People fleeing domestic or gang violence do not qualify for asylum in the United States, attorney general Jeff Sessions said on Monday, overturning an earlier immigration board decision. The ruling could impact thousands of people.

People seeking asylum in the US must demonstrate “membership in a group, which is composed of members who share a common immutable characteristic, is defined with particularity, and is socially distinct within the society in question.” That membership must be the reason for their persecution, the Department of Justice’s decision today explains. Asylum-seekers must also demonstrate that their home government is unwilling or unable to protect them.

That disqualifies most victims of “personal crimes,” the Justice Department said in an accompanying statement that specifically mentions domestic violence.

Our nation’s immigration laws provide for asylum to be granted to individuals who have been persecuted, or who have a well-founded fear of persecution, on account of their membership in a ‘particular social group,’ but most victims of personal crimes do not fit this definition—no matter how vile and reprehensible the crime perpetrated against them. The Department of Justice remains committed to reducing violence against women and enforcing laws against domestic violence, both in the United States and around the world.

Immigration judges in the US are required to rule on cases according to the attorney general’s interpretation. Earlier, a 2014 immigration review board ruled that “depending on the facts and evidence in an individual case, ‘married women in Guatemala who are unable to leave their relationship’ can constitute a cognizable particular social group that forms the basis of a claim for asylum.”

Sessions’ ruling on Monday was seen by immigration experts as a way to narrow how immigration judges interpret the law, and particularly discourage Central American women who have come to the US by the tens of thousands in recent years seeking asylum. It could also impact hundreds or thousands of women who are already in the US hoping for refuge here.

To seek asylum in the United States, one needs to qualify as a refugee, Congress decided in 1980. That’s defined as someone who is “unable or unwilling to return to his or her home country, and cannot obtain protection in that country, due to past persecution or a well-founded fear of being persecuted in the future ‘on account of race, religion, nationality, membership in a particular social group, or political opinion,'” by the United Nations 1951 Convention and 1967 Protocol.

“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 DOJ said today.