The Arbuthnott Commission on Boundary Differences and Voting Systems was set up in July 2004 by Alistair Darling, then Secretary of State for Scotland, under the chairmanship of Sir John Arbuthnott, to examine various consequences of having four different electoral systems in Scotland, and different boundaries for constituencies of the House of Commons (Parliament of the United Kingdom, at Westminster) and the Scottish Parliament (Holyrood).
In 2004, Scotland had three different electoral systems: plurality (first past the post) for Westminster and local government elections, and two different systems of proportional representation (PR) for European Parliament and Scottish Parliament elections.
The commission published its final report in January 2006, making various recommendations.
Full implementation of the commission's recommendations would be beyond the competence of the Scottish Parliament, and would require Westminster legislation.
All the main political parties in Scotland participated in a consultation process.