While the Senate considers Ms. Kagan's nomination, Judge Vaughn Walker of the United States District Court in San Francisco is deciding how to rule in a major lawsuit challenging Proposition 8, the 2008 ballot initiative that revoked and banned same-sex marriage in California (while leaving the state's marriage-like domestic partner program intact). Judge Walker may declare that the United States Constitution gives gay couples the right to marry -- a decision sure to start a political firestorm (possibly just in time to give the Democrats an additional headache in this year's midterm elections). Whatever he decides is likely to be appealed, presumably up to the court that Ms. Kagan seems likely to join.