We play a game where characters in a universe filled with fighting and death and adventures. No matter how real we try and make it, there are certain concepts that will never actually translate well. Characters will never really feel pain. Characters often don't fear death, especially in games where death is not necessarily the end*.
So what is the worst possible thing you could do to punish someone in a world like this?
Banishment.
Really, Banishment should be reserved for the worst of the worst crimes, like Treason or Serial Murder. And yet, I have seen a lot of people throw it around lightly in my years at NERO.
When you banish someone's character, you're telling them that the player can never play that character at your game ever again. In most cases, it ends up being an OOG punishment for IG actions made by the player. And that's fine for certain crimes, as this offers the risk that games with limited death can't offer. You know, "Go Big or Go Home."
So what's the point of this article?
You should only be banishing characters for premeditated and extreme crimes and you should never banish someone for something that's accidental or may not have been clearly illegal.
I remember Galavast, where for a time the PCs had made the punishment for every crime "Death, Banishment, and loss of all possessions." On the surface, it looks like it's just someone trying to prevent crime with harsh punishments. But, in essence, a PC was punishing players OOG for committing crimes by banishing them. That PC was essentially banning players from playing at Galavast for anything, even victimless crimes.
That's a terrible business model.
Now, in some games I've seen a much better punishment that banishment. Characters are permitted to remain, but they are no longer protected by the laws of the land. They lose the security that they once had but they can continue to hang out with their friends and participate in the game, albeit more difficult to stay safe.
So let this be a public service announcement - Banishment is a heavy handed punishment reserved for high risk crimes. PCs should never have the ability to issue banishment, and plot should only ever use banishment for premeditated crimes where the players know the cost of failure.
*Players may fear death, but they don't fear it in the same way as real life. They fear losing their character, but they don't fear the unknown that accompanies death.