The following information is courtesy of the National Archives Office of General Counsel staff:
Just because a photograph is on the internet or unattributed doesn't mean it's not copyrighted or someone doesn't own the intellectual property.
We can't offer guidance about all of the photos on the internet in all countries, nor can we confirm the copyright status of any particular item. We can provide some basic information about the copyright status of items in the National Archives of the United States, and the general advice that you should consult a lawyer who specializes in copyright issues with any specific questions.
The National Archives and Records Administration's (NARA) holdings come from a wide variety of sources, but for copyright purposes, they can generally be divided into two categories: works of the U.S. government and deeded items. Works of the U.S. government, created by federal employees, in the course of performing their official duties are not eligible for copyright protection. Information in NARA's Catalog about the creator of the record should help a user determine, for themselves, whether records were created by U.S. government employees. A word of caution however: some agencies contract with private entities to create films, photographs, software, etc. In those cases, whether the contractor was allowed to claim copyright on the work is a question about the terms of the contract. For moving images, this information may or may not be present in the production file accompanying the record.
Other items in NARA's holdings have been donated to us with a deed. Those items may contain copyright interests which were held by the original creator of the works. Sometimes, copyright transferred to NARA in the deed. In these situations, NARA treats the items as public domain material and makes them freely available. In other situations, the copyright holder maintained their rights and did not transfer them to NARA. In those cases, any user will need permission from the copyright holder to reuse the works or copy them. In our Catalog you may see these items designated as having a "use restriction" on them.
It is also possible that a deed was silent about the copyright interest, throwing these questions into a legal gray area. This is also indicated by a possible "use restriction" in the Catalog.
A few other items of note: the notion of a "public domain" particularly for government works is an American concept. Many countries copyright the works of their central governments. Likewise, many state governments copyright their works. Finally, even U.S. government works may implicate the publicity rights of famous people. For example, you cannot take a photograph from NARA's holdings, taken by a White House photographer, of President Clinton drinking his favorite soda, and use it to sell Coca-Cola. This would infringe on President Clinton's publicity rights under state law. Publicity rights continue after death.
For more information, please see the attached use statements on Special Media records and Archival Materials in Presidential Libraries.
You may also want to consult this earlier question which concerned the copyright status of German photographs: Copyright of confiscated German WW2 railway photographs .
We hope this information is helpful. Thanks for posting your question on History Hub!
NARA Use Statement.pdf 96.7 KB