In the 136-page decision (an additional source of the ruling is HERE), Judge Walker ruled that Proposition 8 violated the U.S. Constitution's clauses regarding equal protection and due process rights. The judge claimed that Proposition 8 both unconstitutionally burdens the exercise of the fundamental right to marry and creates an irrational classification on the basis of sexual orientation. The judge also concluded that Proposition 8 fails to advance any rational basis in singling out gay men and lesbians for denial of a marriage license, stating that the evidence shows Proposition 8 does nothing more than enshrine in the California Constitution the notion that opposite-sex couples are superior to same-sex couples. Because Proposition 8 in Judge Walker's mind prevents California from fulfilling its constitutional obligation to provide marriages on an equal basis, the court concludes that Proposition 8 is unconstitutional.
The Church of Jesus Christ of Latter-day Saints, which, along with Roman Catholics and several evangelical groups, spearheaded the religious opposition to gay marriage, has issued a statement decrying the decision, although they continue to call for mutual respect and civility on both sides:
"The Church of Jesus Christ of Latter-day Saints regrets today's decision. California voters have twice been given the opportunity to vote on the definition of marriage in their state and both times have determined that marriage should be recognized as only between a man and a woman. We agree. Marriage between a man and woman is the bedrock of society.
"We recognize that this decision represents only the opening of a vigorous debate in the courts over the rights of the people to define and protect this most fundamental institution—marriage.
"There is no doubt that today's ruling will add to the marriage debate in this country, and we urge people on all sides of this issue to act in a spirit of mutual respect and civility toward those with a different opinion."
Proponents of Proposition 8 do not intend to take this decision lying down. They are expected to appeal the ruling to the U.S. 9th Circuit Court of Appeals and then up to the U.S. Supreme Court if necessary. According to a comment posted on FaithPromotingRumor, there are four full-time LDS judges on the Ninth Circuit; Judges Richard Paez, Jay Bybee, Milan Smith, and Randy Smith. J Clifford Wallace is also LDS and is on Senior Status(semi-retired). This means is that there is a chance that an LDS judge will be on the three judge panel. If the case is heard en banc,an LDS judge will almost certainly be on the 11-judge panel. Any LDS judge on the panel may come under pressure to recuse himself, although if a gay judge didn't recuse himself, there's no need for an LDS judge to recuse himself, either.
The Heritage Foundation sharply condemned Judge Walker's history of judicial activism in this Orange County Register column.
Wikipedia provides more background about Judge Vaughn Walker. He was first nominated to the Federal bench by Ronald Reagan in 1987. Renewed by George H.W. Bush in 1989, he was then confirmed by the U.S. Senate in 1989. The real kicker is that Judge Walker is openly gay.
Imagine that -- a gay judge striking down a law forbidding gay marriage freely voted on by a majority of the people. Can you say "conflict of interest"?