Everyone knows where Flor Crisostomo lives, even the federal immigration officials who have ordered her deported to Mexico. The reason they haven't detained her is her address — Adalberto United Methodist Church.

Another woman famously took refuge in that church as she championed immigration reform, and at least 13 other illegal immigrants are doing the same at churches around the country. So far, they have little to fear.

U.S. Immigration and Customs Enforcement officials have arrested illegal immigrants by the hundreds in raids at factories, restaurants, malls, farms and meat packing plants, but they have handled cases involving churches delicately.

"Our agency takes enforcement actions when we deem it appropriate," said Julie Myers, assistant secretary of homeland security for ICE. "I am personally not aware of an instance when ICE has gone into a church. That being said, if there was a particular, extremely egregious, ax murderer or something else, that's not to say we would not enforce the law at that time."

Avoiding churches is unofficial policy for federal immigration officials, according to Doris Meissner, a former commissioner at the Immigration and Naturalization Service, the agency that oversaw immigration until the Department of Homeland Security was formed in 2003.

Since the 1970s the unwritten rule has been "no churches, no playgrounds, no schools," said Meissner, now a senior fellow at the Migration Policy Institute in Washington.

Critics say making exceptions for churches, where immigrants openly — and in Crisostomo's case, very publicly — defy deportation, makes the agency look lax.

"These are people who deliberately violated the law," said Dave Gorak, executive director of the Midwest Coalition to Reduce Immigration. "We can't even enforce the laws without being criticized as Gestapo."

But Meissner said it wouldn't make sense for the agency to devote resources to arrest the relatively small number of people in sanctuary.

"An agency like ICE has far more work than it can possibly ever do," Meissner said. "You want to use those resources to thwart as much as possible egregious criminal behavior. A single person in a church doesn't really measure very high on a list."

Crisostomo came to the U.S. in 2000, paying a smuggler in Mexico to get her across the border. She was arrested in 2006 during a raid at a wooden pallet company in Chicago.

She has been at the West Side church for six months, since the Board of Immigration Appeals ordered her to leave the United States, holding news conferences, writing blogs and lecturing school groups about immigration issues.

Over the past year, ICE has focused on raids at workplaces.

"They pick work sites because they understand it is work that acts as a lure for unauthorized migrants to come to the U.S.," said Louis DeSipio, a political science professor who teaches Chicano/Latino studies at the University of California, Irvine. "ICE is sensitive to the publicity effect of their actions. They are careful on respecting religion and churches."

At the same time, ICE must "take into account that there is a public image issue and that they're being taunted," Meissner said.

Adalberto United Methodist gained widespread attention when it offered sanctuary to another immigrant, Elvira Arellano, who used it as a base to champion immigration reform.

Arellano stayed there for a year with her U.S.-born son, and frequently spoke about immigrant rights. She was arrested and deported to Mexico only after she left her sanctuary last August to travel to a rally in Los Angeles.

"We do conduct enforcement activities at a time and place of the government's choosing," said Myers, ICE's top official. "With Ms. Arellano, we believe that an appropriate time was when she was kind of traveling outside of the institution."

Arellano has been lauded as a heroine of the New Sanctuary Movement, which calls for immigration reform, and Crisostomo says she's following in Arellano's footsteps.

"We have to show the government that we are many, we are strong, we are humans and that we deserve respect in this country," said Crisostomo. "This is a church that was made to help the fight of people who are undocumented."

The New Sanctuary Movement, which makes living arrangements for illegal immigrants at churches, is modeled after a similar movement for Central Americans in the 1980s. Its goal is to call attention to immigration reform, but organizers believe sanctuary is a temporary solution, said Kristin Kumpf, a national organizer for the movement.

"The churches have been treated as sacred space," said Kumpf. But "no one can stay in sanctuary forever."