Public domain and CC0

A museum uploads a 1908 photograph of a temple. The file carries a Public Domain Mark. A publisher copies it, crops it, and sells prints. A second publisher finds the same image with a CC0 dedication and does the same. Both believe they are free of copyright conditions. One is wrong. Public domain and CC0 are the two Creative Commons tools that appear to release a work from copyright, but they operate on different legal foundations and carry different risks. Here is the direct answer, the exact license condition, the decisive exception, and the safest next step for each tool. Below it, ten guides answer the specific questions that arise when you are ready to apply or reuse a CC0 work, mark something as public domain, or handle material whose copyright may have expired.

• CC0: A public-domain dedication with a waiver, a fallback license where waiver is not effective, and a non-assertion promise limited to remaining Copyright and Related Rights. It aims to remove copyright and related-right conditions as far as the affirmer is legally able.
• Public Domain Mark (PDM): Marks material believed free of known copyright restrictions worldwide. It changes no rights. The marker is not the copyright holder and is not waiving anything.
• What They Are Not: Neither is one of the six 4.0 International licenses. CC0 is a legal tool; PDM is a label. PDM does not grant permission. CC0 attempts to waive all permission requirements.
• Remaining Rights: Neither tool guarantees that privacy, publicity, trademark, patent, contract, cultural-heritage or other law permits a use. Those rights survive and must be checked separately.

CC0 is the tool to use when you control the rights and want to dedicate a work to the public domain as completely as the law allows. The person applying CC0, the affirmer, must be the copyright holder or have express authority. Creative Commons does not register the work, verify ownership, or become a party to the dedication.

Three elements make up the tool: a waiver of copyright and related rights to the maximum extent permitted by law; a fallback license that applies if the waiver is ineffective in a particular jurisdiction; and a non-assertion promise limited to remaining Copyright and Related Rights. Under CC0 1.0, the waiver and fallback license are intended to work together. The fallback license grants the same permissions the waiver intended.

Credit is not a legal condition of CC0. Citation and research integrity can still make attribution proper. The affirmer should exclude material they do not control, such as samples or third-party content, from the dedication.

When to Apply CC0

Apply CC0 only if you are the sole copyright holder or have clear authority from every rights holder. Confirm joint authors, employment ownership, commissioned-work terms, performer rights, and any third-party inclusions first. No registration is required. The official chooser helps create a notice but does not validate ownership. Use CC0 1.0 Universal for a new dedication.

Do not use CC0 for software code. Use a recognised free open-source software license instead. Documentation and non-code assets may carry a separate CC0 dedication if they are marked clearly.

What CC0 Does Not Cover

CC0 cannot remove rights that are not within the affirmer's control. Moral rights, privacy rights, publicity rights, trademark rights, patent rights, and contract rights may all remain. The dedication does not license patent or trademark rights. CC0 1.0 addresses moral, privacy and personality rights only to the limited extent stated in its legal code.

Possession of a CC0-marked copy is not a guarantee that the uploader owned all necessary rights or that every component is covered. A museum that uploads a photograph of a public-domain painting, for example, may hold a separate copyright in the photograph itself; CC0 applies only to that photographic copyright, not to the underlying painting.

The Public Domain Mark changes no rights. It is a label applied by someone who believes the work is free of known copyright restrictions worldwide. The marker is not the copyright holder and is not waiving anything. PDM is appropriate only for material believed to be in the public domain everywhere, not for material whose status is uncertain or varies by country.

Copyright status depends on jurisdiction, author, publication facts, term, restoration rules and the type of work. Do not compute a specific work's status from a single publication year. A US public-domain result does not apply worldwide. A work published in 1923 may be public domain in the United States but still under copyright in Europe. PDM does not grant permission; it states a belief that permission is unnecessary. If you rely on PDM and the work turns out to be protected, you have no license and may be liable for infringement.

When to Use the Public Domain Mark

Use PDM on material you have researched thoroughly and are confident is free of known copyright restrictions in every country where it will be reused. That research must account for the rule of the shorter term, restoration of copyright for certain foreign works, and the fact that different countries have different terms. PDM is not a substitute for legal advice.

A gallery applying PDM to a 19th-century painting should also check whether its own photograph of the painting attracts a separate copyright. The mark is a tool for labelling, not for creating rights. Do not use PDM on material you created yourself and intend to dedicate to the public domain; use CC0 instead, because CC0 operates as a legal waiver where PDM does not.

The Decisive Exception

The decisive exception for both tools is that neither addresses non-copyright rights. Even if a work is unquestionably in the public domain under copyright law, privacy, publicity, trademark, patent, contract and cultural-heritage laws may still control its use. A photograph of a living person may require a model release even if the photograph itself is public domain. A public-domain image of a trademarked logo may still infringe trademark law if used in a way that implies endorsement or creates confusion.

CC0's waiver and PDM's label both stop at the boundary of copyright and related rights. Check all other applicable legal regimes separately. Creative Commons states this explicitly in its FAQ: neither tool guarantees that other law permits a use.

The decision depends on who you are and what you control. If you are the copyright holder and want to dedicate your own work to the public domain, use CC0. It is the only tool that attempts to remove copyright and related-right conditions as far as you are legally able.

If you are a curator, librarian, or archivist who believes a specific work is already in the public domain, use PDM. You are not the rights holder and you are not granting permission. Your role is to label the work's status so that reusers can rely on it.

A museum that digitises a public-domain painting should apply PDM to the digital file only if the digitisation itself does not create a new copyright. In many jurisdictions, a faithful photographic reproduction of a two-dimensional public-domain work does not attract a new copyright. The rule varies. Check the law of the country where the museum is located and the law of the countries where the file will be reused.

The Safest Next Step

Preserve the source page, the exact tool and version, the date you accessed it, and any notices or exclusions displayed. Open the original source page; do not rely on a repost, search thumbnail, or platform filter alone. Record the creator, source URL, exact tool and version, displayed notices, exclusions, and the date checked. Preserve a screenshot when the use matters.

Confirm that the intended activity, sharing unchanged, adapting, using commercially, or combining, is not blocked by non-copyright rights. Check people depicted or recorded, brands, data, location or property restrictions, confidentiality, and platform rules. Attribute in a reasonable manner if the community norms of the field expect it, even though CC0 does not legally require attribution. A consolidated credits page is reasonable for many works if the work-to-credit mapping is clear and the credits remain accessible.