As a compromise between unregulated vigilantism and the established committee procedure, how about this?
Any admin has the right to temp-ban a user, BUT:
* Must report this ban to the mailing list of the encyclopedia from which the user is banned * The Arbitration Committee will immediately review the temp-ban
This is like letting any cop arrest a suspect, but requiring a judge to decide that very same day whether to put him in jail pending trial or release him on his own recognizance.
We are working in Internet time. So perhaps the full Arbitration Committee needn't meet to discuss the validity of a temp ban. Maybe only one A.C. member would be enough.
They could say, "Okay, Raul acted in good faith but we think user:Nutso isn't an "emergent threat" so we're overturning the temp ban. Please go through channels on this one."
Or they might say, "Yeah, what a pest! Temp ban sustained pending committee consideration."
Ed Poor, aka Uncle Ed