ABSTRACT
During the unprecedented Brexit negotiations towards securing a UK–EU withdrawal agreement, there has been a significant gap-filling operation carried out by the European institutions in order to cope with an extremely complex process on the basis of the very scant regulation offered by Article 50 TEU. In some cases, the legal voids have been filled simply by extending EU rules on international treaty-making to the withdrawal process despite the clause only referring to paragraph 3 of Article 218. In other cases, separate Treaty principles have applied, notably, the principle of sincere cooperation due to the status of Member and not of third country of the withdrawing state. Finally, other specific withdrawal rules have emerged anew from the practice. All of this has allowed the process to be designed by the EU in its interests while at the same time favouring the emergence of a heavily conditioned legal procedure of EU withdrawal that is different both from withdrawal mechanisms in ordinary international organisations and in comparison to other EU external action.
