This publication is presented under www.gov.uk/government/publications/common-travel-area-guidance/common-travel-area-guidance “Today`s agreement provides a platform for closer immigration cooperation, including common measures to protect the CTA from abuse, by preventing potential immigration fraudsters from travelling to Ireland and the Uk. 2.1 Between 1801 and 1922, Ireland was part of the United Kingdom of Great Britain and Ireland. Despite the creation of the Irish state in 1922, the Irish were still regarded as British subjects from the point of view of the United Kingdom. As such, they had the same rights as British citizens in the UNITED Kingdom. Historically, after Ireland`s independence, the Irish continue to have a special status in the United Kingdom, which has resulted in many of the CTA agreements/rights being implicit and stem from that status and not from specific legislation or agreement. The Isle of Man is considered part of the UK for customs purposes, so there are no routine customs checks for travellers arriving from the UK.  There is no border control between the four constituent nations of the United Kingdom, so the land borders between England, Scotland and Wales are fully open. However, Section 8 of the Temporary Commissions Act 1974 provides temporary powers to investigate persons travelling between Northern Ireland and Great Britain.   Appendix 7 of the Terrorism Act 2000 provides for similar powers and remains in force.  Protocol 20 attached to the EU treaties provides that the United Kingdom and Ireland can maintain their specific common travel regimes. In particular, it facilitated the continuation of the opt-out in the Schengen agreements. The main legislation on Schengen visas and common schengen immigration control does not apply.
The withdrawal agreement between the UK and the European Union recognises the common travel space in its protocol for Ireland and Northern Ireland. Article 2 provides for the sustainability of the common travel area. There is no passport control for Irish and British citizens travelling between the two countries. You do not need a passport to enter the other country. Like its previous predecessors, the 2011 agreement is non-binding, with the eighth clause stating that the agreement “is not intended to create legally binding obligations or confer a right, right or benefits on a private or public person or party.”  In 2014, the British and Irish governments introduced an experimental system of mutual recognition of reciprocal visas for the continuation of travel within the CTA.