The US has already tried registering Muslims. It didn’t work.

Last week, comedian Mohammad “Mo” Amer sat next to Eric Trump on a flight. He told him: “I’m not going to get a Muslim ID number. Bullshit. I’m not doing it.”

Perhaps, for some Muslims in America, his response provided some relief. According to Amer, President-elect Donald Trump’s third child said:

“That’s not gonna happen. Come on man, you can’t believe everything that you read.”

Of course, not fearing Donald Trump’s plans for Muslims would also require not believing what Trump has said.

He has called for “extreme vetting” of refugee seekers from war-torn Syria and other conflict zones. During the campaign, he said he would “absolutely” require Muslims to register in a database. He walked back his comments, tweeting that we need “surveillance” and a “watch list” to defeat terrorism.

After attacks in San Bernardino last year, Trump said he would implement a “total and complete shutdown of Muslims entering the United States” (a statement which is still available on his website). He clarified his position to Fox News: “This does not apply to people living in the country, except that we have to be vigilant, because when you have people putting bombs — having pipe bombs all over their apartment and other people see this and they don’t report them, there is something wrong. Very seriously wrong.”

That’s where the fear kicks in. Muslims have — in our recent past — experienced what special government scrutiny means. And, in one case, it tore families apart.

One of the security measures implemented after the 9/11 attacks was an under-the-radar special registration program for particular immigrants. Men ages 16 to 45 from 25 countries — all Muslim-majority countries save North Korea — were required to present themselves to government officials if they had nonimmigrant visas. We’re talking students and people here on work visas. The National Security Entry-Exit Registration System (NSEERS) was created as a way for the US government to more closely monitor these particular immigrants.

Essentially, it was a profiling program.

A Trump immigration adviser, Kansas Secretary of State Kris Kobach, told Reuters in November that the transition team would recommend bringing back NSEERS. A week later, he was photographed with Trump holding documents of his immigration plan. Among the legible text of the plan was that NSEERS is “updated and reintroduced” and that “all aliens from high-risk areas are tracked.”

Special registration fostered a public climate of suspicion, says Deepa Iyer, who was a civil rights attorney at the Department of Justice on 9/11. Now, she is an author and senior fellow at the Center for Social Inclusion. Her book, “We Too Sing America,” about the impact of post-9/11 policies on immigrants, was published last year.

“The government was saying that they could call these people in without any evidence of their criminality. One of the most harmful aspects of the policy is that it was a very blatant form of national origin and religious profiling, because of the way it was structured and the way it was implemented,” Iyer says.

The effect, rather than increasing security or catching terrorists, was hardship, she says. Some 83,000 people registered and about 13,000 were deported. Many people simply left rather than be subject to registration. There are no terrorism convictions tied to the program.

Kamal Essaheb was a student at Queens College on 9/11. He felt the trauma of the attacks, and then confusion from being called to register, as if he or his family could have possibly had anything to do with them.

Essaheb’s parents and two younger brothers immigrated from Morocco in 1992, when he was 11. They settled in Queens.

“We were just part of the fabric of the community,” he remembers. His father worked as a cab driver, and his mother took care of the children.

Language was difficult, he says, “but otherwise school had all these positive experiences. I remember my ESL — English as a second language — teacher working overtime with me. I remember her investment and care.”

“The rest of the school looked just the same as our class, it was just kids who were born here and didn’t need those language classes,” he says. “It just felt like I was part of the mix, this diverse mix. It didn’t really feel to me that anyone was more American than anyone else. … It just felt like home.”

“Through all of that, we didn’t have papers,” he says. He learned when he began applying to colleges that he was undocumented. “I was asked for certain documents. One of them was a social security number. When I went home and asked for it, I was told that I didn’t have one. I realized I was different from my classmates.”

Later, Essaheb and his family pieced together what had happened. They came to the country legally, on visas that eventually expired. His father was supposed to be sponsored by a company, but the paperwork was filed incorrectly.

It was a huge setback. But Essaheb focused on what was in front of him: how to go to college. In his teenage mind, the rest could all be fixed.

“Obviously, immigration law is not that simple,” he says. He’s now a lawyer with the National Immigration Law Center where he works on policy issues. “There are exceptions, but the general rule is once you lose your immigration status in this country, you really can’t get back on the horse, so to speak. But I didn’t know that, and I really felt, ‘This is just paperwork.'”

New York state allows undocumented people to pay in-state tuition for public colleges. He stitched together scholarships, some money from his family and lived at home while attending Queens College, two subway trains and a bus ride away.

He was a sophomore studying math and economics the day planes flew into the World Trade Center. After 9/11, his family had uncomfortable conversations about how to go from place to place. They minimized the time they spent alone in public, on buses or the subway.

“I think it was just minimizing risk,” he says. “Those of us who look brown and lived in New York at the time, that was really puzzling. Here we are being attacked the same way the rest of New Yorkers were on 9/11, and at the same time, the people who are our community members were also targeting us.”

