Self-Governing player systems

[Shaman]

I was thinking of putting this in the regular discussion board but I think it would be better suited here. What do you guys think about self-governing player systems? 
For example, usually if you commit a 'crime' in any MMO like pvp in a non pvp area, steal items or anything similar , it is usually either strictly managed by game code or outright forbidden. What if instead there was a system where if a 'crime' was committed, players in a clan or government acting as local enforcement could fast travel to the offending area and just handle it themselves? could any system like that be feasible at all or would secondary systems need to be in place to make sure it isn't abused?