( CNN ) -- After President Barack Obama made his tepid endorsement of same-sex marriage last week , the pundits , from Fox News all the way to The New York Times , quickly pivoted from asking why to whether it will hurt him politically . But there is a more interesting question : How , in less than a decade , did America go from being a country in which some states punished gay sex with criminal penalties to one in which the highest elected official in the land now champions the right of same-sex couples to marry ? The answer can be found in the interaction between supporters of marriage equality and the Christian conservative movement over the past few decades . As late as the 1980s , same-sex marriage was on virtually no one 's radar screen . In 1972 , the U.S. Supreme Court found the idea of a legal right of same-sex couples to marry so outlandish that it dismissed a Minnesota case presenting the issue without bothering to write an opinion . At the time , the gay rights movement was understandably focused on combating private violence and public discrimination . No single factor explains the movement 's shift to the goal of marriage equality , but much of the credit must go to the very religious conservatives who assiduously campaigned against same-sex marriage , thus forcing the issue onto the front burner of American politics . It happened like this : In 1993 , in the case of Baehr v. Lewin , the Hawaii Supreme Court decided that the state 's prohibition on same-sex marriage was discriminatory . In 1998 , Hawaii 's voters passed a referendum giving the legislature the right to declare same-sex marriage illegal , but in the meantime , social conservatives had taken the issue to the national stage , where it promised to pay handsome dividends . Same-sex marriage was still so unpopular that in 1996 , tremulous Democrats joined Republicans in overwhelmingly passing the Defense of Marriage Act , or DOMA , signed by President Bill Clinton . That act defined marriage at the federal level to mean only heterosexual marriage and authorized states to deny recognition to same-sex marriages performed in other states -- even though , at the time , no state had authorized the practice . DOMA was thus a preemptive strike by the opponents of marriage equality . But the act helped to call into being the very marriage equality movement it aimed to combat . Encouraged by their surprising , if temporary , success in Hawaii , and outraged by the blatantly homophobic arguments that had been made in favor of DOMA , the lesbian/gay/bisexual/transgender movement reluctantly began to turn its energy and resources toward the goal of marriage equality . This was a fundamental shift , not made without controversy within the movement , where many worried that calling for marriage equality would unleash the fury of the Christian Right . Whereas many activists had given higher priority to such issues as employment discrimination , HIV/AIDS education and protection against hate crimes , the denial of marriage equality now came to be seen as a broad symbol of second-class citizenship for LGBT Americans . Obama 's declaration of his support for marriage equality the day after North Carolina residents banned both same-sex marriage and civil unions in a referendum is only the latest encapsulation of the dialectical interaction of movement and countermovement : Each effort to limit marriage equality has led to a countereffort on behalf of equal rights . As the first African-American president , Obama could not be seen to stand on the wrong side of the most prominent civil rights struggle of our time . Americans increasingly see laws that deny a person the right to marry someone of the same sex as reminiscent of the ugly laws that once forbade interracial marriage . The rest is , if not yet history , at least a well-known story . Although same-sex marriage remains illegal in most of the United States , and the issue may yet play to Mitt Romney 's advantage in November , time is on the side of equality . Those of us who favor same-sex marriage are rightly grateful to Obama for having come off the fence . But we should also thank religious conservatives for having put the president on the fence in the first place . Were it not for their opposition to same-sex marriage , it might have taken much longer for Americans to take up the cause . The opinions expressed in this commentary are solely those of Michael C. Dorf and Sidney Tarrow .
Michael Dorf and Sidney Tarrow : How did gay marriage issue move to forefront so quickly ? They say LGBT people had been quiet on it ; issue came up when Hawaii court ruled for it . They say conservatives pushed back hard , and the marriage equality movement started . Writers : If right had n't brought national opposition , issue would have remained under the radar .