Separation of concerns has long been an important strategy in the software systems development to cope with the complexity embedded in such systems. The same type of concerns, like security concerns, is often repeated in many modules of a system, which hinders the consistency, re-usability, change and maintenance of the system. Aspect orientation aims to separate and encapsulate these concerns to solve the complexity problem. This paper introduces the use of aspect orientation for case and adaptive case management through changing the rules that govern business processes on the fly. It introduces a taxonomy of such rules based on the declarative workflows approach. It also shows how so-called form-based case management systems could be extended to support aspect orientation to reduce the complexity problem. This work is presented in Adaptive Case management and other non-workflow approaches to BPM in Ulm, Germany, 2014