A federal judge late Tuesday night struck down a Trump administration rule that banned most migrants from receiving asylum at the southern border with Mexico.

U.S. District Court Judge Timothy Kelly said the administration failed to follow the procedural law governing how regulations can be implemented, which requires advance notice and a period for the public to comment on the proposal.

"These procedures are not a mere formality," Kelly, who was appointed by President Trump, said in his opinion.

The ruling will likely have little immediate impact amid the president's strict border restrictions over the coronavirus pandemic.

The rule was implemented last year by the Justice Department and Homeland Security in an attempt to crack down on migrants from Central America trying to enter the U.S. It makes all applicants at the southern border ineligible for asylum unless they had previously applied from another country or are the victims of sex trafficking.

"The United States is a generous country but is being completely overwhelmed by the burdens associated with apprehending and processing hundreds of thousands of aliens along the southern border," Attorney General William Barr said in a statement at the time.

Immigrants' rights groups promptly sued to overturn the rule in California and D.C.

They sought a preliminary injunction to keep it from going into effect while the legal challenge played out. Kelly, who sits on the federal district court in D.C., denied their request while a federal judge in California granted an injunction.

The Supreme Court ultimately ruled that the new policy could go into effect.

Hardy Vieux, an attorney at Human Rights First, one of the plaintiffs in the case, hailed the decision.

“Judge Kelly’s ruling is proof that the administration cannot do an end-run around the law,” Vieux said in a statement. “In the United States of America, we follow the rule of law, even when it benefits asylum-seekers demonized by this administration. We do not follow the rule of one capricious man, who treats the law as something on which to trample, on his way to a photo op."

The Capital Area Immigrants Rights Coalition, another plaintiff, added that the decision would remove a barrier for those seeking safety from persecution.

"By striking down this rule, Judge Kelly reaffirmed two fundamental principles," said Claudia Cubas, the group's litigation director. "The protection of asylum seekers fleeing for safety is intertwined with our national values and that the United States is a country where the rule of law cannot be tossed aside for political whims."

American Civil Liberties Union attorney Julie Veroff, who helped bring a separate challenge to the rule in California, said, "The court recognized that the Trump administration unlawfully skipped steps mandated by Congress to ensure transparency in its failed attempt to make an end-run around asylum protections.”

Tuesday's decision could still be appealed. A spokesperson for the Justice Department did not immediately respond when asked for comment.

Updated: 11:12 a.m.