LOOK TO the court decisions legalizing same-sex marriage in three states and you'll find the echoes of Margaret H. Marshall, chief justice of the Supreme Judicial Court of Massachusetts. Writing in 2003 that a state may not "deny the protections, benefits and obligations conferred by civil marriage to two individuals of the same sex, " Marshall warned that the decision "marks a change in the history of our marriage law."
Suddenly her ruling - that the Massachusetts Department of Public Health had to issue marriage licenses to Hillary and Julie Goodridge and six other same-sex couples - has come to seem the common sense of the matter. In California, Connecticut, and Iowa, state supreme courts have based their own decisions where Marshall had placed hers - on the principle of equal protection of the law, guaranteed in the Massachusetts Constitution and the 14th Amendment of the US Constitution. A recent poll conducted by the University of Iowa reports that 54 percent of adults in that state support same-sex marriage or civil unions; among adults under 30, some 75 percent support recognition of same-sex partnerships. As public opinion in state after state moves - as Maine and Vermont have done, as New Hampshire is close to doing - the argument from equality is coming to seem obvious.
But when Marshall wrote, it was not the common sense of the matter. Her decision set off celebrations of civil disobedience as mayors in San Francisco, Portland, Oregon, and other cities issued marriage licenses. It also set off a firestorm of protest: Every one of these marriages were nullified by state courts; Marshall was personally attacked for "unprincipled judicial activism" that jeopardized the integrity of her court.
Marshall's words on the subject of equality are among her most forceful. She relied on the Massachusetts Constitution, which " affirms the dignity and equality of all individuals. It forbids the creation of second-class citizens . . . [and] protects matters of personal liberty against government incursion as zealously, and often more so, than does the Federal Constitution."
Her sensitivity to "second-class" citizenship emerges, it seems, from her own experiences. She has written eloquently of her youth in South Africa, where she came to understand herself to have been shaped as a person "whose devotion to the rule of law originates in personal experience of the arbitrary, often brutal abuse of official power."
Convivial, with an ability to laugh at herself, she entered Yale Law School in 1973, among the first substantial cohort of women law students at a time when women were only 3 percent of the nation's lawyers.
Marshall's sensitivity to historical change is apparent in her reasoning in the Goodridge decision. In a context in which defenders of the status quo were likely to claim that heterosexual marriage practices have been permanent over time, a defense of same-sex marriage virtually requires engagement with assertions that "history teaches" that understandings of the meaning of marriage are not subject to change.
Drawing in part on the brief contributed by 25 "professors of the History of Marriage, Families and the Law" based in law schools and liberal arts faculties, the decision instructed its readers in the ways in which the practices of marriage in the state of Massachusetts have changed over time, just as the meanings of equality have necessarily changed over time in order, paradoxically, to safeguard the principle of equality.
Within two years of the Goodridge decision, scholars had begun to speak of "the Marshall court" and its contributions to state constitutional law. Notably the Marshall court has not only continued the SJC's tradition of construing state constitutional rights and liberties independently from the US Constitution, it has sustained what a 2005 article by Charles H. Baron and Lawrence Friedman in the Boston Bar Journal said is a "larger dialogue with sister-state and federal courts about the meaning of our constitutional rights and liberties."
As legislators continue to consider civil unions and same-sex marriage - as they are now doing in New York - listen for Marshall's voice, setting the debate firmly in the context of what we understand equality to mean.
Linda K. Kerber is professor of history at the University of Iowa. 
