This thesis, examines three research questions concerning the coherence between the European Union (EU) rules about State aid for environmental protection and the “polluter-pays-principle” (PPP) in the context of the free allocation practice in the European Union Emissions Trading System (EU ETS).  The aim of the first research question is to study whether the free allocation of emission rights within the EU ETS is compatible with the EU State aid rules. The conclusion to this research question is that the free allocation practice does fulfil the criteria to constitute State aid but that the Commission has permitted derogations against this prohibition, provided certain conditions such as necessity and proportionality are fulfilled.   The second research question is whether the free allocation method is compatible with the PPP. The PPP can be divided into an economic dimension and a legal dimension and it is concluded that the free allocation practice is contrary to at least the legal dimension of the PPP. According to the OECD, exceptions from the principle can be made but the EU has not established conditions for when such derogations from the PPP can be made.   The third research question concerns the compatibility between the EU State aid rules and the PPP. Generally there is no disharmony between the State aid rules and the PPP, since the PPP should not be seen as a mere prohibition against aid to polluters, but can also be considered a complement to State aid rules. However in the specific case of the free allocation rules in the EU ETS, State aid measures contrary to the PPP are carried out. Since the EU has not established conditions for whether derogations from the PPP can be made, it is concluded that the free allocation practice within the EU ETS does expose a disharmony between the PPP and the State aid rules. It is suggested that the EU clarifies the conditions for permitting derogations from the PPP, in preparation for the fourth phase of the EU ETS.

L’objectif de cette étude est d’appréhender, à travers l’exemple du système européen d’échange des quotas d’émission de gaz à effet de serre, les conditions d’efficacité d’un instrument particulier de réalisation du développement durable : la technique de marché. Définie comme un instrument de police consistant en la poursuite d’un objectif de politique publique, préalablement défini par les pouvoirs publics, au moyen de la création volontaire d’un marché, c’est-à-dire l’organisation d’échanges d’« unités » entre opérateurs économiques, la technique de marché est utilisée de manière privilégiée en matière environnementale. La création ex nihilo d’un marché pour protéger l’environnement ne doit pas induire en erreur : la technique de marché ne conduit pas à une substitution de la liberté à la puissance publique. Au contraire, la technique de marché n’est efficace que si elle est sous-tendue par une action publique forte. Une intervention permanente – au stade de l’élaboration et de la mise en oeuvre de cet instrument – et multiforme – au niveau international, régional et national – de la puissance publique est nécessaire. La « main invisible » du marché ne produit ses effets que grâce à la « main visible » de la puissance publique. / By taking the example of the European Union emission trading system, the objective of the present study is to understand the conditions of effectiveness of a specific tool: the market-based instrument. Market-based instrument is defined as a tool of policing aiming at the achievement of a public policy objective (pre-established by public authorities) with the creation of a market, i.e. the organisation of exchanges of “units” between economic operators. This tool is widely used in environmental law. The ex nihilo creation of a market in order to protect the environment must not mislead: the market-based instrument does not lead to a shift from public action to freedom. To the contrary, the effectiveness of the market-based instrument depends on a strong public action. A permanent (i.e. both during the preparation and the implementation of this tool) and multifaceted (i.e. at international, regional and national levels) public intervention is therefore required. The “invisible hand” of the market could only be effective with the “visible hand” of public authorities.