Gay rights group Lambda Legal filed its promised lawsuit to win gay marriage in New Jersey Thursday.

“The New Jersey Supreme Court ordered equality for same-sex couples when it decided our marriage lawsuit in 2006, and the legislature has failed to meet that crystal-clear obligation,” Hayley Gorenberg, deputy legal director of the group, said in a statement. “Civil unions are a failed legislative experiment in providing equality in New Jersey – marriage equality is the only solution.”

An optimistic Steven Goldstein, CEO of Garden State Equality, New Jersey's largest gay advocate, told “We've lived the agony of defeat. Now it's time for the thrill of victory.”

The challenge comes after senators killed a gay marriage bill in January. The defeat means that the Legislature isn't likely to revisit the issue over the next four years as Governor Chris Christie, a Republican who took the helm in January, does not support giving gay couples the right to marry.

In Lewis v. Harris, the New Jersey Supreme Court unanimously agreed that it is unconstitutional to deny gay and lesbian couples the rights granted to married heterosexual couples and ordered the Legislature to remedy the situation. Lawmakers responded with a civil unions law.

Lambda Legal is representing six gay and lesbian couples plus the surviving spouse from a seventh in its challenge. The lawsuit claims civil unions are not equal to marriage.

“After the court decision, we hoped that our civil union would provide much of the security we had been seeking, but we have learned that too often, that is not the case,” plaintiffs Mark Lewis and Dennis Winslow said. “Even the acceptance we experience is completely arbitrary and dependent on individuals' attitudes toward us. It's the difference between rights and luck.”

Activists announced they would return to court the day after senators voted down the gay marriage bill.