Her family announced the death.

In 33 years on the bench, Judge Fletcher generally wrote liberal opinions on matters like employment discrimination, environmental protection and the death penalty. In 1996, conservatives saw a chance to oust her when President Bill Clinton nominated her son, William A. Fletcher, to the same bench, the United States Court of Appeals for the Ninth Circuit.

The conservatives, led by Sen. Orrin G. Hatch, the Utah Republican, who then headed the Judiciary Committee, said a mother and son serving on the same court violated a 1911 federal anti-nepotism law. After some contentious debate, Judge Fletcher agreed to resign as an active judge and accept senior status if her son was confirmed. Senior judges usually sit part time, do not handle death penalty cases and do not sit outside their home city, in her case Seattle.

By agreement, her seat was filled by a person acceptable to Senator Slade Gorton, Republican of Washington. Richard Tallman, a Republican, filled the position.

But Judge Fletcher had the last laugh. She never reduced her caseload, continued hearing capital cases and not only traveled to other cities to hear cases but also volunteered to help out on other circuits as a visiting judge. She ruled in more than 400 cases last year and presided at a hearing as recently as last week in San Francisco.

The Ninth Circuit has more judges, more cases and, with a jurisdiction that covers nine states and two Pacific territories, a bigger area than any other federal appeals court. It also has a higher proportion of judges appointed by Democratic presidents. Partly as a result, its rulings are often perceived as liberal.

Of the some 700 opinions written by Judge Fletcher, one, in 1979, concerned allegations of discrimination against women who worked for the transportation department of Santa Clara County, Calif. The fact that not one of the agency's 238 skilled craft workers was a woman, she wrote, represented proof of sexual discrimination, and she approved steps to correct the imbalance.

The case was one of the first judicial approvals of affirmative action for women. The United States Supreme Court affirmed Judge Fletcher's opinion in 1987.

In a ruling in 2007, she threw out the Bush administration's fuel-efficiency requirements for light trucks, saying they were too lenient because they did not take into account the impact of global warming, something that had not previously been considered in setting fuel-efficiency standards. She charged the National Traffic Safety Commission with coming up with a new approach that took note of global warming's costs.

Some of Judge Fletcher's rulings were reversed by the Supreme Court, including her attempt to stop an execution in 1998 of one of two men convicted in a murder. She was troubled, she said, that the men had been convicted in separate trials in which prosecutors used entirely different theories.

The Supreme Court let the execution proceed on the grounds that all appeals had been exhausted, calling the effort by Judge Fletcher and her colleagues to reopen the matter "a grave abuse of discretion."

Elizabeth Binns was born on March 29, 1923, in Tacoma, Wash. Her father was a lawyer who encouraged her to skip school to watch him try cases in court. She nonetheless graduated at 16. She attended Stanford University, where undergraduates were encouraged to take classes in the law school during World War II because so many law students were in the military.

Early in the war she married Robert L. Fletcher, who taught law for many years at the University of Washington. The couple had four young children when she decided to go back to law school. Her parents moved in to take care of the children while she enrolled in the University of Washington School of Law, where she graduated first in her class in 1956.

She soon discovered that women were not being hired by law firms. "Prejudice came down on me like a ton of bricks," she wrote.

She eventually became one of the first women in Seattle to be made a law partner, the first woman to be chosen president of the local bar association and the second woman appointed to the Ninth Circuit.

Mr. Fletcher died last year. Judge Fletcher is survived by her daughters, Susan French, a retired law professor, and Kathy Fletcher, an environmentalist; her sons, William, the judge, and Paul, a physician; eight grandchildren; and three great-grandchildren.

The Fletchers were not the first family members to serve on the same federal appeals court. "We've had a fair number of fathers and sons, some brothers and cousins, but never a mother-son situation," Bruce Ragsdale, chief historian for the Federal Judicial Center's History Office, said in a 1995 interview with The ABA Journal.

At the time of the tussle over William Fletcher's appointment, Democrats liked to point out that the elder President George Bush did something quite similar in 1992, naming Morris S. Arnold to a seat on the Ninth Circuit bench, where his older brother, Richard S. Arnold, was chief judge.

Defending the Fletchers in 1996, Senator Edward M. Kennedy said, deadpan, that he saw nothing wrong with concentrating power in one family.