And then the special registration program was announced — “and I say ‘announced’ loosely. It almost felt like a rumor,” Essaheb says. He heard different things at different times. It was unclear who had to register and when. “I remember all this confusion in my family and community about whether this would apply to us. … And obviously, the big question was, what would happen to you once you register?”

Essaheb was active and outgoing on campus, but he didn’t tell friends or classmates that he was Muslim, and he didn’t tell people that he was undocumented.

Instead, Essaheb put his energy into problem-solving.

“This was kind of an intense introduction to adulthood,” he says. “I remember going on AOL — that was the Google at the time — and thinking, like a good college student, about going to the primary source and landing on the ‘Federal Register Notice.’ It was this long, endless document that you had to scroll through for what felt like forever. After spending what felt like hours going through it, it was clear to me that my brothers, my dad and I had to register.”

Morroco, a Muslim-majority country, was on the list. They were in “Group 2,” which affected the time they had to register.

“Are we just all going to end up in a detention facility somewhere, and my mom’s never going to hear from us ever again? Does complying here destroy our family? We talked about what is going to happen, and what are they going to do to each of us,” Essaheb says. He was scared. “These are not fun family conversations. But we also decided that we have to go and register.”

He remembers that day — “one of the most memorable days of my life,” he says. They were supposed to appear at the immigration agency in downtown Manhattan. One day, after a quiet breakfast, Essaheb, his father and brothers made the trip.

“One moment that jumps to mind is saying goodbye to my mom, who was staying behind and had no idea what would happen. I think she was vaguely encouraging, vaguely positive. I remember my mom and dad trying to put on a brave face,” he says. “I remember just wanting to make sure we had all our documents, because there were documents you had to bring.”

“It was sort of a crack-of-dawn kind of thing. It was a really cold New York morning, and I remember it was still dark when we got there. There was already a long line wrapped around the building,” he says. “A long line of brown men who were just as confused as we were, just as scared as we were.”

Dozens of people at a time were ushered into the building and placed in a big room, “kind of a cross between a DMV office and hospital waiting area.” They were photographed, fingerprinted and called up to be interviewed one at a time. There were many men with guns there. “It felt like you had to be careful not to piss off the wrong person.”

“You’d see they’d take some people to the back, and some people they would turn away. I remember just being obsessed at observing each interview, not that I could hear what was happening. But just trying to piece together what was going on,” he remembers.

There was one lawyer in the room.

“In this sea of brown, predominantly Muslim men, there was this white, Jewish New York lawyer doing speed consultations. … I remember thinking it was so badass that she was out there, trying to help as many people as she could,” Essaheb says. “It made we want to be a lawyer.”

The lawyer told him that his family would likely face deportation hearings. “Even that was comforting, to at least know something,” he says.

His family had never had a lawyer before; they could have never afforded a consultation and didn’t know a lawyer could have helped. “We were more fortunate than a lot of other families, but $300 for a consultation would have been a big stretch.”

The four of them stayed in that room until past midnight, 14 or 15 hours.

“I don’t remember feeling bored. I remember just kind of taking it in. I remember feeling injustice for probably the first time in my life.”

They were finally called to be interviewed, individually. The interview was pretty basic: What’s your name? Which mosque do you attend? Are you a terrorist? Do you know any terrorists? Let me see your wallet.

“It was … violating. It wasn’t shocking, because it did feel like that was what the day was building up toward,” says Essaheb. He answered each question formally, no matter what the question was. “I was basically in my mind trying not to cause trouble.”

Edward Alden is a fellow at the Council on Foreign Relations and the author of  “The Closing of the American Border: Terrorism, Immigration, and Security Since 9/11.” He says the NSEERS program is an important reminder of what “extreme vetting” of immigrants looked like recently. The program, he says, was broad, ineffective and counterproductive — doing more harm to the people it targeted than it did to protect the US.

“It had horrible personal consequences for a lot of the people who got caught up in it,” Alden says. “If you’re going to try to secure the country against dangerous people, you have to have real intelligence.”

Aizaz Manzar came to the US from Pakistan to study. He was attending the University of Texas at Austin when 9/11 happened. He had to go to San Antonio to register, though he doesn’t remember it well. He does remember when FBI agents came to his apartment and questioned him and his wife.

They went through some 40 or 50 questions. “Do you know how to make a bomb?” was one of them. They asked his wife if she could speak English.

“More than the questionnaire, they were checking out how I was living,” says Manzar. “They were well-intentioned. They were not rude or anything, but they did do that subtle review.”

And when he traveled, he had to go through a special registration process to enter and exit the country.

“It would take hours of processing. It took up to six hours — I’ve missed many connecting flights,” he says. He would be taken into a special room and asked questions. They would collect personal information, even credit card numbers. “That kept on happening for four or five years until I got my green card.”

