How to defend environment as it scapes the territorial logic of a sovereign State, such as the high seas or migration birds? The current means to defend this res communis, which we will define as "global concerns": common wellbeing and concerns will depend on the capability to act, and on the instances provided by the present International Law. In the light of its inadequacy, the actio popularis or other institutions such as the WEO show signs of eventual solutions. Keywords Res nullius/res communis-"common heritage" of mankind-"common concerns"-Actio popularis.