But being at the center of controversy is a position increasingly familiar to the 64-year-old judge.
Since President George W. Bush took office, Kessler has handled some of the highest-profile federal cases. Before the detainee decision, Kessler ruled in February that the secretive Energy Task Force led by Vice President Dick Cheney must make thousands of documents public.
Kessler is also handling a third case that casts the Bush administration in a bad light. That suit alleges that the Department of Justice and the Bush-Cheney Inaugural Committee illegally limited public protest at Bush's swearing-in January 2001.
U.S. District Court judges are assigned cases randomly, legal experts said. But for Kessler, a Clinton appointee with a history of ruling in favor of the public's right to know, the turn of the court calendar has turned her into a judicial stumbling block for the administration.
While conservative groups charge that her political stance regularly creeps into her rulings, her friends and colleagues describe her as a brave woman who judges according to the law.
"There's a beauty in the fact that someone as judicious as she is is a judge," said Judith Lichtman, a long-time friend and president of the National Partnership for Women and Families.
Ken Boehm, chairman of the conservative National Legal and Policy Center, disagreed.
"Kessler has a reputation for being one of the most political judges on the D.C. circuit," he said. "Judges can have whatever kind of politics they want, but politics are supposed to stop at the chamber door."
Early in her career, Kessler was involved with Democratic politics, and served as a legislative aide to a number of Democratic congressmen shortly after graduating from Harvard Law School in 1962.
Before becoming a D.C. Superior Court judge in 1977, she also worked for the National Labor Relations Board, an organization traditionally associated with Democrats.
Off the bench, Kessler continues to supports women's issues in the National Association of Women Judges. She assists with educational efforts to promote equal treatment in court for women and minorities, and is also involved in supporting programs that help women in prison, said Constance Belfiore, the executive director of the National Association of Women Judges.
Kessler herself declined to comment for this article. But her supporters insisted that her political opinions do not affect her rulings.
They pointed out that Kessler has also supported Bush administration positions, most notably in a January decision to toss out a Puerto Rican lawsuit aimed at stopping the military from using the island of Vieques for bombing practice.
"She has her own personal beliefs, like anyone does, but she takes her role as an impartial judge very, very seriously. At the same time, she has a lot of courage. If the law does support her, she will make the ruling," said Brenda Smith, Kessler's former law clerk and an associate professor at American University's School of Law.
Kessler's recent rulings have turned her into somewhat of a hero to a growing number of civil liberties groups, especially those which have involved requests for secret government information.
Steven Aftergood, the director of the Project on Government Secrecy, a small organization that is part of the Federation of American Scientists, called Kessler's March 2001 decision to release some government documents to nuclear energy workers "a work of art."
"Kessler is one of the few judges who has displayed an understanding of the Freedom of Information law and has applied it the way Congress originally intended. She distinguishes carefully between those things the law is intended to protect and those things which should be withheld," Aftergood said.
Other judge watchers, even conservatives, have praised Kessler's ability to come to compromise solutions in rulings. Catholic University Law School Dean Douglas W. Kmiec, who headed U.S. Department of Justice's office of legal counsel in the Reagan and Bush administrations, called Kessler's ruling in the Sept. 11 detainee case "reasonable."
"I'm generally a supporter of the attorney general's efforts, but in these matters, there is always a burden of proof on the prosecution," Kmiec said. "I think that Kessler made a reasonable ruling, one that is faithful to due process, and at the same time, does not close the door to national security concerns," he said.
Boehm, however, cited a number of recent rulings that he said showed a clear partisan slant. Among them was a case earlier this year in which Kessler ruled against a Bush administration nomination to the U.S. Civil Rights Commission. The ruling was later reversed by a three-judge panel, Boehm said.
But her supporters said that critics were just upset that the tough judge's rulings were not in their favor. They described Kessler as a wise woman who enjoys reading novels and going to the theater when she's not working.
"You may or may not agree with her decisions, but all say that they are very well reasoned. She does her homework," Belfiore said.