This article seeks to analyse what is the purpose competition law serves in today’s society and reflect on how significant public authorities are in its application, both with an active and passive role. It analyses the main channels open to competition authorities, in order to bring to light possible breaches of competition principles committed by administrations and which are the most useful tools for stopping them. The paper considers that the role of public administrations in markets as regulators, providers of aid, economic operators or facilitators of contracting between companies is highly significant and may have a major influence on those markets. The proper exercise of these functions results in highly positive values for consumers and in an increase of the common good. Improper actions of the administration can be seriously harmful to the general interest. It concludes that ensuring the proper operation of the markets is essential if periods of economic recession are to be overcome. As such, public administrations must fulfil their mandate of guaranteeing the general good, shying away from sectoral interests that could bring increased short-term benefits but result in dysfunctions and harm for the common good and for consumers.