AspectJ aims at managing tangled concerns in Java systems. Crosscutting aspect definitions are woven into the Java bytecode at compile-time. Whether the better modularization introduced by aspects is real or just apparent remains unclear. While aspect separation may be useful to focus the programmer's attention on a specific concern, the oblivious nature of the weaving makes it difficult to figure out the behavior of the whole system. In particular, it is not easy to figure out if two aspects interfere one with the other. We built a bytecode slicer called XCutter in order to study which part of the woven code is affected by the application of an aspect. However, our experiments show that a static analysis of AspectJ woven bytecode does not give the expected results, unless the code is properly annotated. Categories and Subject Descriptors