The principle of mutual trust, whose fundamental importance is recognized by the CJEU, is not mentioned in the Treaties, but nonetheless, it plays an essential role for the EU integration process and has become a structural principle of the EU law. In addition to its role as a basis for a large set of EU rules in the areas such as the internal market and the area of freedom, security and justice, this principle is also closely related to the EU founding values including the rule of law. Having in mind that is not a “blind trust” but an assumption, it is applied through ensuring compliance with the Union law for which both the Member States and the European Commission share responsibility, inter alia, by means of the infringement procedure. Under Article 259 TFEU, Member States are also entitled to bring a direct action against another Member State for an alleged infringement of an obligation under the Treaties. However, it is extremely rare for a Member State to take action upon the Article 259 TFEU and its potential remains untapped till now. This contribution aims to answer why do Member States are inactive in terms of invoking the infringement procedure. It argues that infringement procedure initiated by a Member State against another Member State should not be perceived as a violation of the mutual trust between them but as a tool to uphold the mutual trust and to protect the Union’s founding values, including the rule of law.

The doctrine of supremacy is essential to the uniformity of the EU legal edifice. It had no formal basis in the Treaty Law but was developed by the Court of Justice of the EU by means of its conception of the "new legal order" (Costa v ENEL). Therefore, the corollary of sovereignty of the EU legal order is the supremacy of EU law: any norm of EU law takes precedence over any provision of national law. From the CJEU's perspective, supremacy entails duty for the national courts to 'set aside' any conflicting national norm when an EU rule applies in a given case. Ultimately, the acceptance and application of the supremacy of EU law are dependent on the Member States. Despite its invention, acceptance of the doctrine of supremacy has been the main challenge within the overall integration process. Recent ruling from the German Constitutional Court (the Bundesverfassungsgericht) on the legality of the European Central Bank's Programme marked that the supremacy issue cannot be put 'ad acta' and still continues to be surrounded with ambiguity and controversy against its unconditional acceptance as the CJEU requires. This paper summarizes the most remarkable aspects of the foundations of the supremacy doctrine and the conceptual basis on which the Member States accord supremacy to EU law, as well as its scope and limits. All this is necessary in order to be able to determine the perspectives for ensuring the supremacy of EU law, while highlighting its importance for the future of the European integration.

This paper examines the role of the Environmental Impact Assessment (EIA) as a tool of the EU environmental legislation and an aid to the decision-making process aiming at prioritization of environmental interests over other interests. The EIA Directive has evolved after more than 35 years of implementation while at the same time, EU acquis has grown and new policies have developed along with the broadening of the European integration process. Hence, this contribution provides an overview of the application and effectiveness of the EIA process and of the main challenges that served as indications for further modifications in order to enhance the EIA as an effective instrument of environmental protection. Special emphasis is put on the judicial control imposed by the Court of Justice of the EU in the light of the environmental justice notion and articulation of environmental rights under the EIA Directive(s). The paper concludes with reflections on the environmental considerations raised by the EIA process, arguing that although the full potential of the EIA Directive has yet to be realized, having a separate directive that focuses on the likely environmental effects in the decision-making process ultimately makes a difference.

Since the rule of law was introduced into the EU enlargement policy, its role within the conditionality policy has advanced gradually so that it has become the cornerstone of the accession process. This paper analyses the evolution of the rule of law promotion in the process of EU enlargement with a focus on the Western Balkans and strives to identify what the main challenges are in this regard and the main reasons why the EU has made the rule of law central to its new enlargement methodology. Drawing on the experience of the Europeanisation process of the CEE countries, the paper examines the different approaches in terms of the promotion of the rule of law within the Copenhagen political accession criteria. It finds that with regard to the accession process of the Western Balkans, the EU is no longer satisfied with 'reforms on paper' and strives to apply more active leverage. However, the internal challenges for the rule of law within the EU and the often 'neglected' fourth Copenhagen criterion − absorption capacity of the Union itself referring to its capability to include new members − also affect the process. Rule of law conditionality has been compromised not only by more focus on the box-ticking benchmark fulfilment exercise than on substance, but also by the lack of credibility on the side of the EU that has undermined the pre-accession conditionality. The most illustrative case in this regard is the accession process of North Macedonia that is analysed as a case study in order to identify the main challenges and shortcomings of the EU enlargement policy. The paper proposes that the rule of law promotion and the overall Europeanisation process must rest on a credible merit-based accession process that involves clear commitments on both sides − candidate countries but also the EU.