Colorado became the latest U.S. state to approve civil unions for gay couples, ending a dramatic turnaround in a state where voters banned same-sex marriage in 2006.

The attitude across the country toward gay rights has been shifting toward acceptance, despite many conservatives' insistence that officially recognized unions, especially marriage, should be only between one man and one woman.

The Supreme Court is set to soon hear arguments in two major cases on gay rights, including a challenge to the federal Defense of Marriage Act, which defines marriage as being between one man and one woman, and a challenge to California's ban on gay marriage.

Depending on how broadly the court wants to tailor its decisions, they could affect the status of gay rights in all states.

With Thursday's action, Colorado will join eight U.S. states that have civil unions or similar laws. Nine states and the District of Columbia allow gay marriage. The law takes effect May 1.

Hundreds looked on as Democratic Gov. John Hickenlooper signed the bill, with many chanting "Equal! Equal!"

"There is no excuse that people shouldn't have all the same rights," Hickenlooper told the crowd.

Civil unions grant gay couples rights similar to marriage, including enhanced inheritance and parental rights. People in civil unions also would have the ability to make medical decisions for their partners.

"It means I can change my name finally," said 21-year-old Amber Fuentes, who plans to have a civil union with Yolanda Martinez, 34.

"It's not marriage, but it still gives us a lot of the rights," Martinez said.

A Pew Research Center survey found that 49 percent of Americans favor allowing gays and lesbians to marry legally, and 44 percent are opposed. A decade ago, 58 percent opposed it and a third supported it.

"It's really meaningful. To have the recognition of your love and relationship just like any other relationship by the state is an important both legal and symbolic thing," said Democratic House Speaker Mark Ferrandino, a sponsor of the bill and the first openly gay lawmaker to hold the title of speaker in Colorado.

Most Republicans opposed the bill, saying they would've liked to see religious exemptions to provide legal protections for those opposed to civil unions. Churches are shielded under the new law, but Democrats rejected protections for businesses and adoption agencies, arguing the Republican suggestions were too broad and could provide legal cover to discriminate.

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