But there is a second case, and there Mr. Verrilli faces tough choices. On March 26, the day before the argument about the 1996 law, the justices will hear Hollingsworth v. Perry, No. 12-144. It seeks to overturn Proposition 8, a voter initiative that banned same-sex marriage in California.
If marriage is a matter for the states, as Mr. Obama announced in May, you might think that California should be permitted to prohibit same-sex marriage.
The federal government is not a party to the California case, and it is not required to file a brief or to take a public position. Ms. Roberts asked Mr. Obama a direct question in May about whether he had given his lawyers instructions about what to do: “Can you ask your Justice Department to join in the litigation in fighting states that are banning same-sex marriage?”
Mr. Obama changed the subject.