The threats from her boyfriend came daily, fear having no respite, Blanca said. If she were to leave him, he told her from his jail cell, he would torture her, cut her into pieces and leave her to die. He was a member of the 18th Street gang in Honduras, and they did these sorts of things. She tried to resist.

Then he threw her against a wall when she visited him in jail, the police nowhere to be found. When his fellow gang member later raped and impregnated her, and then another threatened to kill her, she finally fled to the United States in 2013.

On Thursday, Blanca, 30, who now lives in the Bronx, will go before an immigration judge in New York to plead her case for asylum. On Monday, her chances of success changed instantly from challenging to nearly impossible.

On that day, in a speech to immigration judges gathered for annual training, Attorney General Jeff Sessions said that he was reversing recent immigration practice and declaring that domestic and gang violence were generally not grounds for asylum. Mr. Sessions’s action overturned a 2014 decision that had established domestic violence victims as a social group, based on the abuse a Guatemalan woman, Aminta Cifuentes, had faced for 10 years.