(cabinet). It sits at Parliament Buildings at Stormont in Belfast. The Assembly has authority to legislate in a field of competences known as "transferred matters". These matters are not explicitly enumerated in the Northern Ireland Act 1998 but instead include any competence not explicitly retained by the Parliament at Westminster. Powers reserved by Westminster are divided into "excepted matters", which it retains indefinitely, and "reserved matters", which may be transferred to the competence of the Northern Ireland Assembly at a future date. Health, criminal law and education are "transferred" while royal relations are all "excepted". While the Assembly was in suspension, due to issues involving the main parties and the Provisional Irish Republican Army (IRA), its legislative powers were exercised by the UK government, which effectively had power to legislate by decree. Laws that would normally be within the competence of the Assembly were passed by the UK government in the form of Orders-in-Council rather than legislative acts. There has been a significant decrease in violence over the last twenty years, though the situation remains tense, with the more hard-line parties such as Sinn Féin and the Democratic Unionist Party now holding the most parliamentary seats (see Demographics and politics of Northern Ireland). Judiciary The United Kingdom does not have a single legal system due to it being created by the political union of previously independent countries with the terms of the Treaty of Union guaranteeing the continued existence of Scotland's separate legal system. Today the UK has three distinct systems of law: English law, Northern Ireland law and Scots law. Recent constitutional changes saw a new Supreme Court of the United Kingdom come into being in October 2009 that took on the appeal functions of the Appellate Committee of the House of Lords. The Judicial Committee of the Privy Council, comprising the same members as the Supreme Court, is the highest court of appeal for several independent Commonwealth countries, the UK overseas territories, and the British crown dependencies. England, Wales and Northern Ireland Both English law, which applies in England and Wales, and Northern Ireland law are based on common-law principles. The essence of common-law is that law is made by judges sitting in courts, applying their common sense and knowledge of legal precedent (stare decisis) to the facts before them. The Courts of England and Wales are headed by the Senior Courts of England and Wales, consisting of