A work of the United States government, is defined by the United Statescopyright law, as "a work prepared by an officer or employee of the United States Government as part of that person's official duties." Under section 105 of US copyright law, such works are not entitled to domestic copyright protection under U.S. law and are therefore in the public domain.
This act only applies to U.S. domestic copyright as that is the extent of U.S. federal law. The U.S. government asserts that it can still hold the copyright to those works in other countries.
Publication of an otherwise protected work by the U.S. government does not put that work in the public domain. For example, government publications may include works copyrighted by a contractor or grantee; copyrighted material assigned to the U.S. Government; or copyrighted information from other sources.
Further, the copyright status of works by subnational governments of the United States is governed by its own set of laws.
^17 U.S.C.§ 101 "A 'work of the United States Government' is a work prepared by an officer or employee of the United States Government as part of that person's official duties."
^House Report No. 94-1476, p.59 ("The prohibition on copyright protection for United States Government works is not intended to have any effect on protection of these works abroad. Works of the governments of most other countries are copyrighted. There are no valid policy reasons for denying such protection to United States Government works in foreign countries, or for precluding the Government from making licenses for the use of its works abroad.").