A federal judge will determine the fate of a key part of President Donald Trump’s executive order on keeping together migrant families who are detained at the U.S.-Mexico border, a Justice Department official said Wednesday.

Gene Hamilton, counselor to the attorney general, said Judge Dolly Gee of the Central District of California has a “simple decision” when it comes to the Trump administration asking to modify her previous ruling about how the government can detain children.

“Are we going to be able to detain alien families together, or are we not?” Hamilton said. “It’s clearly lawful, Congress has not passed any statute that prohibits the detention of families together. But the simple fact of the matter is, Judge Gee has put the executive branch into an untenable position.”

That’s because Gee previously interpreted that a settlement, in a case known as Flores v. Reno, means the Department of Homeland Security cannot detain children who came with their parents for more than 20 days, Hamilton said.

Trump’s executive order directs Attorney General Jeff Sessions to file a request to alter the Flores settlement to allow the government “to detain alien families together throughout the pendency of criminal proceedings for improper entry or any removal or other immigration proceedings.” The department will file that “in the very near future” Hamilton said.

“Right now, we have lawful authority to detain a family unit together for up to 20 days,” Hamilton said. “I’m sure you can appreciate most of these cases involving someone who is seeking relief or protection from removal take longer than 20 days to adjudicate, to move through the court system.”

Without the ruling, Hamilton said, the government — to avoid holding children separately from their parents — would have to either “catch and release” every family or just release the children.

And that has the potential to prevent Homeland Security from effectively enforcing laws at the border, and encourage illegal immigration, among other fallout, Hamilton said.

The Trump administration still says only Congress can address the full spectrum of immigration law changes “for a permanent fix for the situation,” Hamilton said. The House is expected to vote on two proposals with provisions that would change the Flores settlement and close other loopholes, he said.

Democrats such as Rep. Jerrold Nadler of New York, the ranking member of the House Judiciary Committee, have warned against the provisions in the immigration bills. They say the legislation would authorize prolonged family detention in lieu of separations, and eliminate decades of court-ordered protections on how children may be housed and treated by the federal government.

“To throw vulnerable children in jail — even with their parents — is not acceptable and is prohibited,” Rep. Zoe Lofgren, D-Calif., a member of the Judiciary Committee, said. “The Flores Settlement clearly indicates that indefinite incarceration of children in prisons is not a good thing. Children require special protections and should not be placed in jail-like settings.”