WASHINGTON (AP) — A federal judge ruled Thursday that the U.S. government must stop using a Trump-era public health order to quickly expel migrants with children who are apprehended along the U.S.-Mexico border.

U.S. District Judge Emmet Sullivan gave the government two weeks to halt a practice that opponents say is unnecessary and improperly relies on the threat posed by COVID-19 to deprive people of their right to seek asylum in the United States.

Sullivan granted a preliminary injunction in response to a lawsuit filed by the American Civil Liberties Union and others on behalf of migrant families, saying they were likely to succeed in their challenge to the use of the public health law known as Title 42.

"President Biden should have ended this cruel and lawless policy long ago, and the court was correct to reject it today," said Omar Jadwat, director of the ACLU's Immigrants' Rights Project.

The Biden administration was evaluating the ruling and had no immediate comment on whether it plans to appeal.

The organization Human Rights First, which has documented cases of kidnapping and sexual assault among families and individuals sent to Mexico under the policy, urged the Biden administration to stop the use of Title 42 before the injunction takes effect in 14 days.

"In the wake of this decision, the Biden administration must choose to uphold the refugee laws enacted by Congress rather than permanently stain the president's legacy by continuing to perpetuate and escalate this illegal and inhumane Trump policy," said Eleanor Acer, the senior director for refugee protection with Human Rights First.

Title 42 was invoked early in the pandemic, under President Donald Trump, ostensibly to help control the spread of COVID-19 in detention facilities by turning back migrants encountered by the Border Patrol without giving them a chance to seek to stay in the U.S. by asking for asylum or for some other reason.

Opponents say there is no legitimate public health basis, and no legal authority, to deprive people of their right to seek protection in the United States from persecution in their homeland and that it is essentially a cover for a restrictive immigration policy.

The judge said in his ruling that the use of Title 42 in this case is "likely unlawful" and also unnecessary "in view of the wide availability of testing, vaccines, and other minimization measures" to address the potential spread of COVID-19.

President Joe Biden halted the practice of expelling children crossing by themselves, following reports that they were being sent alone into dangerous Mexican border cities, but continued turning away most other migrants.

In recent months, Mexico has begun accepting fewer migrant families with children and the U.S. has been allowing some to remain in the country as they seek to stay.

In August, the U.S. invoked Title 42 to expel 16,240 people traveling in family groups who were encountered along the southwest border, according to the most recent statistics from Customs and Border Protection.

In the same month, there were more than 86,000 migrants with minor children encountered along the border. Those who aren't immediately expelled are subject to U.S. regulations that allow them to pursue legal residency under asylum through the immigration court system.

The total number of migrants encountered along the U.S.-Mexico border in August was nearly 209,000, which was down 2% from the previous month but still exceeded recent periods of higher activity in 2019 and 2014, and was at levels not seen since 2000.

One outcome of the rapid expulsions is that people are making repeated attempts to illegally enter the country. Customs and Border Protection said 25% of those it encountered in August had been stopped at least once over the previous year, compared with 14% in earlier years. The Biden administration said in July that it would begin seeking to prosecute repeat offenders.