Despite its crucial role in ensuring quality public services, public procurement faces challenges such as a lack of transparency, unfair resource distribution, and abuse of authority. To address these issues, legal regulations and norms become essential in preventing irregularities and protecting the integrity of public procurement processes. The Public Procurement Act in the Republic of Croatia serves as the fundamental legal framework for regulating public procurement. However, situations often arise that the legislator could not have foreseen, necessitating the precise application of legal provisions to preserve the integrity of the public procurement process. This paper explores legal norms aimed at preventing opacity and preventing abuse in public procurement. It examines the reasons for excluding economic entities from public procurement procedures, the eligibility criteria for these entities, and the methods for proving the selection criteria for economic entities. European regulations and public procurement legislation play a crucial role in shaping the standards and rules that govern procurement procedures in the Republic of Croatia. Through an analysis of legislatively prescribed reasons for excluding economic entities and examples from the practice of competent appeal institutions, this paper draws conclusions about the importance of legal regulation in preserving transparency and integrity in public procurement processes. The paper utilizes extensive literature, laws, and reports from European institutions to provide a comprehensive overview of the current state of public procurement and the challenges it faces. The author of this paper, who has professional experience in public procurement, approaches the topic with a multidisciplinary perspective that includes legal, economic, and ethical viewpoints. The goal of this paper is to contribute to a better understanding of legal regulation in public procurement and its role in maintaining transparency and integrity in this crucial process in the economic life of the Republic of Croatia.