“I’m not sure it’s necessary to get into sexual orientation to resolve this case,” he said. “I mean, if Sue loves Joe and Tom loves Joe, Sue can marry him and Tom can’t. And the difference is based upon their different sex. Why isn’t that a straightforward question of sexual discrimination?”…

“This would be a clean, formalistic way for the court to resolve the case,” Andrew Koppelman, a law professor at Northwestern University, said in an interview. “It could just apply existing sex discrimination law.”…

John J. Bursch, a lawyer defending same-sex marriage bans, had two responses in court to the chief justice’s question. First, he said, it is sex discrimination only if the two sexes are treated differently, but the bans place equivalent burdens on men and women.

Ilya Somin, a law professor at George Mason University, wrote on The Volokh Conspiracy, a blog about law, that the problem with this argument “is that, by the same reasoning, laws banning interracial marriage don’t discriminate on the basis of race.”