The principle of effective judicial protection ('PEJP') is specifically provided for in the EU Charter of Fundamental Rights Article 47. But how effective is the provision and the protection it affords? This ambitious, innovative project examines that question over two volumes. In the first volume an expert team explores how the Court of Justice of the European Union (CJEU) has interpreted the PEJP, as expressed in particular by Article 47, in selected policy areas, and reflects on the impact of the principle on the EU's constitutional structure. Taking both a horizontal interpretation, analysing the constitutional themes in play, and a vertical one, which looks at the Court's interpretation in specific policy areas, it shows the interplay of the protection within the wider architecture of the EU. Addressing key questions such as legal certainty, judicial autonomy and division of competences, it significantly adds to our understanding of judicial protection within the EU.