Ecosystem services progressively became the standard concept of renewed discourses and debates on sustainability. The paper suggests some institutionalist arguments for a critical assessment of the scientific and political processes which led to proclaimed changes within the mainstream framework. We focus on the interactions between theoretical arguments and institutional changes involved by the integration of ecosystem services within policy and law. The political economy of ecosystem services appeared to be dual: on the one hand it could be a seminal framework to implement new strategies to overcome the failures of our development models; but, on the other hand, the strength of epistemological principles inherited from mainstream economics could enforce the processes of commodification through radical changes concerning the Humans and Nature relationships. The demonstration originally integrates law and economics to encompass the different aspects of the institutional changes.