Treasonable Offences Act 1925

The crime of treason is defined by Article 39 of the Constitution of Ireland, adopted in 1937, which states:

treason shall consist only in levying war against the State, or assisting any State or person or inciting or conspiring with any person to levy war against the State, or attempting by force of arms or other violent means to overthrow the organs of government established by the Constitution, or taking part or being concerned in or inciting or conspiring with any person to make or to take part or be concerned in any such attempt.

Before the 1921 treaty that led to the creation of the Irish Free State (Saorstát Éireann), treason was governed under the laws of the United Kingdom of Great Britain and Ireland. Many historical Irish nationalist insurgents executed for high treason against the Crown of the United Kingdom or of the earlier Kingdom of Ireland are considered heroes in independent Ireland.

Section 1(1) of the Treasonable Offences Act 1925 (enacted under the 1922 Constitution) defined treason as:

The maximum punishment was death. The Act also defined the offences of misprision of treason and of encouraging, harbouring, or comforting any person engaged in levying Saorstát Éireann or engaged, taking part, or concerned in any attempt to overthrow by force of arms or other violent means the Government of Saorstát Éireann as established by or under the Constitution of 1922. The Treasonable Offences Act 1925 was the first comprehensive and permanent measure designed to deal with offences against the state. Section 3 reenacted portions of the Treason Felony Act 1848, while sections 4 and 5 dealt, respectively, with the usurpation of executive authority and assemblies pretending to parliamentary functions. Section 6 prohibited the formation of pretended military or police forces and section 7 proscribed unauthorised drilling.

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