AspectJ is a language implementing aspect-oriented programming on top of Java. Besides modification of program flow and state using advice, AspectJ offers language elements to statically modify existing classes by changing their position in the inheritance hierarchy or introducing new members. This can lead to binding interference, i.e. the dynamic lookup of method calls not affected directly by the aspect might change. This paper presents methods allowing programmers to automatically check the impact of introductions and hierarchy modifications on existing programs.