Wolff identifies this issue as being implicitly addressed in the Sunningdale Agreement. Constitutional relevance Because the Good Friday Agreement binds the British government on several points of law in Northern Ireland, it has de facto become part of the constitution of the United Kingdom. Legal commentator David Allen Green described it as "a core constitutional text of the UK, and of Ireland ... of more everyday importance than hallowed instruments such as, say, Magna Carta of 1215 or the 1689 Bill of Rights". Because the Agreement commits the government to enshrine the European Convention on Human Rights in law and allows Northern Ireland residents access to the European Court of Human Rights, it required enactment of the Human Rights Act 1998. Consequently, the Agreement was a significant factor preventing the repeal of that Act and its replacement with the proposed British Bill of Rights that Prime Minister David Cameron had promised. The Agreement also makes reference to the UK and the Republic of Ireland as "partners in the European Union", and it was argued in R (Miller) v Secretary of State for Exiting the European Union that the Agreement meant that the consent of Northern Ireland's voters was required to leave the European Union (Brexit). The UK Supreme Court unanimously held that this was not the case, but the Agreement has nevertheless strongly shaped the form of Brexit. Brexit During the negotiations on Britain's planned 2019 withdrawal from the European Union, the EU produced a position paper on its concerns regarding the Good Friday Agreement. The paper identified a range of issues including the avoidance of a hard border, North–South cooperation, citizenship, and the Common Travel Area. Anyone born in Northern Ireland, who is also entitled to Irish citizenship, will also be able to retain EU citizenship after Brexit. Under the European Union negotiating directives for Brexit, the UK was asked to satisfy the other EU members that these topics had been addressed in order to progress to the second stage of Brexit negotiations. In order to protect North–South co-operation and avoid controls on the Irish border, the UK, led by Prime Minister Theresa May, agreed to protect the Agreement in all its parts and "in the absence of agreed solutions, the United Kingdom would maintain full alignment with those rules of the Internal Market and the Customs Union which, now or in the future, support North-South cooperation, the all-island