Sen. Barbara BoxerBarbara BoxerAnother day, another dollar for retirement advice rip-offs Carly Fiorina 'certainly looking at' Virginia Senate run Top Obama adviser signs with Hollywood talent agency: report MORE (D-Calif.) said the California Supreme Court's ruling to uphold Proposition 8 on Tuesday is sending the state in the wrong direction on civil rights.

"Unfortunately, with this decision, I am concerned that we are back to square one on the issue of equal rights for same-sex couples," Boxer said in a statement.

Boxer also criticized the court's ruling that bans same-sex marriage going forward but continues to recognize the marriages of the 18,000 same-sex couples who have already been married.

"This ruling sets up a very unfair reality in California where some same-sex couples will have their marriages affirmed, while many more will be denied their fundamental rights," she said.