I think a system setup by the events team(?) for bank robberies could work, but it would need tight rules and restrictions on it to ensure that the experience itself is fair, fun and not confusing.
Rough idea of a couple of restrictions that could be used:
A detailed and thorough plan for the robbery - all the details of the plan must be prepared in-game and done in-character.
Admin approval of the robbery is a must - the organizers of the crime would have lengthy discussion with the head of events, in order to ensure that the plan itself is sound and doesn't violate any server rules and keeps in the spirit of making sure the event would be fair, fun and not confusing.
Upon admin approval, a time could be set in which the robbery would take place. The event would have to take place during a time in which there would be plenty of PD members online.
Upon entering the bank, once the first weapon is drawn the PD would be notified of the on-going robbery and would dispatch as soon as possible.
The event would be watched and supervised by an admin (or a group of admins).
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Bank robberies would only be allowed to be done by long term players who have a good standing within the community and who have a good grasp of the server rules. Robberies themselves would only be allowed to be done once is a blue moon.