Authorization specification in object oriented databases is being increasingly investigated recently by many researchers [4,5,7,9,10]. However, most of the work todate suffers from a lack of formal logic semantics to characterize different types of inheritance properties of authorization policies among complex data objects. This paper is to address this issue from a formal logic point of view. In particular, we propose a logic language that has a clear and declarative semantics to specify the structural features of object oriented databases and authorizations associated with complex data objects in databases. Our formalization characterizes the model-theoretic semantics of object oriented databases and authorizations associated with them. A direct advantage of this approach is that we can formally specify and reason about authorizations on data objects without loosing inheritance and abstraction features of object oriented databases.