At the end of April 2017, May told Juncker over dinner in Downing Street that UK migration law would apply after Brexit to EU nationals already residing in the UK, which implied a considerable decrease in rights compared to EU law. Social benefits, access to healthcare and family reunion rights were more generous under EU free movement than UK migration law, which in turn is stricter than EU law on deportations. Once negotiations started, the UK team led by the Home Office altered that position radically and accepted EU law as the starting point of the work. The decision to replicate EU law concepts in the Withdrawal Agreement avoided a discussion from scratch on each right, which would have taken time and most probably become acrimonious.

On the money, in contrast, the UK argued for the first three months of the talks that Brexit cancelled all its debts. The chapter on citizens’ rights advanced much faster therefore in the first weeks than the chapter on money, which worried Barnier. It would be hard to defend that the EU was holding out on citizens’ rights because of unresolved budget claims. Activists on citizens’ rights criticized the package approach and advocated a stand-alone agreement. They underestimated how much the EU needed the upper hand that came with sequencing, given where the UK was politically on taking back border control, reducing free movement of EU nationals and rejecting the role of EU judges after Brexit. Whereas the EU imposed sequencing of talks primarily to make sure the UK paid all its financial obligations, sequencing became equally important for a good deal on citizens’ rights since it gave Barnier's team levers to push through more effective enforcement mechanisms and overcome the UK's resistance to joint enforcement as an intrusion of its sovereignty.

Earlier in 2016, Nick Timothy, May's chief of staff, tried to convince national governments to sort out citizens’ rights before notification with a vague proposal that hinted at the protection of a few rights only and unclear enforcement tools. It opened the door to discretionary behaviour by the Home Office