Croatian membership in the EU is subject to the fulfilment of the legal and political obligations laid down in, among other places, the SAA, the Stability and Association Agreement. The implementation of the SAA depends on the definition of its position in the constitutional system of the Republic of Croatia, including the ability for its provisions to be directly applied in EU and in Croatian courts, the legal status of the bodies provided for in the SAA, and the legal position and legal standing of the decisions taken by these bodies. The implementation of constitutional changes is necessary for full membership of the EU, and some changes are also necessary even for implementation of the SAA. These are provisions that provide the legal basis for membership in the EU, including the definition of the manner of making use of state sovereignty, provisions that define in detail the legal status of international law and European primary and secondary law in the internal legal system of the EU, and provisions that adapt the constitutional organisation of the Republic of Croatia to the conditions of associate or full membership of the EU, optimise the functions of the institutions of state authority that will have to work in new conditions. In an evaluation of the fulfilment of the conditions for membership in the EU, the criterion for evaluation of the extent to which the legal system is adjusted will not be only the contents of the legal standards, but also the political, economic and social matters that are governed by these legal standards.