three of those that were targeted for restrictions under the March 6 order. Unlike the prior order, the new policy only deals with potential entry to the U.S. of immigrants from specific nations; it does not deal with the restrictions on entry of refugees from around the globe. Both approaches are under review in the cases already at the Supreme Court.

The revised policy was crafted, in part, to try to get around legal complaints that challengers had made to the March 6 executive order. It added non-Muslim countries to the list on the entry-restricted list, and it made what it called “a more tailored approach” for each country involved, to more clearly demonstrate why restrictions had to be aimed at each country individually.

The new policy against immigrants’ entry was necessary because that part of the March 6 order had expired last Sunday. The part of the March order dealing with refugees is now set to expire on October 24.

In notifying the Maryland judge of their plan for a challenge to the revised policy on foreign immigrants, the two legal advocacy groups chose the vehicle of an already existing case – the one they had pursued against the March 6 order – but they essentially would be starting all over again, at the first level of the federal courts: a trial court.

By seeking to use the existing case as the basis for a new challenge, the two groups hope to take advantage of the fact that they would get the same judge, a judge who had ruled their way on the March 6 order and who was familiar with the whole controversy, and they would avoid some of the preliminary procedural requirements of starting a completely new lawsuit. The maneuver very likely would also lead to a quicker ruling on their new request.

In technical terms, what they sought first was permission to hold a conference with Judge Chuang and with lawyers for the Administration, to spell out their plans to file an amended version of their prior lawsuit. That new legal complaint will spell out their theories of why the September 24 approach is invalid, and will seek a temporary court order – technically, a preliminary injunction – against enforcement, while the challenge moves forward in the judge’s court.

The groups would need Judge Chuang’s permission to hold the conference and to file the new complaint.

As required by federal court rules, the two groups consulted with the Justice Department, as legal representative of the Administration, to get its response. The Department told them, they said, that it does not oppose their filing a new complaint, but will fight the plea for a new court bar to enforcement.