This afternoon the Supreme Court announced that it will hear arguments in both the California case challenging Proposition 8 and in Windsor v. United States, challenging DOMA. Now the question is how will the Court handle these cases. As I explain below, these cases offer the Court an opportunity to return to the question of whether lesbians and gays should be considered a suspect class. A decision on that could be far more important than the substantive policy question about same-sex marriage that most observers are focused on.
Many observers, including myself, expect that the Court will affirm the Second Circuit’s decision in Windsor. This would mean that Section Three of DOMA would be unconstitutional. This decision would not compel states to recognize same-sex marriage. It would merely require the federal government to recognize same-sex marriages from states where they are legal.
The more difficult question is how the Court will handle the Prop 8 case. Some people hope that the Court will issue a broad opinion, settling the question of whether denying same-sex couples access to marriage violates the Federal Constitution. I think it is more likely that the Court will issue a narrow opinion, applicable only to California. The Court could do this in several ways. Most simply, it could affirm the Ninth Circuit, which wrote an opinion on very narrow grounds applicable to the specific factual case in California (where voters revoked access to marriage for only a specific group that previously had that access, while leaving in place access to almost all the other rights and benefits of marriage). The Supreme Court could also hold that the Ninth Circuit wrongly interpreted Romer v. Evans (one of the key precedents underlying the decision), but remand the case to the Ninth Circuit for further consideration. Or the Supreme Court could later decide that it is not going to issue any opinion in the case, leaving the Ninth Circuit opinion standing with no ruling from the Supreme Court.
If my expectations are correct, than the more important question might be what reasoning the Supreme Court uses in upholding Windsor. As I previously blogged about, in Windsor, the Second Circuit became the first federal court of appeals to hold that gays and lesbians are a suspect class. Moreover, in reaching this conclusion, the Second Circuit rejected the immutability inquiry that has previously been a bar to lesbians and gays. Thus, the Supreme Court could use these cases as a vehicle to return to the question of whether sexual orientation should be a suspect classification. When the Court last addressed this question, in Lawrence v. Texas, it did not provide any clear answer. Lawrence, in many ways, suggested that lesbians and gays should be considered a suspect class. However, the ultimate legal reasoning in Lawrence seemed to rely only on rational basis. This confusion has left lower courts and scholars arguing over whether lesbians and gays should be considered a suspect class.
The Second Circuit provided very clear analysis on this suspect classification question in its opinion. It explained why the immutability inquiry was incomplete in assessing which groups we should protect. Because of this, Windsor makes an excellent vehicle for the Supreme Court to return to this question. If the Supreme Court were to affirm this part of the Windsor decision, holding that lesbians and gays are a suspect class, that would be an enormous victory. That would be far more important than the substantive question about same-sex marriage.
Jeffrey Kosbie, J.D., Ph.D. 
I should add, the Supreme Court also granted cert on a standing question in each case. This means that the Court could decide that the parties involved do not have standing (a legal term for having sufficient interest in a case to be able to argue it in Court) and avoid reaching the substantive questions involved.
This is more likely to be an issue in the Prop 8 case. When California refused to defend Proposition 8 in federal court, the lower court allowed the group that put Prop 8 on the ballot to also defend it in court. Thus, the lower court allowed a citizen group to take the traditional role of the state in defending a state law against a federal constitutional challenge. The Supreme Court could decide that only a state has standing to defend a state law in federal court. This would give the Court another way to rule very narrowly in the Prop 8 case.
Most likely, I think the Court will get past the standing question to reach the merits of the challenge, even if it ultimately decides the case on narrow grounds. But I think there is at least a real possibility of the Court ruling on the standing question instead of the merits. In particular, if the Supreme Court affirms the Second Circuit in Windsor, holding that sexual orientation is a suspect classification, I think it would want to avoid the merits of the prop 8 case. In that scenario, I think the Supreme Court would want to let other lower federal courts first apply suspect classification to same-sex marriage, before deciding itself. Thus, in that case, I think the standing question becomes more attractive. (The standing question in the Windsor case involves a more technical legal question about whether there is a real case or controversy when the government agrees with the challenger that the law being challenged should be unconstitutional.)