There are three distinct legal jurisdictions in the United Kingdom

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The United Kingdom has four legal systems, each of which derives from a particular geographical area for a variety of historical reasons: English law, Scots law, Northern Ireland law and since 2007, purely Welsh law (as a result of the passage of the Government of Wales Act 2006 by Parliament). Overarching these systems is the law of the United Kingdom, also known as United Kingdom law (often abbreviated UK law). UK law arises from laws applying to the United Kingdom and/or its citizens as a whole, most obviously constitutional law, but also other areas, for instance tax law.In fulfilment of its former EU treaty obligations, European Union directives were actively transposed into the UK legal systems under the UK parliament's law-making power. Upon Brexit, EU law was transplanted into domestic law as "retained EU law", though the UK remained temporarily in alignment with EU regulations during the transition period from 31 January to 31 December 2020.
There are three distinct legal jurisdictions in the United Kingdom: England and Wales, Northern Ireland and Scotland. Each has its own legal system, distinct history and origins.
There is a substantial overlap between these three legal systems and the three legal jurisdictions of the United Kingdom: England and Wales, Scotland, and Northern Ireland. Unlike the other three, Welsh law is not a separate legal system per se, merely the primary and secondary legislation generated by the Senedd, interpreted in accordance with the doctrines of English law and not impacting upon English common law (except where such Welsh legislation ousts a common law rule by virtue of being a superior form of law).
The UK does not have a single legal system because it was created by the political union of previously independent countries. Article 19 of the Treaty of Union, put into effect by the Acts of Union in 1707, created the Kingdom of Great Britain but guaranteed the continued existence of Scotland's and England's separate legal systems.The Acts of Union of 1800, which joined Great Britain and Ireland into the United Kingdom of Great Britain and Ireland, contained no equivalent provisions but preserved the principle of different courts to be held in Ireland, of which the part called Northern Ireland continues to follow as part of the United Kingdom.
Each legal system defaults to its jurisdiction, each of whose courts further that law through jurisprudence. Choice of which jurisdiction's law to use is possible in private law: for example a company in Edinburgh, Scotland and a company in Belfast, Northern Ireland are free to contract in English law. This is not so in public law (for example, criminal law), where there are set rules of procedure in each jurisdiction.
English law refers to the legal system administered by the courts in England and Wales, which rule on both civil and criminal matters. English law is based on the principles of common law. English law can be described as having its own legal doctrine, distinct from civil law legal systems since 1189.
There has been no major codification of the law, rather the law is developed by judges in court, applying statute, precedent and case-by-case reasoning to give explanatory judgments of the relevant legal principles. These judgments are binding in future similar cases (stare decisis), and for this reason are often reported in law reports.
The courts of England and Wales are headed by the Senior Courts of England and Wales, consisting of the Court of Appeal, the High Court of Justice (for civil cases) and the Crown Court (for criminal cases). The Supreme Court is the highest court in the land for both criminal and civil appeal cases in England and Wales (also in Northern Ireland cases and civil cases in Scots law) and any decision it makes is binding on every other court in the same jurisdiction, and often has persuasive effect in its other jurisdictions. On appeal, a court may overrule the decisions of its inferior courts, such as county courts (civil) and magistrates' courts (criminal). The High Court may also quash on judicial review both administrative decisions of the Government and delegated legislation. Before the Supreme Court of the United Kingdom was created in October 2009, the highest appellate body was the Appellate Committee of the House of Lords (usually just referred to as "The House of Lords").
After the Acts of Union, in 1707 English law became one of two legal systems in different parts of the same united kingdom and has been influenced by Scots law, most notably in the development and integration of the law merchant by Lord Mansfieldand in time the development of the law of negligence. Scottish influence may have influenced the abolition of the forms of action in the nineteenth century and extensive procedural reforms in the twentieth. Since the accession of the United Kingdom to the European Communities in 1973 English law has also been affected by European lawunder the Treaty of Rome.
