Banishment

“You are banished from Camelot. If you ever return, you will pay for it with your life. You have until dawn to leave the city.”
— Uther to Gwaine^[src]

Banishment (also called Exile) is when someone is sent away from a kingdom or country as an official punishment. They are usually barred from returning under pain of death.

Breaking the Knight's Code or the First Code of Camelot are among the offenses that can result in banishment.

List of Banishments

Exile	Offense	Photo
Guinevere Pendragon	Discovered to be in a secret relationship with Arthur Pendragon. Pardoned by Uther Pendragon after Dragoon the Great claimed to have enchanted her. Caught kissing Lancelot the night before her wedding to Arthur. Pardoned by Arthur after the Second Fall of Camelot.
Gwaine	Broke the Knight's Code by fighting Sir Oswald and Sir Ethan in defense of Merlin. Pardoned by Arthur Pendragon after the Fall of Camelot.
Lancelot	Broke the First Code of Camelot by posing as a nobleman to become a Knight. Pardoned by Uther Pendragon after he killed the Griffin.