According to the U. S. Copyright office, "A work of authorship is in the “public domain” if it is no longer under copyright protection or if it failed to meet the requirements for copyright protection. Works in the public domain may be used freely without the permission of the former copyright owner."
U.S. Copyright Office: http://www.copyright.gov/help/faq/faq-definitions.html
Works that generally fall into the public domain are:
1. the term of copyright for the work has expired;
2. the author failed to satisfy to meet the copyright standard;
3. U.S. Government works or;
4. facts.
Most of the works in public domain are published in the United States before 1923 since that is the cutoff date used by the law to determine copyright.
If the U.S. government created it, such as pamphlets, or has put it into a law, such as building codes, then it is considered public domain.
| DATE OF WORK | PROTECTED FROM | TERM |
| Created 1-1-78 or after | When work is fixed in tangible medium of expression | Life + 70 years1(or if work of corporate authorship, the shorter of 95 years from publication, or 120 years from creation2 |
| Published before 1923 | In public domain | None |
| Published from 1923 - 63 | When published with notice3 | 28 years + could be renewed for 47 years, now extended by 20 years for a total renewal of 67 years. If not so renewed, now in public domain |
| Published from 1964 - 77 | When published with notice | 28 years for first term; now automatic extension of 67 years for second term |
| Created before 1-1-78 but not published | 1-1-78, the effective date of the 1976 Act which eliminated common law copyright | Life + 70 years or 12-31-2002, whichever is greater |
| Created before 1-1-78 but published between then and 12-31-2002 |
1-1-78, the effective date of the 1976 Act which eliminated common law copyright | Life + 70 years or 12-31-2047 whichever is greater |
1 Term of joint works is measured by life of the longest-lived author.
2 Works for hire, anonymous and pseudonymous works also have this term. 17 U.S.C. § 302(c).
3 Under the 1909 Act, works published without notice went into the public domain upon publication. Works published without notice between 1-1-78 and 3-1-89, effective date of the Berne Convention Implementation Act, retained copyright only if efforts to correct the accidental omission of notice was made within five years, such as by placing notice on unsold copies. 17 U.S.C. § 405. (Notes courtesy of Professor Tom Field, Franklin Pierce Law Center and Lolly Gasaway)
Retrieved from http://www.unc.edu/~unclng/public-d.htm