WASHINGTON, DC — Attorney General William Barr weighed in on an immigration case on Tuesday, establishing a new precedent that could affect thousands of migrants at the southwest border seeking asylum in the U.S.

In his decision, Barr said that asylum seekers who begin in expedited removal, in which they are not given the right to see a judge, and are then transferred to full removal proceedings, in which they wait to make their case before a judge, should not be released on bond. It means that thousands of asylum seekers who once would have been out on bond and living in the U.S. while awaiting a decision on their status will now be kept in detention centers, where the wait times are climbing from months to a year.

"This ruling gives [Immigration and Customs Enforcement] the legal authority to detain all of these people indefinitely," said Sarah Pierce, a policy analyst with the Migration Policy Institute, an immigration think tank. "That's if they have the capacity. So I think the actual effect of this ruling will be severely limited by ICE's capacity."

Due to the limited capacity, Barr said his decision should go into effect in 90 days in order to give ICE time to build bed space.

Michael Tan, an attorney for the ACLU, said his organization and others are preparing to sue the Trump administration over the new policy.

“The attorney general's decision is the latest attempt by this administration to punish asylum seekers for seeking refuge in the United States by locking them up in immigration prisons,” said Tan. “But the Constitution does not allow the government to incarcerate asylum seekers without basic due process. We'll see the administration in court.”

Under U.S. law, the attorney general has the right to overturn the decisions of immigration judges and establish sweeping new precedents, such as this.

The decision is expected to affect a broad swath of immigrants coming to the southwest border to claim asylum. Immigrants who enter the U.S. without documents, or with documents suspected to be fraudulent, are placed into expedited removal before they have an interview with U.S. asylum officers at which they try to establish they have credible fear for their safety if they return to their home countries. And more than 90 percent of asylum seekers pass the credible fear interview, according to Department of Homeland Security statistics.

Barr's decision reversed an immigration judge's decision to release an immigrant on bond while waiting for his proceedings. He also said that the Board of Immigration Appeals, a panel that reviews immigration court decisions, "wrongly decided" that only immigrants who enter the U.S. through legal ports of entry should be detained while others could be released on bond.

As a result of the decision, thousands of asylum seekers will remain in ICE detention while they await a decision in their case. Families with children under 18, however, will not be affected because of a federal court decision that prevents minors from being held longer than 20 days.

The Obama administration was criticized in 2014 for placing bonds so high that immigrants could not afford them.

Barr's decision could be problematic for ICE, where space to hold detained immigrants is already extremely limited. Many private prison companies and state and local jails are awarded ICE contracts to hold surplus immigrants.