The hired gun mechanism

"We present and experimentally test a mechanism that provides a simple, natural, low cost, and realistic solution to the problem of compliance with socially determined efficient actions, such as contributing to a public good. We note that small self-governing organizations often place enforcement in the hands of an appointed leader-the department chair, the building superintendent, the team captain. This hired gun, we show, need only punish the least compliant group member, and then only punish this person enough so that the person would have rather been the second least compliant. We show experimentally this mechanism, despite having very small penalties out of equilibrium, reaches the full compliance equilibrium almost instantly"--National Bureau of Economic Research web site.