The case is Krupski v. Costa Crociere, and the issue, put simply, is: when you sue the wrong party by mistake, what happens?
The justices, according to the transcript, were discussing the nature of the mistake, in light of the fact that based on pre-litigation correspondence, the plaintiff possibly knew or should have been aware of the name of the correct party. Suddenly, Justice Stephen Breyer asked Miami lawyer Robert Glazier, who was arguing for the cruise company, "Have you ever driven a car where your wife has said turn left and you have turned right?" The question triggered laughter in the Court.
Glazier, seemingly flustered at first, tried to steer the discussion back to his case, but finally acknowledged that yes, he had. "Did you do it by mistake?" Breyer said. "Yes, of course, you did. It's happened to every human being. There are millions of instances in which people do things by mistake."
Justice Antonin Scalia could not resist getting into the conversation."I think your wife made a mistake. I don't think you made a mistake," Scalia said, apparently directing his comment to Breyer.
Justice Breyer offered a dutiful husband's only possible response: "No, my wife does not make mistakes."
More laughter, then Breyer continued, "I make mistakes, and sometimes I make mistakes knowing all the facts, and so do you and so does everybody else. So I never heard of this thing that you can't make a mistake knowing all the facts."
http://legaltimes.typepad.com/blt/2010/04/justice-breyer-my-wife-is-infallible.html