High treason in the United Kingdom

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 , 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.

High treason was formerly distinguished from petty treason, a treason committed against a subject of the sovereign, the scope of which was limited by statute to the murder of a legal superior. Petty treason comprised the murder of a master by his servant, of a husband by his wife, or of a bishop. Petty treason ceased to be a distinct offence from murder in 1828, and consequently high treason is today often referred to simply as treason.

Considered to be the most serious of offences, high treason was often met with extraordinary punishment, because it threatened the security of the state. Hanging, drawing and quartering was often employed. The last treason trial was that of William Joyce, "Lord Haw-Haw", who was executed by hanging in 1946.

Since the Crime and Disorder Act 1998 became law, the maximum sentence for treason in the UK has been life imprisonment.

High treason today consists of:

See the English History section below for detail about the offences created by the 1351 Act.

In addition to the crime of treason, the Treason Felony Act 1848 (still in force today) created a new offence known as treason felony, with a maximum sentence of life imprisonment instead of death (but today, due to the abolition of the death penalty, the maximum penalty both for high treason and treason felony would be the same—life imprisonment). Under the traditional categorisation of offences into treason, felonies, and misdemeanours, treason felony was merely another form of felony. Several categories of treason which had been introduced by the Sedition Act 1661 were reduced to felonies. While the common law offences of misprision and compounding were abolished in respect of felonies (including treason felony) by the Criminal Law Act 1967, which abolished the distinction between misdemeanour and felony, misprision of treason and compounding treason are still offences under the common law.

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