In 1992, by a 53%-47% split, Coloradans passed an amendment to their state Constitution that repealed laws in Aspen, Boulder and Denver that prohibited discrimination against gays. The amendment barred the state and its political subdivisions from adopting or enforcing any law “whereby homosexual, lesbian or bisexual orientation, conduct, practices or relationships” are the basis of a claim of discrimination. Does this sound familiar?

As the proponents of same-sex marriage rights determine the proper response to Proposition 8, it is illuminating to compare Colorado’s rejection of “gay rights” with California’s repudiation of “gay marriage.”

The day after the Nov. 4 election, a coalition of civil rights groups asked the California Supreme Court to declare that Proposition 8 was unlawfully enacted. The essence of their claim is that a constitutional change that rescinds individual rights must first be passed by a supermajority in the Legislature before being submitted to voters. This process-based claim may well have merit, but there exists a more direct means of challenging Proposition 8 based on the U.S. Constitution.

Following the enactment of Colorado’s Amendment 2, its opponents filed suit claiming that it unlawfully singled out gays and lesbians as a class to deny them rights that other citizens not only possess but take for granted. These rights include access to housing, government services, public accommodations and public and private employment opportunities without regard to an individual’s race, sex, religion, age, ancestry, political belief or other characteristic that defines each of us as a unique human being. Amendment 2, the opponents argued, therefore denied gays and lesbians the equal protection of the laws, which is a guarantee of the 14th Amendment to the U.S. Constitution.

To the surprise of many, the U.S. Supreme Court agreed.

Writing for a 6-3 majority in Romer vs. Evans (1996), Justice Anthony M. Kennedy explained that it “is not within our constitutional tradition to enact laws of this sort. Central both to the idea of the rule of law and to our own Constitution’s guarantee of equal protection is the principle that government and each of its parts remain open on impartial terms to all who seek its assistance.” Laws such as Amendment 2 “raise the inevitable inference that the disadvantage imposed is born of animosity toward the class of persons affected,” Kennedy wrote, adding a reference to another 1973 ruling. “If the constitutional conception of ‘equal protection of the laws’ means anything, it must at the very least mean that a bare ... desire to harm a politically unpopular group cannot constitute a legitimate governmental interest.”

Proposition 8 suffers these same constitutional flaws. It provides that gays and lesbians -- alone among consenting adult couples -- shall not have the opportunity to enjoy the rights, privileges and social approbation conferred by the status of lawful marriage. And despite their insistence that the initiative was “not an attack on the gay lifestyle,” its proponents were remarkably candid about their disapproval of homosexual families. The amendment, they argued in voter guides, “protects our children from being taught in public schools that ‘same-sex marriage’ is the same as traditional marriage.” It protects marriage “as an essential institution of society” because “the best situation for a child is to be raised by a married mother and father.”

But as California’s chief justice, Ronald M. George, explained in his opinion declaring the state’s previous statutory ban on same-sex marriage unconstitutional, limiting marriage to opposite-sex couples does nothing to protect the interests of children. “An individual’s capacity to establish a loving and long-term committed relationship with another person and responsibly to care for and raise children does not depend on the individual’s sexual orientation.” Moreover, “the exclusion of same-sex couples from the designation of marriage clearly is not necessary in order to afford full protection to all of the rights and benefits that currently are enjoyed by married opposite-sex couples.”

In other words, the reasons for denying gay and lesbian couples the right to marry that served as the “factual” basis for Proposition 8 are but pretexts for discrimination.

This is not to say, of course, that the federal courts would hold Proposition 8 to be in violation of the U.S. Constitution. There are differences between the marriage ban and Colorado’s prohibition of all sexual orientation anti-discrimination laws. As Kennedy noted in Romer vs. Evans, Amendment 2 “has the peculiar property of imposing a broad and undifferentiated disability on a single named group.” Proposition 8, in contrast, was narrowly focused on one civil right -- marriage. Moreover, any court -- especially our current U.S. Supreme Court -- may be reluctant to rule that Californians do not have the power to amend their own state Constitution as a remedy to a judicial interpretation of that very same document.

Yet the Colorado and California initiatives are alike in their essence. Each is, to quote Kennedy, “a classification of persons undertaken for its own sake, something the equal protection clause does not permit.” Proposition 8 was explicitly designed to relegate hundreds of thousands of Californians to an inferior legal and social status.

Many gay-rights activists are wary of the current Supreme Court, but five of the justices who formed the majority in Romer vs. Evans remain on the bench. As with so many cases, a ruling likely would hinge on the views of Kennedy, and there is no reason to believe that his judicial opinion has changed in any fundamental way. Besides, any constitutional challenge will take years to make its way to the U.S. Supreme Court. By that time, the broader political change that swept over the nation Nov. 4 may have reached the Supreme Court as well.

But even if it hasn’t, this 12-year-old precedent from a conservative high court could be the key to reaffirming that fundamental civil rights must be available to all citizens, regardless of race, sexual orientation or other intrinsic human qualities.

Brian E. Gray is a professor at the UC Hastings College of the Law in San Francisco.