This legal hare was set running by a London political scientist, Brendan O'Leary, in The Irish Times on February 5th. The proper legal view, I submit, using United Kingdom, international and Irish constitutional law, is that London acted perfectly legally. It is, in contrast, the Irish Government which may be at risk of breaching the Belfast Agreement. First, United Kingdom law. Northern Ireland, in municipal law, has been an integral part of the United Kingdom for almost 200 years.
Parliamentary sovereignty remains an important domestic legal doctrine.
The first constitutional act implemented much of the Belfast Agreement, signed by the two governments on April 10th, 1998. There is no way, under the Belfast Agreement, it subsequently became jointly responsible for devolution in Northern Ireland, with or without suspension. The Irish Government's code of omerta over the Boland case in Dublin in 1974 contributed to the end of the Sunningdale power-sharing experiment. Second, international law. The UK never undertook to put Northern Ireland under permanent joint authority.