Rahinah Ibrahim, a doctoral student at Stanford University, arrived at San Francisco International Airport with her 14-year-old daughter for a 9 a.m. flight home to Malaysia. She asked for a wheelchair, having recently had a hysterectomy.

Instead, when a ticket agent found her name on the no-fly list, Ms. Ibrahim was handcuffed, searched and jailed amid a flurry of phone calls involving the local police, the Federal Bureau of Investigation and the Department of Homeland Security. Two hours after her flight left, Ms. Ibrahim was released without explanation. She flew to Malaysia the next day.

But when she tried to return to the United States, she discovered that her visa had been revoked. And when she complained that she did not belong on a terrorist watch list, the government’s response came a year later in a form letter saying only that her case had been reviewed and that any changes warranted had been made.

Every year, thousands of people find themselves caught up in the United States government’s terrorist screening process. Some are victims of errors in judgment or mistaken identity, but just being on the list makes travel to and from the United States impossible.

The decision-making involved remains so secretive that people cannot be told whether they are on the watch list, why they may be on it or even whether they have been removed. The secrecy, government officials say, keeps terrorists off balance. But civil liberties advocates say it can hide mistakes and keep people wrongly singled out from seeking redress.

Now, five years after Ms. Ibrahim’s arrest at the United Airlines ticket counter, a lawsuit she filed is chipping away at that wall of secrecy. In December, a federal judge ordered the government to release files on Ms. Ibrahim’s detention.

A Muslim who came to the United States to study civil engineering, Ms. Ibrahim, 44, impressed colleagues at Stanford. “Of all the people you could think of who might be on a list of terrorism suspects, she would be pretty close to the bottom,” said Raymond Levitt, one of her faculty advisers.

The judge presiding over her lawsuit appeared skeptical, too.

“It looks like to me it was a monumental mistake, and they identified the wrong person,” the judge, William H. Alsup of United States District Court in San Francisco, said at a hearing in December. “I’m just guessing.”

The authorities will not say why they singled out Ms. Ibrahim. A week before her scheduled flight to Malaysia in January 2005, she was visited by two F.B.I. agents, said her lawyer, Marwa Elzankaly.

“They actually claimed they did not know why they were there to interview her,” Ms. Elzankaly said.

When the airport ticket agent discovered her name on the no-fly list, he called the San Francisco police, who contacted the Transportation Security Administration in Washington. There, they reached a watch officer working for United States Investigations Services, one of several private contractors the agency has hired for its 24-hour operations center.

The contractors’ duties “include receiving telephone inquiries and providing direction as to how to handle passengers,” said Kristin Lee, an agency spokeswoman.

The police incident report says the watch officer told the police to “deny the flight to Ibrahim, contact the F.B.I. and detain her for further questioning.”

She was driven to a police substation, where she was searched and placed in a holding cell. Eventually, an F.B.I. agent told the police to let her go, adding that she was being moved to the selectee list and could fly home.

Outraged, she decided to sue for wrongful arrest . But the law creating the T.S.A. made it virtually impossible to mount a legal challenge against it.

Instead, Ms. Ibrahim’s lawsuit focused on the F.B.I.’s Terrorist Screening Center, which does not have the same legal protections.

“If your name or my name or anybody’s name in this courtroom were put on that list, we would suffer grievously,” the chief judge, Alex Kozinski, said at a hearing in April 2008. “And we want to have some way of going to our government and possibly to our courts and saying, ‘Look, I shouldn’t be on that list.’ ”

Meanwhile, Ms. Ibrahim earned her doctorate degree from Stanford, but she has been unable to return to the United States to participate in the lawsuit.

Last month, Ms. Ibrahim accepted a $225,000 settlement from the San Francisco police and United States Investigations Services. But she is pursuing her claims against the federal government.


Rahinah Ibrahim is suing the F.B.I.