This paper provides an experience report on the use of aspect-oriented technology as a means to modularize the implementation of business rules in an object-oriented, large scale case study. The goal of this refactoring of the system was to provide a proof-of-concept implementation of how such an aspect-oriented solution can improve the modularity and the extensibility of the business rule implementation. This paper focusses on the approach taken in refactoring the system and the difficulties of integrating the aspect solution into the build process.