Theodore B. Olson's office is a testament to his iconic status in the conservative legal movement. A framed photograph of Ronald Reagan, the first of two Republican presidents Olson served, is warmly inscribed with “;heartfelt thanks.”; Fifty-five white quills commemorate each of his appearances before the Supreme Court, where he most famously argued the 2000 election case that put George W. Bush in the White House. On the bookshelf sits a Defense Department medal honoring his legal defense of Bush's counterterrorism policies after Sept. 11.

But in a war room down the hall, where Olson is preparing for what he believes could be the most important case of his career, the binders stuffed with briefs, case law and notes offer a different take on a man many liberals love to hate. They are filled with arguments Olson hopes will lead to a Supreme Court decision with the potential to reshape the legal and social landscape along the lines of cases like Brown v. Board of Education and Roe v. Wade: the legalization of same-sex marriage nationwide.

Given the traditional battle lines on the issue, Olson's decision to file a lawsuit challenging California's recent ban on same-sex marriage has stirred up stereotype-rattled suspicion on both sides.

“;For conservatives who don't like what I'm doing, it's, 'If he just had someone in his family we'd forgive him,”;' Olson said. “;For liberals it's such a freakish thing that it's, 'He must have someone in his family, otherwise a conservative couldn't possibly have these views.' It's frustrating that people won't take it on face value.”;

While Olson came to the case by a serendipitous route that began late last year with Rob Reiner, a Hollywood director widely known for his Democratic activism, he said his support of same-sex marriage stemmed from long-standing personal and legal conviction. He sees nothing inconsistent with that stance and his devotion to conservative legal causes: The same antipathy toward government discrimination, he said, inspired him to take up another cause that many on the right applauded — a lengthy campaign to dismantle affirmative action programs.

A hearing in the marriage case, filed on behalf of two gay couples, is scheduled for Wednesday in federal court in San Francisco. Practicing his opening argument recently, Olson declared that California's ban is “;utterly without justification”; and stigmatizes gay men and lesbians as “;second-class and unworthy.”;

“;This case,”; he said afterward, “;could involve the rights and happiness and equal treatment of millions of people.”;

Chuck Cooper, who is representing proponents of California's ban, argues that such a “;radical redefinition of the ancient institution of marriage”; would require the court to find a right that does not exist in the Constitution — the very type of judicial activism Olson has long decried. “;I never expected him to take this case, or at least not this side of it,”; said Cooper, a friend of Olson from the Reagan Justice Department.

The lawsuit comes as societal views on same-sex marriage are rapidly evolving. It is now legal for gay couples to marry in six states, and the politics of the issue increasingly defy convention. President Barack Obama, for example, has said he opposes same-sex marriage, while former Vice President Dick Cheney, whose daughter is a lesbian, supports it.

Even so, Olson's involvement stands out. As one of the leading Supreme Court advocates of his generation, he commands wide respect in the legal community, and his views carry considerable weight with the justices, according to Steven G. Calabresi, a law professor at Northwestern University and a leader with Olson in the Federalist Society, a hothouse for conservative legal theory.

“;While some will think that this is an unpardonable error and rethink their views on Ted,”; Calabresi said, “;I think it will cause others to take a second look at the argument he is making.”;

In the gay community, though, conspiracy theories initially abounded that Olson had taken the case to sabotage it. While many have since come around, fears remain that a loss in the closely divided Supreme Court could deal a setback to the movement.

Opponents have flooded Olson with accusatory and sometimes hate-filled e-mail. “;A disgraceful betrayal of the legal principles you purported to stand for,”; read one message. “;Homo”; read another.

Conservative colleagues are kinder, but many remain bewildered. Former Judge Robert H. Bork, a close friend who has called same-sex marriage a “;judicial sin,”; said he could not bear to speak to Olson about the case.

“;I don't want to get into an argument,”; Bork said. “;But I'd like to know why.”;

UNEXPECTED ALLY

Last November, Reiner and his wife, Michele, invited two prominent Democratic consultants, Chad Griffin and Kristina Schake, to lunch at the Polo Lounge at the Beverly Hills Hotel. Ten days before, voters had passed Proposition 8, an amendment to the California Constitution negating a state Supreme Court decision that had briefly legalized same-sex marriage. Griffin, who had come out eight years earlier, said he felt like he had been gut-punched.

