Ad Hoc LAN systems are noncooperative MAC settings where regular stations are prone to "bandwidth stealing" by greedy ones. The paper formulates a minimum-information model of a LAN populated by mutually impenetrable groups. A framework for a noncooperative setting and suitable MAC protocol is proposed, introducing the notions of verifiability, feedback compatibility and incentive compatibility. For Random Token MAC protocols based on voluntary deferment of packet transmissions, a family of winner policies called RT/ECD-
is presented that guarantees regular stations a close-to-fair bandwidth share under heavy load. The proposed policies make it hard for greedy stations to select short deferments, therefore they resort to smarter strategies, and the winner policy should leave the regular stations the possibility of adopting a regular strategy that holds its own against any greedy strategy. We have formalized this idea by requiring evolutionary stability and high guaranteed regular bandwidth shares within a set of heuristic strategies.