Under the present copyright act, the typical duration of a copyright is the life of the author, plus 70 years (works for hire and anonymous works endure for 120 years from creation or 95 years from publication, whichever is shorter). Section 302(a), (c). Unfortunately, it gets a little more complicated for works fixed before 1978 when the current copyright act went into effect. The rules vary for works based on whether they were published or not before 1978.
Under section 303, published works that were fixed before 1923 (95 years is the maximum copyright duration for works published before 1978) are now in the public domain. Works published after 1923 and before 1978 enjoy a maximum of 95 years of copyright protection under the act. However, that copyright protection is tied up with the renewal process, which was required every certain period of years under the 1909 act. If a published work required a renewal to be filed with the copyright office before 1964, and the author failed to appropriately renew, that published work would become a part of the public domain and lost its copyright protection. However, the authors of the 1976 act did look back to works that required a renewal after 1964, and made the renewal automatic for all those works. As of today, the maximum period of copyright protection is 95 years for works that were published before 1978.
As to unpublished works, these works were not protected by federal copyright until 1978. Therefore, states provided varying degrees of protection. The 1976 act authors wanted to preempt state copyright protection, by providing protection for all works that were fixed, regardless of whether the work was published or not. For unpublished works that were made recently to 1976, giving these works protection for the life of the author plus fifty years (now seventy years) would be reasonable. But what about works that were unpublished but originally fixed in the 1800s? Some state laws provided for perpetual copyright protection, which the federal law could not provide because of the constitutional mandate.
Congress decided that section 303(a) would provide a savings clause for works unpublished before 1978: if published between 1978 and 2002, the works would enjoy protection until at least 2047. If the works were unpublished in 1978 and remained so in 2002, copyright protection would continue until at least 2002.
Now, renewals are today automatic under the Act. However, the renewal intervals serve a second purpose, which is found in section 304 – the ability of the heirs of a deceased author to terminate transfers of rights of the author’s copyright by providing notice to the party or parties to whom the copyright was assigned. The timing to terminate such a grant is keyed to the renewal cycle of the copyright. See Section 304(c)(2).