One school of thought was that the court’s four liberals were ready to try to capture Justice Kennedy’s decisive vote to establish a right to same-sex marriage around the nation.

That theory was demolished in the courtroom as one liberal justice after another sought to find a way to avoid providing an answer to the central question in the case. The decision to hear the case, it turned out, had come from the other side.

Justice Scalia, almost certainly joined by Justices Clarence Thomas and Samuel A. Alito Jr., apparently made a twofold calculation: that their odds of winning would not improve as same-sex marriage grows more popular and more commonplace, and that Justice Kennedy, who is likely to write the decision in the case concerning the 1996 law, would lock himself into rhetoric and logic that would compel him to vote for a constitutional right to same-sex marriage in a later case…

That leaves the question of the fourth vote. The most likely answer is that it was that of Chief Justice John G. Roberts Jr., though he did not sound at all pleased on Tuesday to have the case before him.

There is also a chance that the fourth vote came from Justice Kennedy himself, and his very questioning provides support for that theory.