As the friends commiserated and discussed what to do next, an acquaintance named Kate Moulene stopped by. In a phone conversation later that afternoon, she suggested that Michele Reiner contact her sister's former husband, a leading constitutional lawyer. His name was Ted Olson, she said, and “;knowing him as I do, I bet he'd be on your side of this.”;

“;Ted Olson?”; Michele Reiner recalls exclaiming. “;Why on earth would I want to talk to him?”;

Olson's reputation, after all, went far beyond Bush v. Gore. As head of the Office of Legal Counsel at the Justice Department in the Reagan administration, Olson had been an architect of the president's drive to ease government regulation and end race-based school busing and affirmative action set-asides in federal contracting. He later provided assistance to those seeking to impeach President Bill Clinton.

As Bush's solicitor general, in charge of representing the government before the Supreme Court, Olson became identified with the administration's broad interpretation of its wartime power in the wake of the Sept. 11 attacks, in which his wife, Barbara, a conservative commentator, was killed. (Olson nonetheless privately counseled that terrorism suspects be given certain basic legal rights, administration officials said, correctly predicting that failure to do so would lead to Supreme Court setbacks.)

Still, Rob Reiner was intrigued. The tactician in him saw the wisdom of hiring a lawyer who had won 44 of the 55 Supreme Court cases he argued; the director grasped the dramatic impact of such a casting decision. He dispatched Griffin to consult with experts about the feasibility of a federal court challenge to Proposition 8 and to gauge Olson's interest.

“;I thought, if someone as conservative as Ted Olson were to get involved in this issue, it would go a long, long way in terms of presenting this in the right kind of light,”; Reiner said.

In fact, Olson's history was more complex than Reiner imagined.

Olson had become active in the Republican Party as a college and law student in California in the 1960s, long before the rise of the religious right and its focus on social issues. He gravitated toward a particularly Western brand of conservatism that valued small government and maximum individual liberty, becoming one of a few law students at the University of California, Berkeley to support Barry Goldwater's 1964 presidential bid.

At the time, the South was riven by racial strife, and during a college debate trip to Texas, Olson got his first close-up view of blatant discrimination. Lady Booth Olson, a lawyer whom Olson married in 2006, said he still tears up when telling how a black teammate was turned away from a restaurant in Amarillo. Olson “;tore into the owner,”; insisting the team would not eat unless everyone was served, recalled the team's coach, Paul Winters. “;If he sees something that is wrong in his mind, he goes after it,”; Winters said.

Years later, during the Reagan administration, when Olson was asked if the Justice Department could dismiss a prosecutor for being gay, he wrote that it was “;improper to deny employment or to terminate anyone on the basis of sexual conduct.”; In 1984, Olson returned to private practice and was succeeded by Cooper, his adversary in the marriage case. The switch eliminated “;what was seen as a certain libertarian squishiness at the Office of Legal Counsel under Ted,”; Calabresi said.

During the Bush administration, Olson was consulted on a plan to amend the Constitution to define marriage as between a man and a woman. “;What were we thinking putting something like that in the Constitution?”; he recalls telling the White House.

Around that time, state legislatures were debating alternatives to same-sex marriage like civil unions, but Olson said he saw them as political half-measures that continued to treat gay men and lesbians as separate and unequal. Over dinner at a Capitol Hill restaurant, he argued that marriage was an essential component of happiness that gay couples had every right to enjoy, recalled David Frum, a conservative author and former Bush speechwriter.

“;I was really impressed and struck by how important the issue was to him,”; Frum said. “;The majority view at the table was on the other side, but his view was, 'You have to make peace with this because it is sure to happen, and you will see it in your lifetime.”;'

CONFIDENT ADVOCATE

Olson signed on to the California case after a meeting at Reiner's home last December, telling the group gathered there that he would not “;just be some hired gun,”; Schake recalled. In fact, he had already rebuffed a query about defending Proposition 8.

Still, to allay suspicions on the left, he suggested bringing on his adversary in Bush v. Gore, David Boies, whom he had since befriended. Both lawyers agreed to waive part of their fees.