Welsh law is the primary and secondary legislation generated by the Senedd, using the devolved authority granted in the Government of Wales Act 2006 (amended substantially by Wales Act 2014 and Wales Act 2017) and in effect since May 2007. Each piece of Welsh legislation is known as an Act of Senedd Cymru.
However, as there is no criminal law within contemporary Welsh law, Wales is not generally considered a fourth jurisdiction of the United Kingdom. This is because the judiciary and the courts follow England and Wales law, which is made by the Parliament at Westminster, and is not specific to Wales. Although Welsh law is recognised as separate in operation, this is not sufficient for Wales to constitute a separate legal jurisdiction.
A commission set up in 2017 by the First Minister of Wales known as "The Commission on Justice in Wales" and chaired by Lord Thomas of Cwmgiedd, looked into the operation of justice in the country. It aim was to further clarify the legal and political identity of Wales within the UK constitution. The commissions report was released in October 2019 and recommended the full devolution of the justice system. This would formalise Wales as the fourth jurisdiction of the UK.
The law of Northern Ireland is a common law system. It is administered by the courts of Northern Ireland, with ultimate appeal to the Supreme Court of the United Kingdom in both civil and criminal matters. The law of Northern Ireland is closely similar to English law, the rules of common law having been imported into the Kingdom of Ireland under English rule. However, there are important differences.
The sources of the law of Northern Ireland are Irish common law, and statute law. Of the latter, statutes of the Parliaments of Ireland, of the United Kingdomand of Northern Ireland are in force, and latterly statutes of the devolved Northern Ireland Assembly. The courts of Northern Ireland are headed by the Court of Judicature of Northern Ireland, consisting of the Northern Ireland Court of Appeal, the Northern Ireland High Court of Justice and the Northern Ireland Crown Court. Below that are county courts and magistrates' courts. The Supreme Court is the highest court in the land for both criminal and civil appeal cases in Northern Ireland and any decision it makes is binding on every other court in the same jurisdiction and often has persuasive effect in its other jurisdictions.
Scots law is a unique legal system with an ancient basis in Roman law. Grounded in uncodified civil lawdating back to the Corpus Juris Civilis, it also features elements of common law with medievalsources. Thus Scotland has a pluralistic, or 'mixed', legal system, comparable to that of South Africa, and, to a lesser degree, the partly codified pluralistic systems of Louisiana and Quebec. Since the formation of the Kingdom of Great Britain under the 1707 Acts of Union, Scots law has shared a legislature with England and Wales, and while each retained fundamentally different legal systems, the 1707 Union brought English and Welsh influence upon Scots law, and vice versa.
Since the accession of the United Kingdom to the European Communitiesin 1973 Scots law has also been affected by European law under the Treaty of Rome. The establishment of Scottish Parliament in 1999, which legislates within domestic areas of legislative competence, has created a further major source of Scots law.
The chief courts are the Court of Session, for civil cases,[7] and the High Court of Justiciary, for criminal cases.[8] The Supreme Court of the United Kingdom serves as the highest court of appeal for civil cases under Scots law, with leave to appeal from the Court of Session not required as a general rule.[9] However unlike in the rest of the United Kingdom the Supreme Court has no role as a highest court of appeal for criminal cases. Sheriff courtsdeal with most civil and criminal cases including conducting criminal trials with a jury, known as sheriff solemn court, or with a sheriff and no jury, known as sheriff summary court. The sheriff courts provide a local court service with 49 sheriff courts organised across six sheriffdoms.[10] The Scots legal system is unique in having three possible verdictsfor a criminal trial: "guilty", "not guilty" and "not proven". Both "not guilty" and "not proven" result in an acquittal with no possibility of retrial.[11]
The Cabinet Secretary for Justice is the member of the Scottish Government responsible for Police Scotland, the courts and criminal justice, and the Scottish Prison Service, which manages the prisons in Scotland.

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