Gay and lesbian advocates had little luck in the 1990s as they lobbied Congress and the White House on same-sex marriage and on serving in the military. This decade, advocates turned to the courts, where they’ve had considerably more success.

Lawsuits challenging state sodomy laws and same-sex marriage bans have come to define the gay rights movement. Two men from Texas, charged with sexual deviance, convinced six justices of the U.S. Supreme Court that their private, consensual sex life was entitled to protection. That decision, in Lawrence v. Texas in 2003, helped motivate four state supreme courts as they cleared the way for same-sex marriage in their states, beginning with Massachusetts in 2004.

What followed was a methodical, strategic march, led by groups such as Lambda Legal, that organized legal challenges nationwide. A six-year case in Iowa ended this year, when that state’s highest court overturned a law limiting marriage to a man and a woman.

But the opposition ramped up, too, and the results of the marriage lawsuits have been fragile. Since 2004, voters in 26 states have amended their state constitutions to ban same-sex marriage. In one of those, California, the state supreme court had previously ruled in favor of same-sex marriage.

Top appellate lawyers have taken on the issue. Paul Smith, head of the Supreme Court practice at Jenner & Block in Washington, argued Lawrence for the two men. In California, the dispute has moved into federal court and split two leaders of the conservative legal movement: Charles Cooper, name partner at Washington’s Cooper & Kirk, is arguing to uphold the voter-approved ban, while former solicitor general Theodore Olson, co-chair of the appellate practice at Gibson, Dunn & Crutcher, surprised fellow Republicans by working on the side of gays and lesbians. David Boies, a prominent Democrat and name partner at Boies, Schiller & Flexner, is working with Olson.

As the decade draws to a close, the battleground is shifting back to the legislative arena. This year, Congress extended hate-crimes protections to gays and lesbians, and Democrats are planning to push legislation in 2010 that would prohibit workplace discrimination based on sexual orientation.

— David Ingram