Gay couples challenge same-sex marriage ban in court (Reuters) - Eight same-sex couples have filed suit in U.S. federal court challenging Nevada's gay marriage ban as unconstitutional and saying the state's domestic-partnership statute relegates them to second-class status. The lawsuit came two months after a U.S. appeals court struck down a similar voter-passed ban on same-sex matrimony next door in California, marking one of several victories by gay-marriage advocates on various legal and legislative fronts this year. Nevada's voters approved a state constitutional amendment in back-to-back elections in 2000 and 2002 barring same-sex marriage, establishing that "only a marriage between a male and a female person shall be recognized and given effect." The state legislature later enacted a separate law in 2009 bestowing substantially the same rights, protections and benefits of marriage on gay and lesbian couples who registered as domestic partners. But the court challenge brought on Tuesday called Nevada's marriage ban and parallel "second-class" legal status for gay couples discriminatory and a violation of their rights to due process and equal protection under the U.S. Constitution. The two-tiered system, it said, "serves no purpose other than to impose a stigmatizing government label of inferiority upon lesbians and gay men and their relationships, and denies plaintiffs equal treatment based on their sexual orientation and sex." The lead plaintiffs, Beverly Sevcik, 73, and Mary Baranovich, 76, of Carson City, said in a statement that they had been a committed couple since 1971, raising three children together. They now have four grandchildren. We've been together for almost 41 years. We've seen each other through thick and thin, in sickness and in health," Sevcik said. After four decades of sharing a life together, all we want is to show our love for each other as other couples do, through marriage. The suit names Republican Governor Brian Sandoval and several local and county officials as defendants. A spokeswoman for Sandoval declined comment, and a representative for the state attorney general could not immediately be reached. The suit was brought on the couples' behalf by the Lambda Legal Defense and Education Fund. Thousands of couples have registered for domestic partnership in Nevada, "and we know there are thousands more who want to marry and don't want to accept second-class status," Lambda staff attorney Peter Renn told Reuters. They don't want crumbs of equality. They want the whole loaf, just like other couples get. Just six states currently recognize gay matrimony -- New York, Massachusetts, Connecticut, Vermont, New Hampshire and Iowa -- as does the District of Columbia. A bid to repeal New Hampshire's gay marriage law was easily defeated last month. Washington state and Maryland earlier this year approved gay marriage, but those statutes have yet to take effect. New Jersey's legislature embraced same-sex marriage, but Republican Governor Chris Christie vetoed that bill. In California, a federal judge ruled that state's same-sex marriage ban as unconstitutional in a ruling upheld in February of this year by the 9th U.S. Circuit Court of Appeals. Legal experts said that ruling was narrowly tailored to California, where gay marriage was briefly legalized by the state Supreme Court before a state constitutional amendment outlawing it was approved by voters in a ballot measure. Reporting by Steve Gorman in Los Angeles; Editing by Cynthia Johnston and Lisa Shumaker