The Instrument of Government (Swedish: 1809 års regeringsform) adopted on 6 June 1809 by the Riksdag of the Estates was one of the fundamental laws that made up the constitution of Sweden from 1809 to 1974. It came about after the Coup of 1809, when the disastrous outcome in the Finnish War led Swedish nobles and parts of the army to revolt, forcing King Gustav IV Adolf to abdicate, and to go into exile.
For half a century, starting with the Instrument of Government (1719), often referred to as the Age of Liberty, Sweden had enjoyed parliamentary rule under the Riksdag of the Estates, but in 1772 that was ended by a coup d'état perpetrated by Gustav III: the Revolution of 1772. The coup enabled Gustav III to rule as an enlightened despot. Gustav III's son, Gustav IV Adolf, succeeded him but proved a less charismatic ruler, and the change of sides of Russia in the Napoleonic wars prompted the disastrous Finnish War and the loss of Finland, settled in the Treaty of Fredrikshamn. This provided momentum for the Swedish nobility and other forces to depose the king and restore political power to the Estates.
The aged and childless brother of Gustav III, Charles XIII was made king in 1809, but he was a mere puppet in the hands of the Estates and the question of his successor had to be solved. The election, by the Riksdag of the Estates, of the French Marshal and Prince of Ponte Corvo Jean-Baptiste Bernadotte in 1810, provided not only a successor, but also a vital regent and a new dynasty. The rights of Bernadotte's successors to accede to the Swedish throne were codified in an amendment to the constitution in the form of the Act of Succession (1810).
The Instrument of Government of 1809 replaced the Instrument of Government of 1772. It established a separation of powers between the executive branch (the King) and the legislative branch (the Riksdag of the Estates). The King and Riksdag possessed joint power over legislation (article 87, constitutional law in articles 81-86), while the Riksdag had sole power over the budget and state incomes and expenses (articles 57-77) including military burdens (article 73). While the King's power was somewhat reduced compared to the enlightened absolutism of Gustav III, the new document enabled the King to take a more active role in politics than during the Age of Liberty.
Originally, ministers were politically responsible solely to the king, who appointed and dismissed them. However, they were legally responsible to the Riksdag and a special court (Riksrätten) according to a special statute and to law in general if they committed legal offences (articles 106 and 101-102).
As the Riksdag's authority grew, it became increasingly difficult for a government to stay in office solely with the Crown's support. This culminated in 1907, when a government was chosen that was dependent more on the confidence of the Riksdag than on that of the King. However, in 1914, when Gustaf V made a speech opposing the program of the incumbent liberal government, it resigned, and the King appointed a conservative government of civil servants responsible to him. After a great liberal victory in 1917, it was obvious that the King could no longer pick a government entirely of his choosing, nor could he keep it in office against the will of the Riksdag. At that time, it was definitively established that ministers were politically responsible (not just legally) to the Riksdag, notwithstanding the Instrument stating that "the King alone shall govern the realm" (article 4). From then on, while ministers were still formally appointed by the King, convention required him to ensure they had the support of a majority in the Riksdag and to act on his ministers' advice. In 1975, it was replaced by a new Instrument of Government, which stripped the king of even nominal political power and made Sweden a de facto crowned republic.
During the period when it was in force several important reforms took place without affecting its status. In 1866 the Four Estates were replaced by a bicameral parliament, and in 1876 the office of the Prime Minister of Sweden was introduced. In the early 20th century universal suffrage was introduced and the country became a de facto parliamentary monarchy. In 1970 the parliament was transformed from a bicameral legislature to a unicameral one.