“;I thought, why wouldn't I take this case?”; Olson said. “;Because someone at the Federalist Society thinks I'd be making bad law? I wouldn't be making bad law.”;

In Olson's analysis, the situation in California presents a favorable set of facts for an equal protection argument. Proposition 8 created three classes: straight couples who could marry, gay men and lesbians who had married in the brief period before the ban, and gay couples who wanted to marry but now could not.

As he began honing the arguments, he sounded out a few confidants.

He talked to Robert McConnell, a friend from the Reagan Justice Department. McConnell, a practicing Catholic, said he told Olson that as a religious matter, he believed that marriage ought to be reserved for two people who can procreate. He said Olson replied that while he respected his convictions, he considered it a civil-rights issue.

Olson, who is not a regular churchgoer, began to elaborate on his view that religious beliefs were insufficient legal justification for government to refuse to recognize same-sex marriage, but soon paused. “;You don't agree with me, do you?”; McConnell recalled him saying.

Booth Olson, a Democrat, said she was thrilled that “;on this case we'll be on the same wavelength.”; She said Olson's mother, Yvonne, expressed some initial concern that a court decision overturning Proposition 8 would disenfranchise voters, but came around after Olson explained that voters cannot impose mandates that violate constitutionally protected rights.

In the lawsuit, filed in May, he asserted that Proposition 8 had done just that.

Since then, he and Cooper have been filing dueling briefs.

The Supreme Court has long recognized marriage between men and women as a right, most notably in a 1967 case overturning bans on interracial marriage. Since sexual orientation, unlike race, is not mentioned in the Constitution, the question is whether that right extends to gay men and lesbians.

The answer, in Cooper's view, can be found in a 1970 case, in which the Supreme Court refused to hear an appeal of a lower court ruling that marriage could be limited to men and women. But Olson points to two more recent Supreme Court cases.

The first is a 1996 decision in which six of the nine justices, citing equal protection grounds, struck down an amendment to the Colorado Constitution that stripped gay residents of existing civil rights protections. This, Olson argues, is similar to Proposition 8's negating the California Supreme Court decision that recognized the rights of gay couples to marry.

The second is the court's 6-3 decision in Lawrence v. Texas, striking down laws criminalizing sodomy in 2003. Not only did the majority find that Texas had no rational basis to intrude into private sexual behavior protected by the Constitution's due process clause, it also declared that gay men and lesbians should be free to enter into relationships in their homes and “;still retain their dignity.”;

Cooper asserts that Olson is stretching the scope of the Lawrence decision, pointing out that it dealt with the criminalization of private sexual behavior, not a state's duty to recognize a marriage. But Olson notes that no less a conservative than Justice Antonin Scalia argued in a blistering dissent that the majority in Lawrence had indeed opened the door to same-sex marriage.

Given that the Lawrence case established gay sex as a protected right, Olson argues, the state must demonstrate that it has a rational basis for discriminating against a class of citizens simply for engaging in that behavior.

He dismisses Cooper's contention that the California ban is justified by that state's interest in encouraging relationships that promote procreation and the raising of children by biological parents. If sexual orientation is not a choice — and Olson argues that it is not — then the ban is not going to encourage his clients to enter into heterosexual, child-producing marriages, he insists. Moreover, he says, California has waived the right to make that argument by recognizing domestic partnerships that bestow most benefits of marriage.

And that is if the state wanted to: Olson structured the lawsuit so the named defendants are two proponents of same-sex marriage, Gov. Arnold Schwarzenegger and Attorney General Jerry Brown. Both have filed helpful briefs questioning the constitutionality of Proposition 8. Last month, at a Federalist Society lunch, Olson delivered his annual roundup of the Supreme Court term. He was greeted warmly, but there was palpable discomfort over the marriage case. Not a single person mentioned it to him, save for an oblique ribbing by David Bossie, whom Olson is representing in a case involving his scathing documentary about Hillary Rodham Clinton. After pecking Booth Olson on the cheek, Bossie told her husband, “;I'm not going to kiss you, even though apparently you wouldn't mind.”;

William Bradford Reynolds, another Reagan-era colleague, said later that while Olson presented a thoughtful case, “;He's taking a more assertive view of how one should interpret the Constitution than you would normally expect Ted to take.”;

Olson is confident. Paul Katami, one of the plaintiffs recruited for the lawsuit, recalled Olson's words shortly before it was announced: “;He put his arm around me and said, 'We're going to plan your wedding in a couple of years — this is going to happen.”;'