Tens of thousands of people who are currently waiting for their asylum cases in the US to be resolved — or waiting for their chance to apply — just got the door all but slammed on them.

Attorney General Jeff Sessions issued a ruling Monday in an immigration case, Matter of A- B-, that will make it hard or even impossible for Central Americans fleeing gang violence in their home countries, and women fleeing domestic violence, to get asylum in the US — or even be allowed to stay in the US to seek asylum instead of being summarily deported.

“Generally, claims by aliens pertaining to domestic violence or gang violence perpetrated by non-governmental actors will not qualify for asylum,” Sessions declared. Immigration judges and asylum officers need to tighten the standards of qualifying for asylum — or even being allowed to stay to present a case — accordingly.

Sessions referred the case to himself from the Board of Immigration Appeals, the quasi-appellate body of immigration courts run out of the Department of Justice, which means Sessions’s word is now law.

The ruling doesn’t flat-out say that an immigrant can’t be granted asylum on the basis of having faced domestic violence or gang violence in her home country. But it makes it clear that to the federal government, suffering either of those things — or having a credible fear that you might suffer them if returned — isn’t enough to count as persecution and allow you to stay in the United States.

Sessions is using his traditional, but rarely used, powers of self-referral to reshape the way immigration courts work. The new ruling will have an immediate impact on tens of thousands of cases currently in the pipeline.

It could even trap some of the families separated in the past few weeks by the Trump administration’s new “zero-tolerance” border policy — depriving the parents of any way to stay in the country, and drastically reducing their chances of relocating their children before they’re deported.

This is about the difference between the commonsense idea of asylum and the legal definition of the term

Because the fundamental principle of asylum is safety — that people endangered by persecution in their home countries should be able to find safety in the countries to which they flee — it might seem like common sense that victims of violence in other countries ought to qualify for asylum in the US, to protect them from danger.

But in both US and international law, persecution doesn’t just mean danger. It means danger based on one of five specific characteristics: race, religion, nationality, political opinion, or membership in a “particular social group.” An asylum seeker who is definitely in danger, but for some other reason, is technically out of luck.

”Particular social group” is the only characteristic that doesn’t have an obvious definition. So a lot of US asylum law has been dedicated to figuring out what, exactly, counts as a particular social group — and how to define it so that it encompasses groups that are persecuted in similar ways to religious or ethnic minorities, without being so broad that it makes “persecution” refer to any personal vendetta an immigrant might be leaving behind.

For several years, courts — not only immigration judges and the Board of Immigration Appeals, but also federal circuit courts — have been trying to hash out where victims of gang violence fit into this schema. Some Central American teenagers have claimed they qualify for asylum because any teenage boy not in a gang is likely to be targeted by one — or that they’re women of a certain age likely to be targeted by gangs for sexual violence.

Because there’s been disagreement between courts about when that counts as a basis for an asylum claim, people who arrive in the US and ask for asylum because they have a specific reason to worry they’re targeted by gangs tend to pass their initial interviews and be allowed to stay in the US to prove their claim.

Meanwhile, human rights groups have urged courts to see domestic violence as a form of gender-based violence that counts as persecution. In 2014, the BIA did just that — ruling that a woman abused by her husband qualified for asylum because she was a member of the group of “married women in Guatemala who are unable to leave their relationship.”

Sessions’s ruling overrules that 2014 decision and “any other Board precedent” that defines social group more broadly than his new ruling does. (Sessions doesn’t list exactly which precedents those are, inevitably opening the door for further cases to work out which precedents are and aren’t consistent.)

Indeed, Sessions goes to great length to explain that gang violence probably isn’t going to be a good basis for an asylum claim — because it is so common and so widespread that it could happen to basically anyone. “Victims of gang violence often come from all segments of society, and they possess no distinguishing characteristic or concrete trait that would readily identify them as members of such a group,” he writes.

Sessions makes a similar argument to reject the idea that gang violence counts as “persecution” in any event — because persecution is generally defined as coming from the government directly. In addition to showing that she’s being persecuted according to one of the five characteristics, an asylum applicant has to show that her government is either persecuting her itself or is unwilling or unable to protect her from her persecutors.

It’s generally accepted that the governments of Honduras, El Salvador, and Guatemala don’t have sufficient control to keep their residents safe from gang violence — in fact, they’re often compromised by gang ties. But Sessions argues that the burden of proof still lies on the asylum seeker: “The fact that the local police have not acted on a particular report of an individual crime does not necessarily mean that the government is unwilling or unable to control crime, any more than it would in the United States.”

It is going to get a lot easier to deport Central American asylum seekers — including families — without a full hearing

Because immigration courts aren’t fully independent courts, the decision Sessions just issued is now law for all immigration judges in the US — and everyone else considering asylum cases. Jeff Sessions “basically is the Supreme Court of the immigration courts,” in the words of Sarah Pierce of the Migration Policy Institute.

Federal circuit courts can attempt to challenge the decision, but even if they fully overrule Sessions — and he doesn’t issue a clarification that sets an equally restrictive standard — their rulings would only apply within the geographic scope of that circuit. And if this case somehow made it to the Supreme Court, the Court would probably have serious reservations about overruling a well-established administrative process — above and beyond its own ideas about what ought to count as a “particular social group.”

Meanwhile, immigration judges all over the US will have to make rulings based on their interpretations of what Sessions just wrote. But Sessions bluntly asserted, “Generally, claims by aliens pertaining to domestic violence or gang violence perpetrated by non-governmental actors will not qualify for asylum.” There’s not a ton of room for interpretation.

But Sessions isn’t just raising the standard for who can ultimately get asylum. He’s raising the standard for who can pass the initial screening at the border to apply for asylum, as opposed to simply being deported as an unauthorized immigrant. In other words, any Central American migrants who are currently en route to the US are going to be met with a higher bar to entry than the one they thought was in place when they left. Thousands of people who already arrived in the US but have been sent to criminal court to be convicted of illegal entry before they can make an asylum claim may now find themselves unable to pass a screening they would have passed when they arrived. That includes hundreds if not thousands of parents whose children have been separated from them.

Parents may now have very little time at all to locate their children and be reunified with them before getting deported. And even if they can figure out where their children are, they may have to make a choice between being deported as a family and allowing the children to attempt to stay — with a lower chance that they will succeed than they might have had before, but a chance nonetheless — while the parent returns home, deprived of any chance at all.