The United States Constitution gives Congress the power to create copyright law in order to promote the dissemination of knowledge. “The Congress shall have the power . . . to promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors exclusive Right to their respective Writings and Discoveries” (Article 1, Section 8). Copyright law seeks a balance between the exclusive rights of the creators and the use of created works to improve society.
Copyright law, as defined in Title 17 of the United States Code, protects "original works of authorship fixed in a tangible medium of expression" for a limited period. Copyright applies both to traditional media (books, records, etc.) and to digital media (electronic journals, web sites, etc.). Copyright protects the following categories of works:
Works whose protection has expired and those which were never eligible for protection are in the public domain.
The copyright holder has the exclusive rights to:
Ownership of a copyrighted work includes the right to control the use of that work. Use of such work by others during the term of the copyright requires either permission from the author or reliance on one of the limits provided in Sections 107-110 of U.S. Copyright Law. Failure to do one or the other will expose the user to a claim of copyright infringement for which the law provides remedies including payment of money damages to the copyright owner.(Section 506).
The current term of protection is 70 years after the death of the author. This applies to most works created after 1977 whether published or not.
The fact that a work is no longer available for purchase (out of print) does not, by itself, indicate that it is no longer protected by copyright.
Works published prior to 1923 are in the public domain, no longer protected by copyright.
For works created and/or published between 1923 and 1978, there are varying requirements for notice (the © symbol) and terms of protection.
Legislation passed by the U.S. Congress since 1976 has extended the term of copyright protection for some categories of works. As a result, it is often difficult to determine exactly when a specific work enters the public domain.
For more precise information on the duration of copyright protection based on year of publication, see Digital Copyright Slider (American Library Association).
Other useful tools for determining the length of copyright:
In order to promote progress in knowledge and arts, the copyright law limits the exclusive rights of copyright holders.
Section 107, on fair use, is the legal basis for much of the copying done to support instruction in educational institutions.
Section 108 addresses reproduction by libraries and archives.
Section 109 describes the effect of a lawful sale of a copy of a protected work.
Section 110 details when copyrighted works may be performed and displayed for educational purposes.
Copyright holders may sign publisher agreements that restrict their original rights.