Invited versus Uninvited
Most commonly, a third party intervenes at the request of one or both of the principals. For example, divorcing couples may seek the services of a divorce mediator. Such invited roles are effective for two reasons: First, the invitation to intervene suggests that at least one of the par ties is motivated to address the dispute in question. Second, the invitation makes the third party appropriate, acceptable, and desirable, thereby increasing clout and legitimacy. An example of an uninvited role is a customer in an airport witnessing a conflict between a flight agent and a passenger.