Q. Are government documents copyrighted?
Works of the U.S. federal government are generally not protected by copyright in the United States and are automatically in the public domain (17USC§ 105); however, there are numerous exceptions and refinements to this rule.
For a detailed explanation of how copyright law is applied to government publications, see Frequently Asked Questions About Copyright: 3.0 U.S.Government Works and 4.0 Works Created Under a Federal Contractor Grant on the CENDI Web site.
Also, be sure you know the difference between copyright infringement and plagiarism.
State and local governments may, and often do, claim copyright in their publications. It is their prerogative to set policies that may allow, require, restrict, or prohibit claim of copyright on some or all works produced by their government units. (See CENDI FAQ 3.1.3)