The office of Lyon King of Arms dates from the 14th century. The position may incorporate the much older Celtic office of royal Seanchaidh or of King's Poet with responsibility for keeping the royal genealogy and attending the inauguration (later coronation) of the King.
The Lord Lyon is the sole King of Arms in Scotland. He is Head of the Heraldic Executive and the Judge of the Court of the Lord Lyon which has jurisdiction over all heraldic business in Scotland.
On ceremonial occasions the Lord Lyon is accompanied by Her Majesty's Officers of Arms, all of whom are members of the Royal Household. They are at present Rothesay Herald and Snawdoun Herald, and Unicorn Pursuivant, Ormond Pursuivant and Dingwall Pursuivant.
The Officers of Arms may be consulted on matters of heraldry and genealogy by members of the public and may represent their clients before the Lyon Court.
An Act of the Scottish Parliament of 1592 gave the Lord Lyon responsibility for prosecuting as a criminal offence anyone who uses unauthorised Arms. The Court has its own Procurator Fiscal, an independent official prosecutor.
In 1672 a further Act of the Scottish Parliament authorised the creation of the Public Register of All Arms and Bearings in Scotland. This Register is maintained by the Lyon Clerk and Keeper of the Records and contains an official copy of every Coat of Arms granted in Scotland since 1672.