The institute of the preliminary ruling procedure is a crucial mechanism for ensuring a uniform interpretation and application of European Union law, enabling national courts to seek guidance from the Court of Justice of the European Union when they believe that a provision is invalid or requires interpretation by the Court of Justice of the EU. In addition to it, the European Court of Human Rights plays a key role in protecting the fundamental rights of individuals in the EU, as do constitutional courts that operate at the national level and safeguard the human rights and freedoms enshrined in the constitutions of member states. Recent case law has revealed different perspectives between the Court of Justice of the EU and the ECtHR regarding the institute of the preliminary ruling procedure, particularly concerning the role of individuals in that procedure. On one hand, individuals have sought protection of their rights through the ECtHR, while on the other hand, they have been ensured protection through the constitutional courts of member states. The aim of this thesis is to provide a comprehensive analysis of the importance and significance of the preliminary ruling procedure in European law through various approaches taken by the courts, namely the Court of Justice of the EU, the ECtHR, and the constitutional courts of member states, with a particular emphasis on the role of the individual in the procedure, as well as the fundamental rights sought to be protected through relevant case law, all in order to ensure a proper interpretation and consistent application of European law.