Attorney General Jeff Sessions ruled Monday that victims of domestic abuse and gang violence generally will not qualify for asylum under federal law, a decision that advocates say will affect tens of thousands of foreign nationals seeking safe harbor in the United States.

Sessions’ ruling overturned a 2016 decision by the Justice Department’s Board of Immigration Appeals that said a battered woman from El Salvador was eligible for asylum under federal law. The administrative appeals court is normally the highest authority in the issue, but the attorney general has the power to assign cases to himself and set precedents.

Before the ruling was made public, Sessions told immigration judges his decision “restores sound principles of asylum and long-standing principles of immigration law” and will help reduce a growing backlog of 700,000 court cases, triple the number in 2009.

“We have not acted hastily, but carefully,” he said in the statement. “In my judgment, this is a correct interpretation of the law.”

To qualify for asylum, foreign nationals must establish that they have a fear of persecution in their homeland based on their race, religion, national origin, political opinion or “membership in a particular social group,” a catch-all category that the immigration courts have attempted to define for decades.

Past appeals court rulings granted asylum to migrants who said they suffered persecution because they were victims of gang violence or domestic abuse in nations that were unwilling or unable to protect them.

But in the ruling, Sessions said such cases would be less common going forward.

“Generally, claims by aliens pertaining to domestic violence or gang violence perpetrated by non-governmental actors will not qualify for asylum,” he wrote. “The mere fact that a country may have problems effectively policing certain crimes – such as domestic violence or gang violence – or that certain populations are more likely to be victims of crime, cannot itself establish an asylum claim.”

Critics say Monday’s ruling is the Trump administration’s latest effort to erode asylum protections for hundreds of thousands of immigrants, particularly those fleeing violence in Central America. They said it overturns decades of legal efforts to persuade the courts to protect women fleeing abuse. They also worry the ruling could affect migrants escaping gang violence or attacks on gays and lesbians.

“It’s a massive setback for women’s rights because this is the kind of violence that women typically face,”said Deborah Anker, a law professor and the director of the Harvard Law School Immigration and Refugee Clinical Program.