WALTHAM -- The chief justice of the state Supreme Judicial Court said yesterday that rhetoric about judges destroying the country and the suggestion that court decisions should conform to public opinion are threatening public trust in the judicial system, a cornerstone of democracy.
Justice Margaret H. Marshall, who has been widely criticized as a judicial activist since writing the court's 2003 decision allowing same-sex marriage, spoke before a crowd of 7,000 at Brandeis University's 54th commencement.
A native of South Africa who fought apartheid before coming to the United States, she said she is not concerned about criticism of individual judges or decisions, but about ''attacks leveled at the very foundation of our legal system -- the principle that judges should decide each case on its merits . . . independent of outside influence."
''I worry when people of influence use vague, loaded terms like 'judicial activism' to skew public debate or to intimidate judges," Marshall said. ''I worry when judicial independence is seen as a problem to be solved and not a value to be cherished."
One year after the ruling by the state's highest court took effect, Massachusetts remains the only state where gay and lesbian couples can legally marry. The 4-3 decision was seen as a landmark by those on both sides of the marriage debate, and opponents of same-sex marriage across the country moved quickly to build on public outrage in its wake.
In more than a dozen states, voters moved last year to ban same-sex marriage by approving constitutional amendments, against a backdrop of heightened mistrust of the courts. Governor Mitt Romney accused the Supreme Judicial Court of ''judicial overreaching" in The Wall Street Journal last year, and President George W. Bush lashed out at ''activist judges" -- those who use their decisions to push a social agenda -- in his State of the Union address.
Marshall did not make specific reference to the same-sex marriage decision yesterday, but she mounted a vigorous defense of the judiciary, calling it remarkable that in this country court decisions are obeyed even when they are controversial, and attributing that obedience to Americans' ''trust in the integrity of our judicial system."
''Americans, thousands of us every day, bring our conflicts to court because we believe we will receive a fair hearing and be treated equally by the judges. . . whose sole allegiance is to the rule of law," she said. ''Gratuitous attacks on judges undermine that trust."
Marshall endorsed comments made last week before the Senate Judiciary Committee by Joan H. Lefkow, the federal judge from Chicago whose mother and husband were killed in February by a man whose case she had dismissed. Lefkow cautioned against the extreme tenor of recent rhetoric and its tolerance by elected officials, and singled out for criticism comments that televangelist Pat Robertson made recently on ABC's ''This Week."
Marshall did not name Robertson in her speech, but quoted his statement that judges ''destroying the fabric that holds the nation together" are a threat ''probably more serious than a few bearded terrorists who fly into buildings."
''Judge Lefkow called on members of the Senate Judiciary Committee to 'publicly and persistently repudiate gratuitous attacks on the judiciary,' " Marshall told graduates and their families in her keynote address. ''I would urge you to do the same."
The speech was warmly received by an enthusiastic crowd at Brandeis, where student speakers and the university president, Jehuda Reinharz, stressed the importance of social activism. Marshall began with a joke about the blue and white balloons suspended from the Gosman Sports Center ceiling. She said she liked the colors, which included ''no red states" -- winning a big laugh.
A spokesman for Romney declined to comment yesterday on Marshall's speech.
But some analysts accused Marshall of ''muddying the waters" with her suggestion that critics want polls to drive judicial decisions. Judicial activism ''doesn't have anything to do with whether their opinions are popular or unpopular," said Brian Camenker, director of Article 8 Alliance, a Waltham group founded to remove Marshall and the other three justices who ruled for same-sex marriage from the bench.
'' 'Activist judges' is a specific term that refers to judges who rule outside the rule of law," he said. ''It has to do with whether they use objective, legal, constitutional means to base their decisions."
Some legal scholars believe courts must base their decisions strictly on specific language found in the constitution. Others say such an approach is impossible, because most constitutions did not anticipate current legal questions.
Some critics have said the same-sex marriage ruling in Massachusetts had no basis in the state's constitution. But one reason cited by the court for its decision was the state constitution's equal rights amendment, which says all people are born equal and have certain unalienable rights.
Marshall, who was awarded a doctor of laws degree at the commencement, came to the United States in the 1970s, attended Yale Law School, and later served as Harvard's general counsel. She was appointed to the Supreme Judicial Court in 1996 and became chief justice in 1999, the first woman to hold the position in the court's 313-year history.
Yesterday, Marshall asked graduates to undertake ''small acts" to promote understanding of the value of judicial independence.
''Each new generation must decide, each of you must decide, whether to embrace, to protect the rule of law, or to repudiate it," she said. ''And make no mistake, inaction and indifference are acts of repudiation."
Globe staff reporter David Abel contributed to this report. Jenna Russell can be reached at email@example.com.