Misbehavior in mobile ad-hoc networks occurs for several reasons. Selfish nodes misbehave to save power or to improve their access to service relative to others. Malicious intentions result in misbehavior as exemplified by denial of service attacks. Faulty nodes simply misbehave accidentally. Regardless of the motivation for misbehavior its impact on the mobile ad-hoc network proves to be detrimental, decreasing the performance and the fairness of the network, and in the extreme case, resulting in a non-functional network. Countermeasures to prevent or to combat misbehavior have been proposed, such as payment schemes for network services, secure routing protocols, intrusion detection and reputation systems to detect and isolate misbehaved nodes. We discuss the trade-offs and issues of self-policing mobile ad-hoc networks and give an overview of the state of the art, discussing and contrasting several solution proposals.