Advocates of gay marriage seem to have the upper hand after two days of arguments over the issue at the Supreme Court. At the same time, legal subtleties about the justice’s authority in the case may prevent an expansive ruling:

A majority of the Supreme Court on Wednesday questioned the constitutionality of the 1996 Defense of Marriage Act and whether it created unequal classes of married couples by extending federal benefits only to marriages between a man and a woman....

But before the justices decide the merits of the DOMA challenge, they must decide whether the case is properly before them.

They heard about an hour of debate on that point because of the complicated manner in which the case arrives at the court.

The Post’s Chris Cillizza hosts the final Google Hangout on marriage in America. He is joined a group of legal experts, including The Post’s SCOTUS reporter Bob Barnes to break down the arguements behind the Prop. 8 and DOMA cases. (The Washington Post)

The case began with Edie Windsor, the plaintiff, who was forced to pay more than $360,000 in taxes when her wife, Thea Spyer, died in 2009. Manuel Roig-Franzia recounts their engagement in 1967 in a profile:

She dropped to a knee, but Edie was spouting, “Yes, yes, yes” before Thea could finish asking the question. “We were really very much in love,” Edie, now 83, says in an interview, her delight about that moment undiminished by the passage of more than four decades.

Since that time, public opinion on the question of gay marriage has changed considerably, especially in the past few years. The shift has forced political leaders to adapt, writes Dan Balz:

There is no better reminder of how rapidly things have changed than to recall that President Obama declared his support for same-sex marriage just in May — and only after Vice President Biden got there first. . .

Politicians in both parties are scrambling to come to terms with the swift change in public opinion and how that fits with the views of their traditional constituencies.

The change has presented a particular problem for the Republican Party, which has hesitated to oppose gay marriage publicly even as counsel appointed by House Speaker John Boehner (R-Ohio) defend the Defense of Marriage Act in court. Greg Sargent notes the contradiction:

Republicans know they have a problem on their hands when it comes to the rapid evolution on marriage equality and their party’s failure to keep up with it, yet they appear to be constrained from doing anything about it. . . Polls are showing a generational divide among Republicans over this issue; while majorities of Republicans overall continue to oppose gay marriage, pluralities or even majorities of young Republicans now support it.

Democrats have also been struggling to keep up with public opinion, with the party’s legislators declaring their support for gay marriage in droves:

“After much thought and prayer, I have come to my own personal conclusion that we shouldn’t tell people who they can love or who they can marry,” Sen. Kay Hagan (D-N.C.) said Wednesday in a statement posted on her Facebook page.

A day before, Sen. Jon Tester (Mont.) had announced his own change of heart. A day before that, it was Sen. Mark R. Warner (Va.). A day before that, Sen. Claire McCaskill (Mo.) posted her announcement on a Tumblr page, above a frittata recipe.

Dana Milbank argues that in the context of the public’s shift in perspective, the court’s decision may matter little in the long run:

In the case the justices are hearing Wednesday, it is widely expected that they’ll strike down the discriminatory Defense of Marriage Act, which allows states to ignore other states’ same-sex unions. In Tuesday’s case, justices appeared to be looking for a narrow way to rule — something that would apply to Proposition 8 and nothing else.

But nothing the justices do will stop the legalization of gay marriage. . . The question is whether the court forces gay-marriage activists to win the right state by state.

One reason support for gay marriage has spread so quickly is that the issue affects rich and poor alike, argues Matt Miller:

When every economic and social class shares in the experience of injustice or intolerable wrongs, things change faster.If only poor people were gay, does anyone think our political leaders would have “evolved” at this pace? Likewise, if we had a draft, does anyone think our wars in Iraq and Afghanistan would have proceeded as they did?

Like the rest of the country, researchers and social scientists have also grown more accustomed to the idea of gay marriage. One of the major objections to legal same-sex unions has been about child-rearing, but research suggests that concern is unfounded:

There is a growing consensus among experts that the sexual orientation of parents is not a major determinant in how well children fare in school, on cognitive tests and in terms of their emotional development. What matters more, researchers found, is the quality of parenting and the family’s economic well-being.

Pointing to this body of research, Ezra Klein insists that adoption by a gay couple is clearly better than a childhood in foster care:

The idea that there is something so wrong with same-sex households that it would be preferable for these children to go two or four or six years without permanent parents — an idea, again, that has little to no evidence behind it, and that is in fact contradicted by most of the evidence — bespeaks a homophobia so deep that it is hard for me to believe it could persist long among people who actually know any children in the foster system, and who actually know many gay couples.

For comic relief, read these column by Richard Cohen, who discusses the argument that procreation is the purpose of marriage.

Scalia himself was the court’s numero uno procreator, having sired nine children and all the time living in New York and Washington, urban areas literally saturated with homosexual men and women and, unknown to him, transgendered persons, some of color.

And check out the column by Alexandra Petri, who responds to Justice Ruth Bader Ginsburg question whether the act creates a separate, “skim-milk” class of marriages:

This doesn’t even get into chocolate-milk (both the regular kind and the kind you make with Nesquik) marriage, almond-milk marriage and soy-milk marriage, which never expires but it’s never the kind you would buy anyway. And then there’s evaporated-milk marriage. . .

Finally, Wonkblog has excerpts of Tuesday’s arguments, Wednesday’s arguments, and a summary of the legal issues in yesterday’s case. Read a complete retrospective from The Fix here.