Partly, it pushed him back 100 hours in his process getting provincial. Measuring hours given his login times makes it very different compared to most, but that is still a substantial setback for someone who was otherwise doing a good job as a Magistrate.

Typically mistakes lead to being knocked back in the city structure (hierarchy? Impossible! All city order is equal!), but it very much depends for me on the circumstances of the mistake, the severity of it, what they did to remedy the situation, and whether or not they fessed up to it.

If they murdered people in a city, depending on how long their good service has been, I could even uninduct them until they end up somehow making up for it.

Otherwise the other posts do make good points in regards to character issues. You might compare it to how it is okay for forties to 'mess up' and kill goodies sometimes (to varying degrees). That isn't to say Magistrates shouldn't be better, but I try to tailor punishments according to the current Provost (they typically get to pick), the character, their history, etc.

Hopefully this answer isn't too lame.

-Ish