Constitutional privilege

I really like this story (true or apocryphal!):

Like every other president, William Howard Taft had to endure his share of abuse. One night at the dinner table, his youngest boy made a disrespectful remark to him. There was a sudden hush. Taft looked thoughtful.

“Well,” said Mrs. Taft, “aren’t you going to punish him?”

“If the remark was addressed to me as his father, he certainly will be punished,” said Taft. “However, if he addressed it to the President of the United States, that is his constitutional privilege.”

I found it here.