A king may
neither judge nor be judged. This refers to later kings, but kings of
Davidic line may judge and therefore be judged, as Resh Lakish explained
“First correct yourself, and then correct others” - only a person who
is subject to correction may correct others.
But why may the other kings not judge or be judged? Because of an
incident that once occurred. A slave of King Yannai killed a person, and
Shimon ben Shetach called King Yannai to court - because of “...and its owner had been warned by
witnesses...” – the king, the owner of the slave, has to be in
court. Yannai came and sat down. Shimon ben Shetach told him to stand
up, but the king said, “I will do as your colleagues will say.” All the
members of the Sanhedrin were looking into the ground. Shimon ben
Shetach said “You are men of thought! May the Master of thoughts exact
retribution from you!” - and they died. The Sages then decreed that a
king may neither judge nor be judged.
Art: El Greco - St Louis, King of France