This book deals with the peculiarities of the Bidding Law and its nuances in relation to practical activities in the quest to guarantee the common good and the public interest. Specifically, it seeks to demonstrate that the legislation relating to public procurement is capable of providing this service, provided that it is implemented in accordance with the provisions contained in the constitutional principles and the national legal system, culminating in the achievement of the noble principle of Public Efficiency. The aim was to clarify aspects of the legislation that have repercussions on the results obtained by the state and consequently on the quality of the services offered to society as a whole. It reports possible flaws or behaviours that substantially interfere with its degree of public effectiveness. From an overall viewpoint, it analyses the main vices that distort public practices and set the precedent for mismanagement and misappropriation of public resources. It provides subsidies for practices that aim, within the law, to provide better results and the achievement of the State’s primary objectives, which are reflected in the solidification of the Public Administration as a guarantor of social order and progress.