Margaret Marshall, author of Mass. gay marriage decision, to retire

At the same time, she said, she was retiring, effective at the end of October, with "deep regret" from work that she considered "thrilling."

Marshall, 66, was appointed to the Supreme Judicial Court as an associate justice in 1996 by former governor William F. Weld, becoming just the second woman on the SJC, which claims to be the oldest appellate court in the Western hemisphere, having dealt with its first case in 1692. Marshall was elevated to her current post in 1999 by then-governor Paul Cellucci.

In 2003, Marshall authored the court's majority decision that for the first time in Western legal circles, found that same-sex marriages were a lawful extension of the Massachusetts Declaration of Rights, the state's Constitution.

"The Massachusetts Constitution affirms the dignity and equality of all individuals," Marshall wrote for the 4-3 majority. "It forbids the creation of second-class citizens."

The ruling authorizing gay marriage is still echoing through the United States, on the state and federal level, and has become part of the legal debate on the meaning of equality in the 21st century, where historic views of the genders are being challenged by science and society.

Marshall made her announcement in a large conference room at the John Adams Courthouse, home of the high court. After her initial statement, the standing-room-only audience of fellow judges, lawyers, and court staff erupted into sustained applause.

Supreme Court Justice Robert Cordy said the six other members of the court learned only this morning, in phone calls from Marshall, about her decision. He said he was "very surprised" but understood it when he thought about her commitment to her husband.

"It makes me very sad," said Justice Margot Botsford, who was also on hand. "She's a wonderful chief justice, but I understand her reasons and I respect that. But I think it's a real blow to the court."

Wearing a navy blue suit, with a white blouse and a pearl necklace, Marshall removed her glasses and wiped her eyes, laughing and smiling, as the crowd applauded.

Asked her thoughts on her association with the gay marriage case (Goodridge v. Department of Public Health) in the public mind, Marshall recalled the day that the case was argued in her courtroom. After the case was done, many people left the court, she said, but others stayed. "For them, the next case was just as important as the Goodridge case. ... For me, every case has that importance and you learn as a judge that certain cases spark interest and others don't. But the legal issues are important in each case."

"I hope that when people look at the body of my opinions, they'll see that it was just not one opinion but many opinions throughout my tenure," she said.

Marshall is a South African native whose opposition to the white-led government's policy of apartheid pushed her to immigrate to the United States where she became a lawyer and worked in a Boston law firm before joining Harvard University where she rose to lead the Cambridge institution's legal affairs team.

Asked at today's news conference how she felt about critics who say that judges engage in judicial activism, she said, "It is a buzzword and I think it's often attached to opinions where the person who's making the claim ... doesn't agree with the outcome," she said.

She said she grew up in South Africa at a time when there was no freedom of speech, press, or movement and that made her enjoy the "robustness" of constitutional protections in the United States.

"This is a great system of justice in Massachusetts,'' she said, while noting it is under stress from budget cuts. "Perhaps because I grew up in a country with no system of justice that I feel so passionate about it.''

As chief justice of the court, Marshall is also the titular head of the court system. Those duties are normally largely ceremonial – daily court management is handled by an administrative judge – but Marshall seized on her role to rebuild the standing of the judiciary on Beacon Hill as an equal branch of government.

She has sought, not always successfully, to reduce political interference in court hiring decisions, to heighten the training and educational background of court employees, and to build a monument to judicial independence.

With the state's finances tight due to the stumbling economy, Marshall has spoken out, strongly in recent months, warning that budget trimming would harm the courts. In an October address, she said that "In my judgment, justice is in jeopardy in Massachusetts."

She said at the news conference that she hoped Governor Deval Patrick would "take into consideration people who care deeply about the administration of justice'' when choosing her successor.

As news spread of Marshall's impending retirement, state political leaders heaped praise on her.

"Chief Justice Marshall has served the people and the principles of this Commonwealth with exceptional integrity and grace," Patrick, who is in Iraq visiting members of the Massachusetts National Guard, said in a statement. "From fighting apartheid in her native South Africa to assuring equal rights through her service on our highest court, her career has been full, and her dedication to the rule of law and the defense of human dignity is timeless."

"She leaves a great big hole," he added in a NECN-TV interview from Iraq. "It will be tough to fill it."

House Speaker Robert A. DeLeo called Marshall a "lovely lady" and "one of the brightest legal minds in the country."

"I think she put the Massachusetts Supreme Judicial Court on the map, as we've always been, dealing with some of the landmark decisions in our court system," he said in an interview.

"It has been a privilege and an honor for me to know Justice Marshall and to work with her over the years. She will certainly stand in the annals of time as one of our most accomplished and significant justices," Senate President Therese Murray said in a statement.

Mary Bonauto, the lawyer for Boston-based Gay & Lesbian Advocates & Defenders who argued the Goodridge case before the high court, she would never forget reading the decision for the first time.

"I had never read those words in any opinion involving gay people at that point, let alone in a marriage case," Bonauto said.

"Those words," she went on, "are as clear and as moving a statement of the legal equality of all people as we have ever seen. The ruling profoundly changed the lives of gay and lesbian people in Massachusetts, not only in providing the precious freedom to marry but also [providing] a real sense, for the first time, of equal citizenship."

One conservative activist was not so laudatory. "She wrote the judicial opinion that single-handedly unleashed this radical social experiment, not only on the citizens of Massachusetts, but on the entire nation," Kris Mineau, president of Massachusetts Family Institute, said in a statement. "While I respect her years of public service, I believe this decision was based on her personal bias and diminished her as an impartial adjudicator of the Constitution."

For a list of Marshall's notable decisions, please click here. For her accomplishments, click here.