Government
Type: Constitutional monarchy with parliamentary democracy.
Constitution: September 16, 1975.
Branches: Executive--British monarch (chief of state), represented by governor general; prime minister (head of government). Legislative--unicameral parliament. Judicial--independent; highest is Supreme Court.
Administrative subdivisions: 19 provinces and the national capital district (Port Moresby).
Major political parties: National Alliance (NA), People's Progress Party (PPP), Pangu Parti, People's Democratic Movement (PDM), and Melanesian Alliance (MA).
Suffrage: Universal over 18 years of age.

Government of Papua New Guinea
Papua New Guinea, a constitutional monarchy, recognizes the Queen of England as head of state. She is represented by a Governor General who is elected by Parliament and who performs mainly ceremonial functions. Papua New Guinea has three levels of government--national, provincial, and local. There is a 109-member unicameral Parliament, whose members are elected every 5 years. The Parliament in turn elects the prime minister, who appoints his cabinet from members of his party or coalition.

Members of Parliament are elected from 19 provinces and the national capital district of Port Moresby. Parliament introduced reforms in June 1995 to change the provincial government system, with regional (at-large) members of Parliament becoming provincial governors, while retaining their national seats in Parliament.

Papua New Guinea's judiciary is independent of the government. It protects constitutional rights and interprets the laws. There are several levels, culminating in the Supreme Court.

Papua New Guinea's politics are highly competitive. Members of Parliament are elected on a "first past the post" system, with winners frequently gaining less than 15% of the vote. There are several parties, but party allegiances are not strong. Winning candidates are usually courted in efforts to forge the majority needed to form a government, and allegiances are fluid. No single party has yet won enough seats to form a government in its own right.

Papua New Guinea has a history of changes in government coalitions and leadership from within Parliament during the 5-year intervals between national elections. New governments are protected by law from votes of no confidence for the first 18 months of their incumbency, and no votes of no confidence may be moved in the 12 months preceding a national election. In an effort to create greater stability by reducing incessant votes of no confidence, the Integrity of Political Parties Act was passed in 1999, forbidding members of each party in Parliament from shifting loyalty to another party.

The last national election was held in June 2002. The election was characterized by a 75 percent turnover in sitting members of Parliament. A number of veteran politicians lost their seats and a number of independents were elected. The government was formed by a coalition of several parties. Sir Michael Somare, the leader of the Melanesian Alliance (and the nation’s first Prime Minister in 1975), was elected Prime Minister.

On Bougainville Island, a rebellion had been underway from early 1989 until a truce came into effect in October 1997 and a permanent cease-fire was signed in April 1998. A peace agreement between the Government and ex-combatants was signed in August 2001. Under the eyes of a regional peace-monitoring force and a UN observer mission, the government and provincial leaders have established an interim administration and are working toward complete surrender of weapons, the election of a provincial government and an eventual referendum on independence.
source: http://www.state.gov