The episode refers to the sentence pronounced by Pope Leo III:

"Dei non hominum est episcopos iudicare",

that is, bishops can only be judged by God.

Since the face of the Pope is always that of Leo X,
the parallel is with the confirmation, which took place in 1516,
of the Bull of Boniface VIII, which in 1300 established
that only God can judge the head of the Church.