摘要:The principle of effectiveness is an unwritten principle of European Economic Area law (EEA). It is required by the general principle of homogeneity with European Union law (Article 1(1) EEA Agreement) and the loyalty principle (Art. 3 EEA Agreement). This study explores how this concept has been applied in practice by the EFTA Court within the framework of this legal order during 2010-2020. This European Court has confirmed the existence of the principle as inherent in the EEA Agreement and mostly refers to effectiveness in three different strands of jurisprudence (where effectiveness takes different meanings). The findings of the study show that, while the Court has used the doctrine to guarantee the judicial protection and justiciability of individual rights; it has not defined, clarified or elaborated on the meaning, content and scope of this important principle, A table of most important case-law of the EFTA Court on effectiveness and its different meanings is to be found in the conclusions.