In President Barack Obama’s latest act in support of gay rights, his administration on Thursday urged the U.S. Supreme Court to allow same-sex marriages to resume in California.

The administration filed a friend-of-the-court brief in a case set to be argued on March 26 on whether California’s 2008 measure, known as Proposition 8, is unlawful under the U.S. Constitution.

In the brief, Solicitor General Donald Verrilli argued that states cannot give all the benefits of marriage to gays and lesbians without calling it marriage.

That position, if adopted by the court, would affect not just California but also seven other states that offer benefits to same-sex couples while barring marriage.

The states allow civil unions or domestic partnerships providing all or virtually all state-level spousal rights but not the “marriage” designation.

They are Delaware, Hawaii, Illinois, New Jersey, Rhode Island, Nevada and Oregon.

Attorney General Eric Holder said in a statement that the filing “seeks to vindicate the defining constitutional ideal of equal treatment under the law.”

Verrilli wrote that the California law “provides to same-sex couples registered as domestic partners all the legal incidents of marriage, but it nonetheless denies them the designation of marriage allowed to their opposite-sex counterparts.”

As a result, “the exclusion of gay and lesbian couples from marriage does not substantially further any important governmental interest,” he said.