U.S. District Court Judge Vaughn Walker ruled Wednesday that California’s ballot measure banning same-sex marriage violates the federal constitution’s guarantees to equal protection and due process of law. A few minutes after issuing the decision, Walker also issued a temporary stay of its impact and directed attorneys challenging the initiative to respond to request by August 6.

The 136-page decision, which has been much anticipated by both sides of the same-sex marriage debate, says supporters of Proposition 8 failed to establish any rational or legitimate reason for prohibiting same-sex couples from having marriage licenses.

Judge Walker, an appointee of Republican President George H.W. Bush, applied simple rational basis review in making his decision. He said that, “Even if California had an interest in preferring opposite-sex parents to same-sex parents …Proposition 8 is not rationally related to that interest, because Proposition 8 does not affect who can or should become a parent under California law.”

“This is a tour de force—a grand slam on every count,” said Shannon Minter, an attorney with the National Center for Lesbian Rights. “The court held that Prop 8 violates the fundamental right to marry and discriminates on the basis of both sex and sexual orientation in violation of the equal protection clause.”

“The court,” said Minter, “held that laws that discriminate based on sexual orientation must be subject to the highest level of constitutional review, but that Prop 8 would fail even the lowest test, because it is based solely on moral disapproval of gay people. The court made detailed findings of fact about all of the evidence presented and the credibility of the witnesses.

“This is without a doubt a game-changing ruling,” said Minter. “Today’s decision is the most comprehensive, detailed decision addressing the constitutional rights of same-sex couples to affirmative recognition and support ever to be issued by a federal court.”

The opinion represents the first major victory for legal challenges against state bans on same-sex marriage in federal court. Two other state-related cases in federal courts have been dismissed. Two federal cases challenging part of the federal Defense of Marriage Act (DOMA) won a critical district court victory last month in Boston and are expected to be appealed to the 1st Circuit U.S. Court of Appeals. All three of these cases are expected to eventually reach the U.S. Supreme Court and are on track to arrive at approximately the same time.

Yes on 8 attorneys filed a motion with Judge Walker on Tuesday night, asking that, if the court rules against them, to issue a stay of the impact of his decision pending their expected appeal to the 9th Circuit U.S. Court of Appeals. Walker, thus far, has not responded to that request.

Meanwhile, pre-planned rallies to celebrate –or protest-- Wednesday’s ruling are scheduled to take place in major cities across the country Wednesday evening. Rallies are planned in a number of major cities around the country following release of the decision –including New York (7 p.m. NYC Supreme Court), Boston (6 p.m. Copley Square), West Hollywood (6 p.m. West Hollywood Park), Dallas (6 p.m. at Legacy of Love Monument), Atlanta (7 p.m. 10th and Piedmont) and San Diego (6 p.m. LGBT Community Center).

Walker heard testimony for three weeks in January and closing arguments in June. The legal team challenging Proposition 8 was led by two of the country’s most prominent and respected attorneys –conservative Ted Olson and liberal David Boies. The challenge was organized and funded by the newly formed Americans Foundation for Equal Rights, headed by Democratic activist Chad Griffin.

Conservative attorney Ted Olson, who along with liberal attorney David Boies, led the challenge against Proposition 8 are holding a press conference in San Francisco now.