On Thursday, Colorado Gov. John Hickenlooper signed legislation allowing same-sex civil unions in the state; the law goes into effect on May 1.

According to the Denver Post, two of SB 11's sponsors — Rep. Mark Ferrandino and Sen. Pat Steadman — introduced civil measures for three consecutive years that died. "I'm incredibly proud of our state and this historic accomplishment," Steadman said in a statement. However, he noted that a provision in the Colorado Constitution still prevents same-sex marriage. "Some day soon it too must be overturned." He also wrote a poem to commemorate passage of the bill.

Colorado becomes the sixth state to permit civil unions, according to the National Conference of State Legislatures. Nine states — Washington, Vermont, New York, New Hampshire, Massachusetts, Maryland, Maine, Iowa and Connecticut — allow same-sex marriage. Vermont, New Hampshire and Connecticut had passed legislation allowing civil unions, but then adopted same-sex marriage statuses. Three states have adopted broad domestic partnerships available to all unmarried couples; three states and Washington, D.C., provide limited domestic partnerships that include same-sex couples.

On Tuesday and Wednesday, the Supreme Court will hear two cases related to marriage equality. It will listen to arguments regarding California's Proposition 8, which bans same-sex marriage in the state, and the Defense of Marriage Act, which limits marriage to a man and a woman for federal purposes, including benefits for government employees.