The head of the government is the Prime Minister (PM) who is the leader of the cabinet who currently hold the most seats in the house in either a majority or minority government. The PM and Cabinet hold offices in both the executive and legislative branches. Both the PM and Cabinet are significantly involved in all parliament affairs. This is known as the fusion of powers. The fusion of powers is a combination between the legislative and executive powers of the PM and the Cabinet, and they both hold office in the executive and legislature. A key feature of a parliamentary system is that the government may hold office as long as it holds majority support in the legislature. The leader of a party can serve as PM indefinitely, as long as they continue to hold a stable majority or minority government. If defeated on a vote of confidence the PM must resign or call for an election. The PM holds the power of dissolution where he may dissolve the party or order a new election before their term is up. In parliamentary systems there is a large amount of power vested in the PM and Cabinet, provided they hold a majority government in the house. The Constitution in Canada is based on the British North America Act (BNA), 1867 which was renamed in 1982 to the Constitution Act of 1867. The BNA act cannot be compared to the American Constitution because it was established as a framework for admitting colonies and territories into a federation. The rules for allocating power to the federal parliament and to the provincial legislatures were defined in the BNA Act. The original document was not developed to create an independent country. Independence from the United Kingdom was not the basis for developing the original system of government for Canada. This first constitution gives Canada both a constitutional monarchy and a parliamentary democracy and defines how the executive government will be composed with the Senate and the House of Commons.