Determining environmental impacts of products is complex. In this study, BIO IS, the Institute for European Environmental Policy (IEEP) and the Ecologic Institute investigated approaches for verifying that claims made by companies on the environmental properties of products or their own overall environmental performance are correct. The study was commissioned by the European Commission, DG Environment. The Ecologic Institute contributed an analysis on the law of the World Trade Organziation as far as relevant for related policy measures. The report is available for download.