Book excerpt: This study considers how tax authorities attempt to strike down international tax avoidance structures, in particular those involving the use of conduit and base companies set up by third-country residents for purposes of "treaty shopping" and "EC-Directive shopping". The book focuses on the interaction between provisions and judicially developed doctrines of domestic tax law preventing international tax avoidance on the one hand, and norms of international law, in particular tax treaties and rules of Community law, on the other. It also considers treaty-based anti-avoidance measures such as the "beneficial ownership" requirement and "limitation on benefits" provisions. This part of the study compares and analyses the case law of Australia, Austria, Belgium, Canada, the Czech Republic, Finland, France, Germany, India, the Netherlands, Switzerland, the United Kingdom, and the United States.