The principle of subsidiarity in the European Union within the framework of multi-level governance approach

The European Union (EU) is a supranational organization defined by its multi-level governance structure beyond the borders of the nation-state. One of the theoretical frameworks developed to understand and explain the functioning of this structure, the Multi-Level Governance (MLG), provides an effective tool for analyzing the complex decision-making processes of the EU. This theory is a governance system based on the joint production of policies by local, national and supranational actors in the EU integration process. One of the issues at the center of the multi-level governance structure is the principle of subsidiarity. The principle of subsidiarity, which has an active place in the management of many international organizations and nation states, has become a general principle of EU law, especially since 1992, and has played an important role in the functioning of the union. In the European Union, which has a multi-level and participatory governance structure, local and regional governments have an important role in the decision-making and policy-making processes of the union. According to the principle of subsidiarity, before a decision is taken by the EU central government, it is necessary to assess whether the relevant policy can be effectively implemented by member states or lower administrative units. The principle of subsidiarity is a fundamental principle in the EU's decision-making processes and advocates that central governments should not interfere with the functioning of local governments in member states and can only intervene in issues that can be resolved more effectively at the local or regional level. This principle is not only a technical aspect of the distribution of authority within the union, but also plays a central role in terms of the democratic legitimacy, accountability and effectiveness of the European Union. In this study, the place and function of the principle of subsidiarity within the institutional structure of the European Union is examined in the context of the Multi-Level Governance approach. In the study, it has been determined that the principle of subsidiarity, which has a multi-level governance structure and is a part of the legal basis of the EU with the Maastricht Treaty adopted in 1991, is quite effective on the European Union and its member states; however, it is one of the most controversial concepts in EU Law and requires various changes.With the progress and deepening of the integration process of the union, the distinguishing feature of which is based on the "transfer of sovereignty", it has been seen that the member states need to transfer their sovereignty to the central government in many areas, but at the same time they want to protect their own sovereignty. At this point, it has been understood that the principle of subsidiarity constitutes a bridge in terms of trust between the member states, EU citizens and the union. As a result, within the multi-level governance structure, it is seen that the principle of subsidiarity has the potential to increase democratic legitimacy and governance effectiveness within the European Union and will exist in the future of the EU. However, the realization of this potential will be possible by adopting a more transparent, participatory and accountable governance approach supported by institutional reforms. From this perspective, the principle of subsidiarity has a strategic importance in shaping the EU's future governance vision, and the principle's future effectiveness and role in the EU will be determined by the new policies to be put forward and the future inter-institutional structure of the union. Keywords: European Union, Integration Process, Multi-Level Governance, Subsidiarity Principle, Local and Regional Governments.