SAN DIEGO (AP) — Immigration judges generally cannot consider domestic and gang violence as grounds for asylum, U.S. Attorney General Jeff Sessions said Monday in a ruling that could affect large numbers of Central Americans who have increasingly turned to the United States for protection.

"Generally, claims by aliens pertaining to domestic violence or gang violence perpetrated by non-government actors will not qualify for asylum," Sessions wrote in 31-page decision. "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."

The widely expected move overruled a Board of Immigration Appeals decision in 2016 that gave asylum status to a woman from El Salvador who fled her husband. Sessions reopened the case for his review in March as the administration stepped up criticism of asylum practices.

Sessions took aim at one of five categories to qualify for asylum - persecution for membership in a social group - calling it "inherently ambiguous." The other categories are for race, religion, nationality and political affiliation.

Domestic violence is a "particularly difficult crime to prevent and prosecute, even in the United States," Sessions wrote, but its prevalence in El Salvador doesn't mean that its government was unwilling or unable to protect victims any less so than the United States.

Sessions said the woman obtained restraining orders against her husband and had him arrested at least once.

"No country provides its citizens with complete security from private criminal activity, and perfect protection is not required," he wrote.

The government does not say how many asylum claims are for domestic or gang violence but their advocates said there could be tens of thousands of domestic violence cases in the current immigration court backlog.

Karen Musalo, co-counsel for the Salvadoran woman and a professor at University of California Hastings College of Law, said the decision could undermine claims of women suffering violence throughout the world, including sex trafficking.

"This is not just about domestic violence, or El Salvador, or gangs," she said. "This is the attorney general trying to yank us back to the dark ages of rights for women."

Sessions sent the case back to an immigration judge, whose ruling can be appealed to the Justice Department's Board of Immigration Appeals and then to a federal appeals court, Musalo said. She anticipates other cases in the pipeline may reach the appeals court first.

Fifteen former immigration judges signed a letter calling Sessions' decision "an affront to the rule of law."

"For reasons understood only by himself, the Attorney General today erased an important legal development that was universally agreed to be correct," they wrote. "Today we are deeply disappointed that our country will no longer offer legal protection to women seeking refuge from terrible forms of domestic violence from which their home countries are unable or unwilling to protect them."

The decision came hours after Sessions' latest criticism on the asylum system in which he and other administration officials consider rife with abuse. The cases can take years to resolve in backlogged immigration courts that Sessions oversees and applicants often are released on bond in the meantime.

An administration official said last month that the backlog of asylum cases topped 300,000, nearly half the total backlog. Despite President Donald Trump's tough talk on immigration, border arrests topped 50,000 for a third straight month in May and lines of asylum seekers have grown at U.S. crossings with Mexico.

"Saying a few simple words — claiming a fear of return — is now transforming a straightforward arrest for illegal entry and immediate return into a prolonged legal process, where an alien may be released from custody into the United States and possibly never show up for an immigration hearing," Sessions said at a training event for immigration judges. "This is a large part of what has been accurately called 'catch and release.'"