Expanded Copyright (self-paced course)

When a work that could be copyrighted is not copyrighted, it is in the Public Domain. This means that it can be used without asking or paying for permission, including making and distributing copies and derivative works. It cannot be licensed, because no one owns the rights to license it; however copies can be sold by anyone. 

Considerations of academic integrity (citing, not plagiarizing) still apply, of course!

U.S. Federal Government Publications

Works published by the U.S. Federal Government are in the public domain from the time they are created. For example, you can search USA.gov for public domain images and videos that include NASA, the US Geographical Survey, etc. Reports and data put out by agencies like the Center for Disease Control and Prevention, the Department of Education, the Department of Labor, the Department of Agriculture, the Food and Drug Administration, the Environmental Protection Agency, the State Department, the Department of Defense, the Department of Health and Human Services, the National Parks Service, the Department of Justice, and more are also public domain. (Sensitive materials are unavailable, but everything that is meant for a wide audience is public domain.) 

Grants To the Public Domain

This is in a legal gray area. Up until the late 1980s, it was customary in the U.S. for an author to be able to grant a work to the Public Domain directly merely by stating it. But! Public Domain isn't a legally protected status, and pitting an obsolete U.S. custom against a ratified international treaty (the Berne Convention) which doesn't specifically allow it is very shaky ground. 

Of course most works' copyright is only defended by their rightsholders, and if those rightsholders do not care to enforce a copyright that they didn't want anyway, you are probably safe using a pre-1978 work that was "granted to the public domain" for educational purposes. The same goes for contemporary Creative Commons works that are marked CC0 or "No Rights Reserved." That still doesn't absolutely guarantee your safety, because "copyright trolls" make a business of suing for copyright infringement of other people's works. So be careful using these kinds of works in high-profile or money-making applications.

Aging Out of Copyright and Falling Into the Public Domain

All works that are under copyright will eventually fall into the Public Domain. The rules that govern that are very complicated and will be explored in greater detail. Here are the simple and straightfoward parts:

• If it is a U.S. work that was formally published before 1923 1926, as of 2023, it is already in the public domain.
• Works published in the U.S. in 1923 1926, as of 2023, are now in the public domain too, because enough time has elapsed!
• If it is a foreign work that was formally published before 1890, it is already in the public domain.
• If you can't determine the date or whether it was formally published, but it was definitely before 1890, it's already in the public domain.
• Regardless of where it was published, if it is a work that has been created since 1978, and it was authored by one or more individual persons, it will fall into the Public Domain 70 years after the death of the longest-lived author, calculated from December 31 of the year of death. So if the last author to die died on May 16, 2018, the work would fall into the Public Domain on January 1, 2089. This is called the Life + 70 Rule. 
• Regardless of where it was published, if it is a work that has been created since 1978, and it was authored by an organization, it will fall into the Public Domain either 95 years after publication or 120 years after creation (whichever is shorter.) Again, it is calculated from December 31 of that year, and falls into the Public Domain on the following January 1. 

SO! That is the simple part. Yes, it gets way more complicated than that when you are dealing with works published in that long middle period in the 20th century. That is why you have a librarian!