As Salvadorans and Guatemalans fleeing U.S.-backed military regimes were denied asylum at rates above ninety-seven percent, hundreds of congregations declared themselves sanctuaries and moved refugees along a new underground railroad. The government answered with Operation Sombrero: paid informants wearing wires into Bible-study meetings and worship services, and a 1985 indictment of sixteen sanctuary workers in Arizona — priests, nuns, a Presbyterian minister, and lay volunteers.

At the 1985–86 Tucson trial the judge barred every defense that mattered — refugee law, religious motive, conditions in El Salvador — and eight defendants including Rev. John Fife and Fr. Anthony Clark were convicted of smuggling and harboring; all received probation, the government having concluded that imprisoning clergy would be a public-relations disaster. In Texas, Stacey Merkt and Jack Elder of Casa Óscar Romero had already been prosecuted — Merkt served jail time and became an Amnesty International prisoner of conscience. The trials failed as deterrence: sanctuary congregations doubled during the prosecution, and the movement's litigation ultimately forced the government to reopen tens of thousands of asylum cases.