What is Inter Se Agreements Cum Tertiis

Regional integration between European Union Member States is a process that will usually result in differentiated integration (i.e., some EU states moving further in integration efforts than others). EU law provides a mechanism for such deeper integration called “enhanced cooperation.” Even though this mechanism has been applied in some cases now, this chapter will show that even where certain EU competences apply, enhanced cooperation is by no means a replacement for so-called inter se or satellite agreements or treaties between EU States but outside of union law and EU integrative structures. Rather, if inclusion of a third country is desired or necessary, enhanced cooperation cannot apply, and there is no other option than to conclude an inter se agreement cum tertiis.