WASHINGTON, March 14 - In a city of lawyers, Carla J. Martin has become the most talked-about lawyer in town.
Ms. Martin, an obscure official in the counsel's office at the Transportation Security Administration, now appears to bear responsibility for undercutting the government's long-running effort to execute the only man tried in an American courtroom for involvement in the Sept. 11 attacks.
Known among her peers as an aggressive, largely behind-the-scenes courtroom strategist, she is said by the judge in the case to have committed a potentially devastating blunder of the sort that law students are routinely warned about: coaching witnesses.
Dealing a major setback to the government's prosecution of Zacarias Moussaoui, Judge Leonie M. Brinkema ruled on Tuesday that because of three significant instances of misbehavior by government lawyers during the trial, most notably the missteps by Ms. Martin, she was barring the prosecutors from using any testimony or evidence from a handful of government aviation officials. [Page A24.]
Ms. Martin has declined to explain her actions in court or to reporters, and Judge Brinkema said Ms. Martin's lawyer expected his client to invoke her right against self-incrimination. But e-mail messages made public in the Moussaoui case this week, along with accounts from colleagues and supervisors, paint a picture of a lawyer who was often well regarded but also had a reputation for sometimes pushing too hard.
Ms. Martin, 51, is a former flight attendant at World Airways, where she often flew between the United States and Germany because she spoke German. She began working at the Federal Aviation Administration before she completed law school at American University's Washington College of Law in 1989.
Ms. Martin has almost no experience in criminal prosecutions because most of her work has involved defending the government in civil lawsuits. She moved to the Transportation Security Administration when it was created in 2002.
Some lawyers who have worked with Ms. Martin in other cases said they were stunned by the events in the Moussaoui case.
"She's articulate and forceful and aggressive and smart," said Thomas J. Whalen, an aviation lawyer at Condon & Forsyth who has worked on her side in some cases and against her in others. "I'm really surprised about what's happened. It's more than being tough and aggressive."
In the Moussaoui case, her communications with witnesses, and new evidence that surfaced Tuesday that she told some witnesses not to cooperate with defense lawyers, puts the prosecution in the position of having to investigate and sharply criticize a government lawyer who has worked on the case.
In a different case, in which Ms. Martin tried to keep vital evidence out of the hands of a lawyer on the ground that he had been associated with a civil rights group, she was accused by the other side of overstepping court boundaries and running roughshod over standard courtroom procedure in a zeal to protect national security.
Ms. Martin's mother, Jean Martin Lay, said she spoke to her daughter Monday night.
"She was so devastated," Ms. Lay said in a telephone interview from her home in Knoxville, Tenn. "She said she just didn't hear the judge."
Ms. Lay said her daughter was in the courtroom when Judge Brinkema issued the order on handling witnesses, but was probably concentrating on something else "instead of being mindful."
The judge's written order was issued last month, and Ms. Martin's contact with the witnesses occurred last week, according to e-mail messages made public by the court. The order was meant to sequester witnesses so their testimony would not be corrupted. It barred the witnesses from receiving the testimony of other witnesses or receiving any news accounts of the trial. The e-mail messages and the recent testimony show that Ms. Martin provided testimony and advice to seven witnesses.
Ms. Martin's mother said her impression was that her daughter found her work at the Transportation Security Administration "not the most satisfying or rewarding type job" because it did not involve any big cases. Her current salary, according to a government employee database, is about $120,000 a year.
Others, some speaking for attribution and others not, said they could see why Ms. Martin would find herself in trouble.
Claudio Manno, who at the time of the Sept. 11 attack was the assistant administrator for security at the F.A.A., testified Tuesday that Ms. Martin had taken up too much time second-guessing him and bombarding him with e-mail messages and requests.
"She tended to go off target and wasted our time," Mr. Manno said. "We didn't think it was pertinent."
A. P. Pishevar, a Maryland lawyer who tangled with Ms. Martin in another case, said her conduct in that case "sticks out like a sore thumb."
According to court records, she led an effort on behalf of the government to try to intervene in a defamation, discrimination and malicious prosecution lawsuit brought against Lufthansa by one of Mr. Pishevar's clients. The client was Kamyar Kalantar-Zadeh, an Iranian-born doctor, now an American citizen and associate professor of medicine at U.C.L.A. who was arrested and spent a night in jail after complaining about discriminatory treatment by Lufthansa officials at Dulles International Airport.
Lufthansa tried to have the case dismissed by filing a secret motion that said it had detained Mr. Kalantar to follow a secret F.A.A. security directive. According to court records, Ms. Martin urged Lufthansa to withhold the summary judgment motion and the security directive from both Mr. Kalantar and his lawyer, Mr. Pishevar.
Court records show that Ms. Martin said to one Lufthansa lawyer that ordinarily much of the evidence would be available to lawyers for a plaintiff. But she said the government sought to keep all the material from Mr. Pishevar, an American citizen and member of the bar in Washington, Maryland and the United States Supreme Court, because he had worked for an organization that fights discrimination in the United States against Iranians.
Judge Henry H. Kennedy Jr. of the Federal District Court in Washington ultimately denied the effort to dismiss the case and directed the government to turn over the material, which remains under seal, Mr. Pishevar said. The case has not yet been set for trial.
Mr. Pishevar said he still felt numb from his experience with Ms. Martin, who he said was "from behind the scenes, trying to pull many of the strings."
Told about the latest developments in the Moussaoui case, Mr. Pishevar paused, then said, "Res ipsa loquitur," a Latin legal term meaning, "The thing speaks for itself."
Others describe a more positive experience with Ms. Martin.
One of her earliest assignments was to monitor the trial brought by the survivors of those who died when Pan Am Flight 103 exploded over Lockerbie, Scotland. Her main job, according to a news account at the time and a lawyer involved in the case, was to get the judge to close the courtroom any time sensitive information was to come out.
James P. Kreindler, an aviation lawyer representing the survivors, said he could not account for what had happened in the Moussaoui trial. "When one is caught up in a massive bureaucracy, you may lose part of your perspective," Mr. Kreindler said. "She may have lost a proper perspective on the proper role for any attorney involved in either the criminal or the civil justice system."
"Carla is in my experience certainly not a bad person," he added, "and this is a very, very unfortunate thing to see happen."