The two took time during the third day of Senate Judiciary Committee hearings Wednesday to parry about the TV attorney played by Raymond Burr who won all but one case.
But what was that one case? Both Franken and Sotomayor drew a blank.
Sotomayor said she watched "Perry Mason" as a child, and was inspired by the show to pursue a law career.
After quizzing Sotomayor about judicial deference to Congress and judicial activism, Franken concluded his questioning by asking Sotomayor if she remembered which case Mason lost.
"I wish I remembered the name of the episode, but I don't," she said.
"Didn't the White House prepare you for that?" Franken asked.
Even Committee Chairman Patrick Leahy got into the act, asking Franken if he knew which episode it was.
"I don't know. That's why I was asking," Franken said. "If I knew, I wouldn't have asked her."
"All right," Leahy said, "Well ... because of that, Judge, we will not hold your inability to answer the question against you."
CNN later reported that the fictional Mason actually lost three cases during the series.