This book is based on a report submitted to the European Parliament, whose aim was to provide a comparative analysis of legal provisions, doctrine and case-law on locus standi before civil, administrative and criminal courts of some selected legal systems and before the EU courts. Apart from the EU legal system, the study focuses on the legal systems of nine Member States of the European Union (Belgium; England and Wales; France; Germany; Hungary; Italy; Netherlands; Poland; Sweden) and the legal system of one non-EU Member State (Turkey). On the basis of the findings, a conclusive chapter stresses the congruities and differences between the legal standing criteria in the Member States, on the one hand, and before the EU Courts, on the other. Moreover, the findings with regard to the different fields of law in the Member States are compared. On the basis of a thorough analysis of the status quo in the EU and Member States' legal systems, recommendations have also been developed, including suggestions on the possible improvements to the standing requirements in the EU and national legal systems.