Although research in AOP is increasing in maturity there remain many unresolved issues. While current AOP languages offer ever-increasing levels of flexibility, they still fail to offer a sufficient discipline of application to ensure that advanced AOP facilities are used safely and appropriately. Researchers have recognised the need to control aspect composition and have started to explore mechanisms to achieve this [2, 3, 4, 5]. In this paper we aim to provide a novel approach to control aspect composition (using AspectJ as reference) and we employ the concept of roles from Role Based Access Control Models [1] to characterise aspects in terms of both their internal behaviour and their external composition. Then, using policies, we express invariants and constraints on the associated advice and pointcuts.