In a relatively short period of time, the fourth edition of the book became necessary due to the legislative changes that occurred in Law 4412/2016 with the provisions of Law 4782/2021 "Modernization, Simplification and Reform of the Regulatory Framework of Public Contracts, Special Provisions for Supplies in the Defense and Security Sectors, and other provisions for Development, Infrastructure, and Health" (Government Gazette A' 36/9-3-2021).

These significant changes concern both the substantive law of public contracts and the law of legal protection in the field of related disputes, both at the administrative level (preliminary appeals before the Hellenic Single Authority for Public Contracts, already the Hellenic Administrative Court of Appeals) and at the judicial level. However, modifications are also made in the field of dispute resolution arising from the execution of the contract at the stage of legal protection through administrative appeals.

In addition, Law 4912/2022 (Government Gazette A' 59) created a unified independent authority for all public contracts resulting from the merger of the Hellenic Single Independent Authority for Public Contracts (HSIAPC) and the Authority for the Examination of Preliminary Appeals (AEPA). The result is the creation of a new dynamic in the field of public contracts, which has led, among other things, to terminological harmonization of this book.
As with previous editions of the book, the present edition is accompanied by an update of the existing relevant bibliography and case law of the courts (Supreme Administrative Court, Council of State, Court of Cassation, Court of Audit, political courts, and regular administrative courts).

Once again, I would like to express my warm thanks to both the readership for their reception of my book and the trust they show in me, as well as to the publishing house "Sakkoulas Publications (Athens-Thessaloniki)" for their support and willingness to undertake this fourth edition of my book. Also, to the lawyer and PhD candidate in Law, Ms. Frantziska-Aikaterini Raikou, MDE in Public Law of the Law School of Athens, Master in Law and Economics of the University of Piraeus, for her contribution to the update of this edition.