Under the law of the United Kingdom, high treason is the crime of disloyalty to the Crown. Offences constituting high treason include plotting the murder of the sovereign; committing adultery with the sovereign's consort, with the sovereign's eldest unmarried daughter, or with the wife of the heir to the throne; levying war against the sovereign and adhering to the sovereign's enemies, giving them aid or comfort; and attempting to undermine the lawfully established line of succession. Several other crimes have historically been categorised as high treason, including counterfeiting money and being a Catholic priest.
The Treachery Act 1940 was an Act of the Parliament of the United Kingdom effective during World War II to facilitate the prosecution and execution of enemy spies, suspended afterwards, and repealed in 1968 or 1973, territory depending. The law was passed on 23 May 1940, in the month after Nazi Germany invaded France and Winston Churchill became prime minister.
Arson in royal dockyards and armories was a criminal offence in the United Kingdom and the British Empire. It was among the last offences that were punishable by capital punishment in the United Kingdom. The crime was created by the Dockyards etc. Protection Act 1772 passed by the Parliament of Great Britain, which was designed to prevent arson and sabotage against vessels, dockyards, and arsenals of the Royal Navy.
Misprision of treason is an offence found in many common law jurisdictions around the world, having been inherited from English law. It is committed by someone who knows a treason is being or is about to be committed but does not report it to a proper authority.
The Treason Act 1351 is an Act of the Parliament of England wherethrough, according to William Blackstone, common law treason offences were enumerated and no new offences were, by statute, created. It is one of the earliest English statutes still in force, although it has been very significantly amended. It was extended to Ireland in 1495 and to Scotland in 1708. The Act was passed at Westminster in the Hilary term of 1351, in the 25th year of the reign of Edward III and was entitled "A Declaration which Offences shall be adjudged Treason". It was passed to clarify precisely what was treason, as the definition under common law had been expanded rapidly by the courts until its scope was controversially wide. The Act was last used to prosecute William Joyce in 1945 for collaborating with Germany in World War II.
The Treason Felony Act 1848 is an Act of the Parliament of the United Kingdom of Great Britain and Ireland. Parts of the Act are still in force. It is a law which protects the King and the Crown.
The Criminal Lunatics Act 1800 was an Act of the Parliament of Great Britain that required and established a set procedure for the indefinite detention of mentally ill offenders. It was passed through the House of Commons in direct reaction to the trial of James Hadfield, who attempted to assassinate King George III.
The Treason Act 1695 is an Act of the Parliament of England which laid down rules of evidence and procedure in high treason trials. It was passed by the English Parliament but was extended to cover Scotland in 1708 and Ireland in 1821. Some of it is still in force today.
The Treason Act 1842 is an Act of the Parliament of the United Kingdom of Great Britain and Ireland. It was passed early in the reign of Queen Victoria. The most recent person to be convicted under the Act was Jaswant Singh Chail, on 3 February 2023, and he was sentenced to nine years in prison on 5 October 2023. He was the first person in more than 40 years to be convicted under the act.
The Sedition Act 1661 was an Act of the Parliament of England, although it was extended to Scotland in 1708. Passed shortly after the Restoration of Charles II, it is no longer in force, but some of its provisions continue to survive today in the Treason Act 1695 and the Treason Felony Act 1848. One clause which was included in the Treason Act 1695 was later adapted for the United States Constitution.
The Treason Act 1800 was an Act of the Parliament of the Kingdom of Great Britain. It assimilated the procedure on trials for treason and misprision of treason to the procedure on trials for murder in certain cases. It was passed as a result of an attempt on the life of George III by James Hadfield earlier that year. The Criminal Lunatics Act 1800 was passed at the same time.
The Criminal Law Act 1967 is an Act of the Parliament of the United Kingdom that made some major changes to English criminal law, as part of wider liberal reforms by the Labour government elected in 1966. Most of it is still in force.
The Treason Act 1708 is an Act of the Parliament of Great Britain which harmonised the law of high treason between the former kingdoms of England and Scotland following their union as Great Britain in 1707.
The Treason (Ireland) Act 1821 is an Act of the Parliament of the United Kingdom. It extended most of the English Treason Act 1695 to Ireland. Previously the 1695 Act only applied to England and Scotland.
The Treason Act 1547 was an Act of the Parliament of England. It is mainly notable for being the first instance of the rule that two witnesses are needed to prove a charge of treason, a rule which still exists today in the United States Constitution.
The Treason Outlawries (Scotland) Act 1748 was an Act of the Parliament of Great Britain which applied only to Scotland. Its long title was "An Act to ascertain and establish the Method of Proceeding to and upon Outlawries for High Treason and Misprision of High Treason, in Scotland."
The Succession to the Crown Act 2013 is an Act of the Parliament of the United Kingdom that altered the laws of succession to the British throne in accordance with the 2011 Perth Agreement. The Act replaced male-preference primogeniture with absolute primogeniture for those in the line of succession born after 28 October 2011, which means the eldest child, regardless of gender, precedes any siblings. The Act also repealed the Royal Marriages Act 1772, ended disqualification of a person who married a Roman Catholic from succession, and removed the requirement for those outside the first six persons in line to the throne to seek the Sovereign's approval to marry. It came into force on 26 March 2015, at the same time as the other Commonwealth realms implemented the Perth Agreement in their own laws.
The Treason (Ireland) Act 1854 is an Act of the Parliament of the United Kingdom of Great Britain and Ireland. It extended part of the Treason Act 1708 to Ireland, specifically the rules about giving the defendant advance notice of the witnesses and jurors in his case. It was repealed as regards Northern Ireland by the Treason Act 1945, which abolished the unique procedural rules which applied in treason cases. As of 16 January 2020 it remains in force in the Republic of Ireland.
The Administration of Justice Act 1939 was an Act of the Parliament of the United Kingdom that modified the law in England and Wales with regards to juries in England and Wales.
The European Union (Withdrawal) Act 2018 is an Act of the Parliament of the United Kingdom to repeal the European Communities Act 1972, and for parliamentary approval to be required for any withdrawal agreement negotiated between the Government of the United Kingdom and the European Union. Initially proposed as the Great Repeal Bill, its passage through both Houses of Parliament was completed on 20 June 2018 and it became law by Royal Assent on 26 June.
