In the European Union, the United Kingdom, Commonwealth, Hong Kong and the United States, a green paper is a tentative government report and consultation document of policy proposals for debate and discussion. A green paper represents the best that the government can propose on the given issue, but, remaining uncommitted, it is able without loss of face to leave its final decision open until it has been able to consider the public reaction to it.  Green papers may result in the production of a white paper. They may be considered as grey literature.
A green paper in Canada, like a white paper, is an official government document. Green papers tend to be statements not of policy already determined, but of propositions put before the whole nation for discussion. They are produced early in the policy-making process, while ministerial proposals are still being formulated. Many white papers in Canada have been, in effect, green papers, while at least one green paper - that on immigration and population in 1975 - was released for public debate after the government had already drafted legislation.
Similarly, in the UK, green papers are official consultation documents produced by the government for discussion both inside and outside Parliament, for instance when a government department is considering introducing a new law.
A green paper released by the European Commission is a discussion document intended to stimulate debate and launch a process of consultation, at European level, on a particular topic. A green paper usually presents a range of ideas and is meant to invite interested individuals or organizations to contribute views and information. It may be followed by a white paper, an official set of proposals that is used as a vehicle for their development into law.
Discussion of defence policy in Australia, 2000
A major review of defence policy in Australia culminated in a white paper issued in December 2000. Prior to this a discussion paper was released in June 2000. This discussion paper was in nature what is known as a green paper (and was sometimes referred to as such).
Copyright in the knowledge economy, 2008
The purpose of the EU green paper is to foster a debate on how knowledge for research, science and education can best be disseminated in the online environment. The green paper aims to set out a number of issues connected with the role of copyright in the "knowledge economy" and intends to launch a consultation on these issues (compare to this document). The EU asks for answers and comments until 30 November 2008.