The Underlying Law Act 2000 adopted the sources of the underlying law as customary law and the common law of England in force immediately before independence. The Act provides for methods and processes for developing the underlying law.
For commentary on the Act and its implications, see:
Jean Zorn and Jennifer Corin Care; Everything Old is New Again: The Underlying Law Act of Papua New Guinea,, LawAsia Journal  61-97 (UniM access)
The Queen of England is the head of state for Papua New Guinea, as represented by the governor-general.
The Prime Minister holds executive power. The website contains information about the activities of the Prime Minister.
Accessing Papua New Guinean legislation in any form is difficult as it appears that the government and legislators do not intend on publishing legislation, even in hard copy. According to the Foreign Law Guide, ongoing political and constitutional disputes within the legislature have meant that the development of new legislation or the modernisation of existing laws has lapsed.
As a result, there is no uniform or extensive coverage of legislation available.
Pacific Islands Legal Information Institute (PACLII) collects and publishes legal materials from 20 Pacific Islands countries. The materials consist mainly of primary materials such as court decisions and legislation but also include decisions of various tribunals and panels or secondary information such as court rules or bench books. There is additionally a Pacific Islands Treaty Database.
Papua New Guinea information includes
Sessional legislation (for the years 1951, 1974, 1977, 1978, 2010 - not comprehensive)
Laws of the Territory of Papua (1888 - 1945)
Laws of the Territory of New Guinea (1921 - 1945)
Note: the currency and completeness of these databases is not guaranteed
The Food and Agricultural Organisation of the United Nations maintains a database of national laws and regulations relating to food, agriculture and renewable natural resources. This database (FAOLEX) contains some Papua New Guinean legislation.
pngInLaw is a subscription database which includes Papua New Guinea legislation, judgments, indexes, citators and treaties and PNG law generally. The database is updated 2 or 3 times a year.
Papua New Guinea Income Tax Legislation is a subscription database from CCH Australia which includes Papua New Guinea income tax legislation, double tax agreements and tax cases as well as Papua New Guinea GST and Stamp Duties Legislation. The information is also available as a looseleaf service.
The Centre for Democratic Institutions at Australian National University supports democractic processes and institutions in South East Asia and the Pacific through knowledge sharing and interchange. A range of documents relating to Papua New Guinea are available.
The National Research Institute is Papua New Guinea's leading think tank on public policy and development-related issues and trends. The Institute advocates the need for research-based information to form the basis for policy debates and discussions.