With a reference to Franklin Roosevelt's attorney general, Robert Jackson, whose "tenure was replete with challenges," Rosenstein landed another veiled jab.
"One of the difficulties Jackson faced was what he called the 'unpleasant duty' of responding to congressional inquiries," he said, grinning as he paused for a full beat that was filled with laughter and applause from the crowd of lawyers.
Rosenstein, a lifelong Republican, has become an unlikely hero of the left as he's parried with conservative lawmakers and defended the integrity of the Robert Mueller special counsel investigation, which he oversees.