The Instrument of Government, or Regeringsformen, adopted on June 6, 1809 by the Riksdag of the Estates was the constitution of Sweden from 1809 to 1974. It came about following the disastrous outcome in the Finnish War, when King Gustav IV Adolf was forced to abdicate and was succeeded by his uncle, Charles XIII.
The Instrument of Government is the first sovereign codified--and written--constitution in the world. It was drafted by Major-General John Lambert in 1653, and granted executive power to the Lord Protector. Although this post was elective, not hereditary, it was to be held for life.