http://developers.de/blogs/damir_dobric/archive/2009/02/09/net4-0-code-conditions-implementing-custom-rewriter.aspxRuntime behavior of assertions and assumptions are already defined in the original Contract class. However, their behavior can be modified with the rewriter. My problem is that defined assertions are not designed for real productive use. Application whichenCommunityServer 2008 SP1 (Build: 30619.63)