NEW YORK (AP) — Don’t open the front door if immigration officials knock. If you are taken into custody, tell them your name and nothing else. Definitely don’t sign anything.

That is some of the advice being given in New York City and around the country at training sessions, put on by advocacy organizations, aimed at helping immigrants living in the country illegally get in as little trouble as possible if they encounter U.S. Immigration and Customs Enforcement officials.

Called “know your rights” training, the sessions have been pushed by some groups as a way to prepare for a possible crackdown on illegal immigration under President Donald Trump. Similar trainings are scheduled in New Mexico and El Paso.

The idea, organizers said, is to give immigrants guidance on how to legitimately push back against attempts to detain them, mostly using tactics designed to keep agents from learning anything they don’t already know. The government can’t deport someone unless they can prove they are in the U.S. illegally.

At a training session Tuesday in Queens, a little more than two dozen people sat in a room listening to Yaritza Mendez, an outreach coordinator at the pro-immigrant advocacy group Make the Road New York. She spoke about various ways ICE agents can find a person, and what to do if they come knocking.

Even people in the country illegally have constitutional rights, Mendez said, such as not being subjected to unreasonable searches and seizures, not answering questions and not signing any documents without speaking with an attorney.

Volunteers took part in a role-playing exercise. The audience broke into laughter when a woman wearing a vest with “ICE” taped on it burst into the room after knocking loudly on a door.

“I try to make it interactive because it’s long and very sad, in a way,” Mendez said.

A lady sitting at the back had a question. If immigration officials knocked on her door, what if she opened it a crack but kept the chain on?

No, Mendez said. Not even a crack. That’s guidance that closely mirrors something criminal defense attorneys have long been telling clients. Letting a law enforcement agent peek inside could give them the probable cause they need to enter without a warrant.

Other advice dispensed during the session: Make sure any warrants presented have the right name and addresses and are signed by a judge. Do not volunteer information. Do not show the agents any fake documents, since doing so is a crime that could land them in much deeper trouble.

Plan ahead for the worst. For example, she said, parents in danger of being detained should have paperwork in place to have someone look after their children, instead of scrambling to find someone in an emergency.

Most of the people in the audience were immigrants in the country illegally.

But they were also people like Pascalina Chirinos, 63, a legal permanent resident from Venezuela who has been in the U.S. for about five years.

She said she attended so she could share the information with friends and neighbors, but also to know her own rights if she were ever caught up even in passing in immigration enforcement efforts.

“In reality, all of us are afraid,” Chirinos said in Spanish, through an interpreter. “The air that we breathe is very tense.”

In Los Angeles, Pablo Alvarado, executive director of the National Day Laborer Organizing Network, said his organization is trying to train more people to conduct know-your-rights presentations at schools and churches to keep up with rising community demand.

“We’re training the trainers,” he said. “People don’t have to be lawyers to share what the constitutional rights of people are.”

Mendez said Make the Road has been getting calls from churches and other institutions like a local hospital to come and give the trainings in those places for their staffs and clients.

The atmosphere is “fearful,” she said. “You don’t know what is going to happen the next day.”

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