A Program Logic for Handling Java Card's Transaction Mechanism Bernhard Beckert and Wojciech Mostowski In this paper we extend a program logic for verifying Java Card applications by introducing a "throughout" operator that allows us to prove "strong" invariants. Strong invariants can be used to ensure "rip out" properties of Java Card programs (properties that are to be maintained in case of unexpected termination of the program). Along with introducing the "throughout" operator, we show how to handle the Java Card transaction mechanism (and, thus, conditional assignments) in our logic. We present sequent calculus rules for the extended logic.