Manzar works for the computer company Dell, which sponsored his work visa. A few years ago, he became a US citizen. The special registration didn’t make sense to him — creating a list of 25 countries to screen seemed illogical.

“What about India, which has so many Muslims? Or Britain, which has a lot of immigrants? If you actually do it this way, people who want to do harm will find another way,” he says.

Even if you don’t care about racism and the social ramifications of a program like NSEERS, “it’s just a poor methodology,” he says.

At the end of Essaheb’s day in special registration, past midnight, officials kept his family’s four Moroccan passports. The family members were given a second interview date because they were undocumented. They tried to hail a cab, but the first driver refused to take them back to Queens, a common problem in New York City.

Essaheb took down the cab’s plate number to file a complaint. “It’s not something I would ever have thought to do before,” he says. “But I just remember feeling so sensitive to injustice.”

The second interview, a few months later, was similar in format but much more streamlined. By the end, they had dates that year to begin the process of deportation. Essaheb applied to law school while he was going through deportation hearings, though he did not know if he would be allowed to stay.

“I was becoming a lawyer, but at the same time it was still like I was kind of living this double life where every six months I would have to go to court and fight my case,” he says.

His father and two brothers had separate cases with different dates and judges. The whole family went together to each hearing.

He got his family a lawyer eventually — the same woman who was helping people in special registration. He ran into her at an event, and she remembered him. She took his family’s case pro bono.

She advised him all he could do was tell his family’s story and make it difficult for the government to send three kids from Queens to a country they no longer know. So, he told his friends and classmates his story. Essaheb and his family got an outpouring of support and media coverage. The government eventually dropped its case against him and his family.

Later, Essaheb qualified for DACA, the Deferred Action for Childhood Arrivals that gives temporary work permits and reprieve from deportation to people brought to the US as children.

“I’m always conscious of how lucky we are as a family that we’re able to be together and not have our life disrupted. Other people did experience that. Other people were torn from their homes and their communities and are living across borders and trying to piece together their lives in places that aren’t home,” he says.

Some entire families, regardless of their immigration status, left the country rather than go through the process. Other families were split in two when one partner was deported and another allowed to stay.

But the US is still home for Essaheb.

“It’s the place where I grew up. It’s the place where I picked up stupid little superstitions when I’m watching baseball games. It’s all of that, it’s where I’ve been formed,” he says. “I wasn’t born here, but it’s where I’ve spent most of my life. This is where I got to define who I am.”

“We’re throwing terms around like, ‘Muslim ban’ and ‘extreme vetting.’ I think it’s just important to know, we’ve been there not that long ago. And NSEERS is what it looks like, and the consequences of NSEERS are some of the consequences we might see if we have policies that discriminate against people based on where they’re from and what their faith is,” he says.

David Martin, an immigration law scholar at the University of Virginia, believes the US government should be able to take nationality into account in its security process. But he’s clear — that’s different from profiling based on national origin or religion.

“Sometimes you have to do very severe things, particularly in an emergency like 9/11,” he says, “but it’s very important to do that in a way that minimizes unintended fallout. … There should be a presumption against using things like NSEERS.”

Martin says Trump’s position on our ability to screen immigrants is “simply wrong.” The US is moving to a system in which all immigrants are registered and information is shared across agencies, he says.

NSEERS was replaced by US-VISIT in 2011, which requires all non-US citizens to provide biometric data, usually fingerprints, to get a visa or enter the country. The data is checked against databases of criminals, undocumented immigrants and people deemed security threats.

“There is vetting. We do know what’s going on,” Martin says. “If we demanded perfect security against foreigners with terrorist intentions, the only way to do that is to cut off all immigration. And, of course, that would be disastrous for our economy.”

Iyer’s concern is that while NSEERS has been suspended — the 25 countries have been delisted — it remains on the books. The next president could resume the program by adding target countries back to the list.

“It was never fully rescinded,” she says. “The framework for it, from a regulatory standpoint, still exists.”

Advocates are trying to convince President Barack Obama and the Department of Homeland Security to completely dismantle the program before he leaves office. That wouldn’t stop the Trump administration from bringing it back — like most executive decisions, NSEERS does not require Congressional approval. But Iyer says it would create a roadblock.

She and other advocates are asking the Obama administration to “finish the job that it started.”

At a Washington DC rally Monday, about 200 people marched against NSEERS. They asked Obama, as one speaker put it, “to give our communities a fighting chance” in the Trump administration.

Iyer says Muslims in the US have one significant thing that they didn’t have 15 years ago.

When it was introduced in 2002, NSEERS happened under the public radar, she says. “There were no solidarity conversations, no one saying, ‘I will register‘ — at least now we are more vigilant. And we should be. But we let it happen then. We just can’t let it happen again.”

With additional reporting by Rupa Shenoy.