The term liberalisation refers to Article 3 of the Treaty on the Functioning of the European Union (TFEU), which states that the "Union shall have exclusive competence in […] the establishing of the competition rules necessary for the functioning of the internal market".
Article 106(3) of the Treaty entrusts the Commission with a specific surveillance duty "in the case of public undertakings and undertakings to which Member States grant special or exclusive rights".
The Commission is given the power to, and must "where necessary, address appropriate directives or decisions to Member States" which enact or "maintain in force any measure contrary to the rules contained in the Treaty, in particular to those rules provided for in Article 18 and Articles 101 to 109".
However, the Commission is under no obligation to take decisions under Article 106(3) since this provision mentions that it should take such decisions only "where necessary". This leaves full discretion to the Commission to assess the need to adopt a decision.
In this regard, Article 106(2) of the Treaty introduces an exception to the application of the rules of the Treaty when the latter would obstruct the provision of "services of general economic interest". However, even where this exception applies, special rights must not go beyond what is necessary for the performance of the service.
Relevant Articles from the Treaty on the Functioning of the European Union
Relevant articles from the Treaty on European Union
Services of General Economic Interest (SGEI)