Judge Walker’s fervent ideological bias in favor of same-sex marriage has been clear from the outset of the anti-Prop 8 case, and more recent reports that he is gay and has a same-sex partner have merely added some possible explanatory detail. As law professor (and Bench Memos contributor) Gerard Bradley explains in this essay (emphasis added), the very manner in which Walker wrote his opinion reveals his bias:

We can now look at Judge Walker’s opinion and ask: is this the handiwork of an impartial and open mind on the subject of same-sex marriage?
Or does the opinion rather resemble an ad hoc rationale for conclusions reached by its author – Judge Walker – on other grounds?
You do not have to be a legal expert to conduct this experiment. You can even try it at home. Slog through Judge Walker’s 136-page opinion and then ask yourself: why does this document read like the battle report of a search-and-destroy mission?
One would think, for example, that there are some rational bases for saying that marriage is what our society and our law have understood it to be for a few hundred years: the union of a man and a woman. Not in Judge Walker’s court.
One might think, too, that some (and perhaps a lot) of what the plaintiffs’ “expert” witnesses against traditional marriage would be branded by a fair-minded judge as the fruit of passionate political advocacy, and not dispassionate scholarly analysis? Not in Judge Walker’s court.
Read the opinion and you will see that, when it comes to the defense witnesses in favor of Proposition 8, Judge Walker takes no prisoners, gives no quarter, shows no tender mercies.
He portrays those who supported traditional marriage in the Proposition 8 fight as not only wrong. They are wrong in every decisive respect, and utterly so.
But their position is not only utterly wrong. It lacks any basis in reason.…
Now, one standard test of impartiality is fairness, and even a certain sympathy, in stating an opponent’s position and in explaining the evidence and arguments for it. This is simply what an honest search for the truth entails. Even allowing for the rough-and-tumble of litigation, Judge Walker flunks this test.
On the other hand: Judge Walker credited the plaintiffs’ witnesses across the board, and deemed almost everything of consequence that they said to be true.…
The plaintiff’s witnesses’ uncanny accuracy is all the more surprising, for they were not exactly non-partisan technocrats. They are leading scholar-activists in the culture war over same-sex marriage.
Several are conspicuously passionate about the injustice of traditional marriage. Some even contributed money to the anti-Proposition 8 Campaign.
That these witnesses had a shared passionate commitment to same-sex marriage does not mean that their testimony was flawed (although I do think it was flawed, in many important respects).
Their evident partisanship does not even mean that they were unqualified to be expert witnesses. It does mean, however, that an impartial judge would be keen to subject their testimony to searching critical evaluation, lest their “private morality” (to use Judge Walker’s description of the traditionalists’ beliefs about the nature of marriage) color their public testimony. On my reading of Wednesday’s opinion, Judge Walker flunks this test too.