The term public domain refers to the point in time when intellectual property is no longer protected by national or international copyright law. Once the property in question enters the public domain, others may reuse the work for free. There are three primary reasons that result in intellectual property entering the public domain: 1 – The creator of the work failed to complete the requirements of copyright in his or her country within specified guidelines in relation to the publishing date of the work, 2- The work was completed by the creator as a product of the U.S. and some other national governments, 3 – The copyright term of the intellectual property has expired.

When Does a Copyright Expire?
Copyright expiration is more complex than the typical patent expiration period of 20 years. In the United States, if a creative work was produced from January 1, 1978 or newer, the general rule is that it is covered by copyright for 70 years after the creator of the work has died. If the work was made by two or more people, the copyright term extends for 70 years after the death of the last surviving creator.

The rules for copyright expiration change slightly for works that are produced for hire, are pseudonymous, or anonymous works. In these cases, the copyright timeframe extends for a total length of time of 95 years after the original publication for a total of 120 years after the year it was created with expiration on occurring on whichever date comes first. In the case of anonymous or pseudonymous works, if the creator’s identity becomes known and application is made to extend the copyright to that author, the rules applying to named creators becomes the governing code. For this to occur, the creator or other person with an interest in the work must file an official statement with the copyright office stating the required background of the work, publication, copyright, and information on the creator(s).How Do Works Enter Public Domain

If a party or person has an interest in applying the copyright death expiration to a creative work, a submission must be made to the Copyright Office stating the facts of the death, the work copyrighted, source of verification of the creator’s death, and the information of the person or organization making the application. On a similar note, statements of a work’s creator still living may also be completed in the same manner in the event this status comes into question. Barring a statement to contradict, the presumption of a work’s creator’s life is presumed to be 95 years from the first year of publication or 120 years from the creation of the intellectual property whichever occurs first. The previously mentioned rules, however, supersede this rule of copyright expiration if they are found to apply.

In the United States, once a copyrighted work has entered the public domain, it has been generally accepted that it cannot become copyrighted again. In the European Union, however, precedent was set to restore copyrights on some material previously in the public domain in order to synchronize policies across the EU. Although this is generally thought of as a single instance, it is a precedent for the act of removing material from the public domain.

Intellectual Property Not Covered by Copyright Law
There is a fine-line in copyright law that precludes any underlying ideas that are foundation ideas not explicitly tied to the production or creation of a work from being copyrighted. For example, if a mathematical formula is the underlying theory behind a software program used in a commercial product, the formula is normally considered to be in the public domain where the computer algorithm, code, and software that result from the formula will likely be copyrighted work. Also, if a work was made before copyright or patent law existed, the work can not have copyright extended to it, but ancillary work such as language translations for texts like the bible, or modern applications of ancient theories or solutions may have copyright law applied to them.

Work Produced by Federal Governments
Generally, creative works produced by most federal governments or their employees acting in the line of duty are considered to be part of the public domain within that country. Similarly, when previously copyrighted material becomes a statute or law it enters the public domain within that country.

Sound Recordings and the Public Domain
The copyright and public domain laws are somewhat different for sound or music recordings. If a recording was not published officially but created before February 15th, 1972 it falls under the state of recording’s common law protection. The recording will enter the public domain on February 15th, 2067. If the recording was made after February 15th, 1972, the copyright remains valid for the life of the creator plus 70 years. For any work produced by an anonymous or pseudonymous creator it is 120 years. The earliest that unpublished recordings will enter the public domain is February 15th, 2067.

For sound or music recorded in the United States and published prior to February 15th, 1972 the same rules apply to the copyright of the material as for unpublished works. If a work was created between February 15th 1972 and 1978 and was published without notice of the owner, the work is considered to be in the public domain. If published from February 15th 1972 and 1978 the copyright extends for 95 years from publication. If the work was published from 1978 onwards, the copyright extends for 70 years after the death of the author, or if produced through a corporate entity, the shorter period of 95 years from publication or 120 years from the creation date.

Books and the Public Domain
If a book was created prior to January 1st, 1923, it is now considered to be in the public domain. Once the initial Copyright law was created in 1923, all literary books published until 1963 were copyrighted for 28 years with an option to extend the copyright for another 47 years. This law was later extended from 47 to 67 years from the publication date. The copyright rules changed again in 1964 automatically extending the copyright of books for another 67 years. In 1978 the copyright law changed making books protected for the life of the author plus 70 years after the author’s death or until December 31st 2002 depending on which date occurs first. For any books written between January 1st, 1978 and December 31st, 2002, the copyright of the work extends for 70 years beyond the author’s death or until the end of the 2047 calendar year.