The powers of the Northern Ireland Assembly were set out in the Northern Ireland Act 1998, which formally established the Assembly in law. The Act gave expression to what had been agreed by participants in Northern Ireland’s peace talks, as enshrined in the 1998 Belfast Agreement. Because it was signed on Good Friday (10 April) 1998, the Belfast Agreement is also known as the Good Friday Agreement.

The Belfast/Good Friday Agreement sought to bring to an end decades of violent conflict between Unionists (who want Northern Ireland to remain part of the UK) and Nationalists (who want Northern Ireland to leave the Union and join with the Republic of Ireland to create a new, all-island state, independent of the UK). It led to the creation of a range of new structures and institutions to facilitate a more peaceful way of managing this conflict, including through Unionists and Nationalists sharing power in a new, devolved legislative assembly and executive.

The Northern Ireland Assembly has the power to pass laws in a range of devolved policy areas. These are called ‘transferred matters’ and they include health and social services, education, agriculture, social security, employment and skills, economic development, environmental issues (including planning), and transport. There are two types of areas in which the Northern Ireland Assembly does not have ‘legislative competence’. These are ‘reserved matters’ and ‘excepted matters’. ‘Reserved matters’ are those for which the Assembly does not currently or usually have competence, but for which competence may be transferred under some circumstances or at a future date. These include things like financial services and pensions regulations, international trade and financial markets, and intellectual property. ‘Excepted matters’ are those for which only the UK government in Westminster has legislative competence, and for which competence cannot be transferred to the Northern Ireland Assembly. These include areas like the Crown, currency, international treaties and national security. Any matter not explicitly ‘reserved’ or ‘excepted’ is considered to be ‘transferred’ by default.

In a number of the policy areas for which it has legislative competence, the Northern Ireland Assembly can only pass laws if they have ‘cross community support’. This means that a law will only pass if it has the support of a majority of both Unionists and Nationalists in the Assembly. The passage of the budget for Northern Ireland, for example, requires a cross community vote. Most legislation can be passed by a simple majority, but if a group of 30 or more Members of the Legislative Assembly (MLAs) have particular concerns about a proposed law, then they can present a ‘petition of concern’ to the Speaker of the Assembly, which will make the passage of that law subject to a ‘cross community’ vote.