Note:  Another very informative site on this topic is Mary Minow, Expiration of Works into the Public Domain (June 28, 2002). 

    For any work published prior to 1978 (with proper copyright (©) notice), copyright lasted for an initial term of 28 years, renewable in the 28th year at first for an additional 28 years, then (with the 1976 Copyright Act but actually beginning in 1961 or 1962) for an additional 47 years, and finally (with the Sonny Bono Copyright Term Extension Act of 1998) for an additional 67 years.  If a work published prior to 1964 was not formally renewed, it entered the public domain when the initial 28-year term expired.  (For works published after 1963, renewal became automatic in 1992.)  If the copyright was renewed, the term was thus 75 years from the year of publication (expiring on Dec. 31 of the 75th year following the initial publication) until the Sonny Bono act extended this to 95 years.  (Note, however, that if a work with a foreign author went into the U.S. public domain because of a failure to follow formalities of prior U.S. copyright law (typically publication without copyright notice or failure to renew), copyright was RESTORED by section 514 of the Uruguay Round Agreements Act of 1994, codified at 17 U.S.C. section 104A.  This constitutionality of this restoration of expired copyrights is being is being judically challenged in the Golan case.  See Challenge to Constitutionality.)

    Thus, if a work was published in 1922 or earlier, it is now in the public domain.  Works that were published between 1923 and 1963 have a 95-year term, provided the copyright was formally renewed in the 28th year.  Works published between 1964 and 1977 have a flat 95-year term.  Works by individual authors created (not merely published) after 1977 have a term of the author's life + 70 years.  Works by corporate authors ("works made for hire") created after 1977 have a term of 95 years.  (The combination of the automatic renewal legislation in 1992 and the Sony Bono term extension legislation in 1998 has the effect that virtually nothing will enter the public domain for a full 20 years, at which time we can expect the same folks, or their successors, to be back in Congress begging for yet another extension!)

    So, how does one determine when a work was first published?  If a copy is available with a copyright notice, the notice should contain the year of first publication.  Of course, new editions (derivative works) often contain notices with the year of first publication of the derivative work and not the original, but if the date is prior to 1923, you can be confident that that particular work, and all predecessors, are in the public domain.  In other cases, a more tedious process is necessary.

    Every year the Copyright Office publishes a Catalog of Copyright Entries.  This is in hard copy form for the years up to 1982 and solely in electronic form since then.  The Catalog is on-line for entries since 1978, but that does not help much for the older works that are the primary focus of copyright term extension and our opposition to it.  If you are near a library that has the Catalog (or can visit the Copyright Office) you can try looking through it to find the work in which you are interested.  (For literary works, see below.)  The thing to remember is that even if a work was first published between 1923 and 1963, and so was potentially saved by the Sonny Bono Copyright Term Extension Act, it is nevertheless in the public domain unless a timely renewal application was filed with the copyright office.  (Works first published between 1964 and 1977 must be assumed to be under copyright for the full 95-year period.)  Consequently, it is probably best to check the renewal entries in the Catalog for the years that are 27-28 years after the suspected year of first publication.  If the year of first publication is not known, you simply must check the renewal entries for all years that are conceivably in the 27-28 year range after first publication.

     The On-Line Books Page is a website that facilitates access to books that are freely readable over the Internet.  A list of what they have found to be available is found here.

     I have made a short list of Subverted PD Works that I will be enlarging with time as new items come to my attention.  I call it "subverted" because the works there listed should be either now or in the next few years in the public domain, but their passing to that status was subverted by this special-interest giveaway known as the Sonny Bono Copyright Term Extension Act.

     An invaluable contribution to the resolution of some of these problems may be found at the US Catalog of Copyright Entries (Renewals), maintained at a web site in England.  This site contains transcriptions of the renewals of US copyright for literary works, ie books (omitting laws, law reports & digests, instruction manuals, parts lists, instruction papers, maps, forms & patterns), contributions to periodicals & periodicals themselves (omitting law reports & digests), and dramatic (& other performance) works.  While this does not help much in searching the public domain status of films or music, it makes things much easier for works of literature.  Knowing whether a work was renewed (if it was originally published before 1964) can be critical to determining its copyright status.  We should all feel most grateful that someone has taken it upon him- or herself to get this material on line.  This site has complete scans of the Catalog for renewal entries made in 1950 (renewals of works first published in 1922-23), 1951 (1923-24), 1952 (1924-25), 1953 (1925-26), 1954 (1926-27), and 1955 (1927-28), with partial listings for 1956, 1957, 1959, 1960, 1961, 1962, 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, and 1977.  These are actual images in TIFF format of the pages of the Catalog.  They are especially useful in searching by the name of the author of the original work, because the entries are in alphabetical order by author names.  Renewals effected after 1977 (and before 1992, when renewal ceased to be required) are available online.  This is a searchable website, which makes the whole process much easier.