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Choose CC0 when you hold or claim rights and want to waive them; choose the Public Domain Mark (PDM) when a work is already free of copyright worldwide and you are simply labelling that fact. The distinction is action versus assertion: CC0 actively gives up rights you control, while PDM makes no legal change — it just communicates a status. Picking the wrong one creates exactly the ambiguity open access is meant to remove.
When is CC0 the right choice?
Reach for CC0 whenever your institution created or could plausibly claim rights and wants to relinquish them: born-digital outputs, datasets, metadata, newly commissioned photography, OCR text, or 3D models. CC0 is a waiver-plus-fallback: it waives copyright and related rights (including, where possible, the sui generis database right), and where a jurisdiction forbids waiver it falls back to a maximally permissive licence. That belt-and-braces design is why CC0 works reliably across borders.
A strong signal for CC0: you are unsure whether any rights subsist, but you definitely do not want to assert them. CC0 lets you say "we claim nothing" without first having to prove the work is out of copyright.
When is the Public Domain Mark the right choice?
Use PDM only when you are confident the work is already in the public domain everywhere — typically because copyright has expired. PDM is a label, not a licence. It changes no legal status; it informs reusers. Apply it to a 1790 engraving or a 16th-century map where no copyright remains.
The catch is the phrase "everywhere". Public-domain status is jurisdiction-specific (terms differ; the US has odd publication-based rules). PDM asserts a global status that may not actually hold, which is why Creative Commons itself advises caution and many institutions prefer CC0 for digital surrogates.
How do they compare at a glance?
| Question | CC0 | Public Domain Mark |
|---|---|---|
| Legal effect | Waives rights you hold | None — pure label |
| Use when | You hold/claim rights | Copyright already expired |
| Covers database rights? | Yes, to extent possible | No |
| Safe across jurisdictions? | Yes (fallback licence) | Risky (status varies) |
| Best for | Datasets, new photos, metadata | Genuinely old originals |
| Reuser confidence | High | High if status is true |
What about the "original plus surrogate" problem?
This is the situation that trips up almost every digitisation project. The underlying work (say, an oil painting from 1820) may be public domain, but your digital photograph of it may attract a thin new copyright or related right in some jurisdictions. The clean pattern:
text
Underlying 1820 painting -> Public Domain Mark (it is genuinely PD)
Your 2025 photograph of it -> CC0 (you waive any rights in the surrogate)Expose both statements in your metadata. Many open-GLAM programmes (Rijksmuseum, the Met, and others) settled on releasing the file under CC0 precisely to sidestep arguments about whether a faithful reproduction generates new copyright.
What are the costs and downsides?
CC0 is irreversible — once waived, you cannot reclaim rights, so confirm you actually have the authority to waive (third-party content embedded in your dataset is a common blocker). PDM's cost is reputational and legal: mislabel an in-copyright work as PDM and you mislead reusers, potentially exposing them to infringement. Neither tool addresses moral rights, trademark, or privacy/personality rights, so a portrait may still carry obligations no copyright tool touches.
A simple decision procedure
text
1. Did your institution create the work or could it claim any rights?
YES -> can you/do you want to waive them? -> CC0
NO -> continue
2. Is the work definitively out of copyright in all relevant jurisdictions?
YES -> Public Domain Mark
NO -> use a RightsStatements.org statement, not PDM or CC0
3. Is there an embedded third-party right (a photo of a person, a logo)?
YES -> add a non-copyright caveat regardless of the chosen toolIf step 2 is uncertain, do not default to PDM — use an honest RightsStatements.org value instead, and revisit later.
Key Takeaways
- CC0 is an action (waiving rights you control); PDM is a statement (the work is already free).
- CC0 is jurisdiction-safe thanks to its fallback licence and covers database rights; PDM does neither.
- For digitised originals, label the underlying work PDM and the surrogate CC0.
- Many open-GLAM programmes release files under CC0 to avoid surrogate-copyright disputes.
- CC0 is irreversible — confirm you have authority to waive before applying it.
- Neither tool covers moral rights, trademark, or privacy; add caveats where those apply.
Frequently Asked Questions
What is the core difference between CC0 and the Public Domain Mark?
CC0 is a legal tool you apply to waive your own rights in something you control; the Public Domain Mark (PDM) is a label you attach to a work that is already free of copyright worldwide. CC0 is an action; PDM is a statement of fact.
Can I apply the Public Domain Mark to a photo I just took of an old painting?
No. The painting may be public domain, but your photograph might carry its own thin copyright or related rights depending on jurisdiction. If you want that photo fully free, apply CC0 to the photograph and PDM to the underlying work.
Is CC0 the same as releasing into the public domain?
Functionally close, but CC0 is more robust. Some jurisdictions do not let authors abandon copyright, so CC0 layers a fallback all-permissive licence underneath the waiver to achieve the same practical freedom everywhere.
Does PDM cover database rights or moral rights?
No. PDM only asserts that copyright has expired; it says nothing about sui generis database rights, moral rights, trademark or privacy. CC0 explicitly waives the applier's copyright and related rights including database rights to the extent possible.
Which should a museum use for its open-access image releases?
For faithful reproductions where the institution claims no new rights, many use PDM on the original plus CC0 on the digital file, or simply CC0 across the board to remove ambiguity. The key is to pick one policy and apply it consistently.