Efficient patent pools

The paper builds a tractable model of patent pools, agreements among patent owners to license sets of their patents. It provides a necessary and sufficient condition for patent pools to enhance welfare and shows that requiring pool members to be able to independently license patents matters if and only if the pool is otherwise welfare reducing. The paper allows patents to differ in importance, asymmetric blocking patterns, and licensors to also be licensees. We undertake some initial exploration of the impact of pools on innovation. The analysis has broader applicability than pools, being relevant to a number of co-marketing arrangements.