The Parliament of Bermuda is the bicameral legislative body of the British Overseas Territory of Bermuda. Based on the Westminster system, one of the two chambers (lower house) is elected, the other (upper house), appointed. The two chambers are: House of Assembly (36 members; elected for a five-year term in single seat constituencies) Senate (11 appointed members) Originally, the House of Assembly was the only house in the legislature. It held its first session in 1620, making Bermuda's Parliament amongst the world's oldest legislatures and the oldest extant legislature in the Americas. An appointed Privy Council originally performed roles similar to those of an upper house and of a cabinet. A major constitutional change took place in 1968. The Legislative Council was replaced with an appointed Senate. Political parties were legalised, and universal adult suffrage adopted. The position of Premier was also introduced as leader of the ruling party, and an official opposition.