The UK government announced that all British and Irish citizens born in Northern Ireland would be treated as EU citizens for immigration purposes, making the official rule change in Parliament on Thursday.

This rule change follows the case of an Irish woman, Emma DeSouza, who applied for a residence card for her US-born husband in 2015. Although DeSouza had never held a British passport, the UK Home Office rejected her application because it deemed her to be a British citizen.

DeSouza challenged the decision on the grounds that the terms of the Good Friday Agreement allowed her to identify as either British, Irish or both. The first tier tribunal ruled in favor of DeSouza, but the Home Office appealed and won.

Irish foreign affairs minister Simon Coveney pushed for a rule change, which the UK government did on Thursday. The change will last from August 24 until June 2021.