SEATTLE (AP) — A federal judge in Seattle blocked President Donald Trump’s effort to halt the nation’s refugee admissions system Tuesday.

The ruling came in a lawsuit brought by major refugee aid groups, who argued that Trump’s executive order suspending the federal refugee resettlement program ran afoul of the system Congress created for moving refugees into the U.S.

Lawyers for the administration argued that Trump’s order was well within his authority to deny entry to foreigners whose admission to the U.S. “would be detrimental to the interests of the United States.”

U.S. District Judge Jamal Whitehead said in his ruling after the hearing Tuesday that the president’s actions amounted to an “effective nullification of congressional will” in setting up the nation’s refugee admissions program.

“The president has substantial discretion ... to suspend refugee admissions,” Whitehead told the parties. “But that authority is not limitless.”

Justice Department lawyer August Flentje indicated to the judge that the government would consider whether to file an emergency appeal.

The plaintiffs include the International Refugee Assistance Project on behalf of Church World Service, the Jewish refugee resettlement agency HIAS, Lutheran Community Services Northwest, and individual refugees and family members. They said their ability to provide critical services to refugees — including those already in the U.S. — has been severely inhibited by Trump’s order.

Some refugees who had been approved to come to the U.S. had their travel canceled on short notice, and families who have waited years to reunite have had to remain apart, the lawsuit said.

Trump’s recent order said the refugee program — a form of legal migration to the U.S. — would be suspended because cities and communities had been taxed by “record levels of migration” and didn’t have the ability to “absorb large numbers of migrants, and in particular, refugees.”

The federal refugee program has been in place for decades and helps people who have escaped war, natural disaster or persecution. Despite long-standing support from both parties for accepting thoroughly vetted refugees, the program has become politicized in recent years.

Trump also temporarily halted it during his first term, and then dramatically lowered the number of refugees who could enter the U.S. each year.

Last week a federal judge in Washington, D.C., refused to immediately block the Trump administration’s actions in a similar lawsuit brought by the United States Conference of Catholic Bishops. That case faces another hearing Friday.