The European Commission has proposed including shipping in the European Emissions Trading Scheme (ETS). Ships could, in principle, circumvent the scheme by changing their routes or changing the routes of their cargo. This report presents a number of case studies in order to assess the likelihood of circumvention and any resulting impact on shipping and activities at European ports. The case studies show that circumventing the EU ETS by changing the order of ports or calling at an additional port is sometimes profitable and can therefore not be ruled out. However, we also conclude that the impact of this circumvention on European seaports is likely to be limited. This is firstly because all cargo destined for the EU will still need to be unloaded at European seaports. The circumvention will therefore mostly affect transhipment activities at European seaports. Secondly, operational constraints or capacity limits in non-EU ports could further reduce the risk in the short term.