Creative Commons defines a CC0 license type (here's the full legal code) that claims to allow creators to release their works into the public domain by waiving "all their copyright and related rights in their works to the fullest extent allowed by law."

They claim in their FAQ (and the FSF confirms) that CC0 is compatible with the GPL, which is approved by the Open Source Initiative (OSI) for use with software. However, OSI has not approved CC0 and does not recommend its use as an OSS license (emphasis mine):

The most serious of the concerns raised had to do with the effects of clause 4(a), which reads: "No ... patent rights held by Affirmer are waived, abandoned, surrendered, licensed or otherwise affected by this document.". While many open source licenses simply do not mention patents, it is exceedingly rare for open source licenses to explicitly disclaim any conveyance of patent rights, and the Committee felt that approving such a license would set a dangerous precedent, and possibly even weaken patent infringement defenses available to users of software released under CC0.

I'm not sure I understand the basis for concern here (or why CC0 includes this clause to begin with, but that's another issue). I understand that you can't make someone else's patents available by putting code that utilizes those patents into the public domain, but the clause specifically refers to the "Affirmer's" patent rights (the person who decided to release the code in the first place).

What evidence is there to support the idea that using code released under CC0 would ever result in infringement of the author's own patents? I'm looking for a specific example to illustrate when and how this could ever be a problem.

  • 1
    Well, mainly, creative-commons is generally for works of art and creative media. Not code. (although some of us do view our code as works of art :P) Commented Jun 23, 2015 at 20:34
  • You seem to be mostly interested in the patents aspect, but your question title doesn't draw attention to that. Maybe reword it? Commented Jun 23, 2015 at 21:45
  • @MichaelSchumacher Well the underlying question I'm trying to answer is why CC0 wasn't approved, but I had been considering reworking the title anyway. Do you think the current revision is an improvement?
    – Air
    Commented Jun 23, 2015 at 21:55

3 Answers 3


Sparr's original answer was good, but he should have left in the bit about being sued.

The point is that the language used in CC0 constitutes a legal hazard for anyone that receives a program under CC0 and uses it in good faith.

This is the infamous patent clause of CC0:

No trademark or patent rights held by Affirmer are waived, abandoned, surrendered, licensed or otherwise affected by this document.

The typical scenario that will create a legal hazard for you is this:

  • You work on a software project (it may be open source or ARR).
  • You see some other software (typically a library) that will fit very well into your project, and you notice that it is offered under the terms of CC0.
  • You incorporate said library into your project.
  • Unknown to you, the library offered under the terms of CC0 contains patented code. The patent is owned by the Affirmer (the person that did the PD dedication, usually the initial author of the library).
  • After some time, for instance after your project has evolved into something successful and profitable - the Affirmer surfaces with his submarine-patent and demands that you pay royalities to use the library.

At this point, this patented library may be deeply integrated in your project and stopping using it may no longer be practical.

To make sure he gets paid, the Affirmer can threaten to sue you unless you pay up. Because the CC0 dedication has the quoted sentence, you're going to have a real hard time defending yourself against the Affirmer's demands in court. In all probability, your cheapest option (at least if the Affirmer is not too greedy) is to pay the patent royalties.

If you compare the CC0 with real free software licenses, such as GPLv3, you'll find this:

Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor's essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version.

Do you spot the difference?

If somebody would try to pull the submarine-patent trick with software licensed under GPLv3, it is very unlikely that they shall prevail if they sue you, as the license is designed to make such a lawsuit fail.

The point is that, if you choose to use a badly designed legal tool, which is what CC0 is, it is much easier to intimidate you by into paying royalties, than if you stick to software that provide legal immunity against this type of lawsuits.

  • The point about legal hazard is well taken, though some of the wording is unclear. What roles do "I" and "they" play in this scenario and what "gift" is being exchanged? Is the correct interpretation that I author a project, they contribute patented code to the project, I accept their pull request and they sue for royalties? I interpreted the "Affirmer" of the CC0 clause as referring to the author who releases the project, rather than to any contributor.
    – Air
    Commented Jul 29, 2015 at 21:27
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    The CC0 patent clause only applies to the Affirmer (the person that actually does the PD dedication, usually the initial author) - not to any contributor. The GPLv3 patent-license grant applies to all contributors. You've got the roles right, but the code need not enter your project through a pull request. You may stumble over it, see the CC0 dedication and think: "Just what I need for my project!" I'll try to make the language clearer. Commented Jul 29, 2015 at 21:49
  • Thanks, that is much clearer. The term "submarine patent" is also a fruitful search term that I hadn't seen previously.
    – Air
    Commented Jul 29, 2015 at 22:06
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    It seems to me that CC0 isn't so much badly designed as inappropriate for this usage. It has a very specific goal of replicating the effect of a public domain declaration in jurisdictions that don't otherwise provide for such declarations. This means it has the same problems as a public domain declaration, but that's not being "badly designed" because that was the goal of the design.
    – smithkm
    Commented Jul 26, 2019 at 18:14

Suppose that I patent an algorithm, X. Then I develop and release an implementation of that algorithm, Y. I release Y with an open source license, granting permission for others to use and distribute Y. Generally speaking, it has always been assumed that my granting of permission to use and distribute Y has also been a grant to use and distribute X. However, CC0 makes the very unusual decision to explicitly not make that grant. So, if I release Y under CC0 and you use Y in your project, then you have violated my patent rights in X.

  • Sure, in theory this sounds like what could happen. But you can sue for all sorts of things, it's a very popular means of intimidation. Doesn't mean the suit will go anywhere or that any infringement has occurred.
    – Air
    Commented Jun 23, 2015 at 22:04
  • @Air thanks, I removed the mention of suing in my answer.
    – Sparr
    Commented Jun 23, 2015 at 22:16

First off, to answer your main question, the Open Source Initative says that they did not reach a consensus and that Creative Commons withdrew their application.

In February 2012, Creative Commons submitted CC0 to the OSI for approval as an open source license, requesting that the OSI evaluate the public license fallback section, since the rest of the text is a waiver of rights rather than a license. An unexpectedly intense and detailed discussion followed — search for "CC0" and "Creative Commons Zero" in the subject headers of the February 2012 and March 2012 archives of the OSI License Review mailing list.

CC0 was not explicitly rejected, but the License Review Committee was unable to reach consensus that it should be approved, and Creative Commons eventually withdrew the application.

With that, it seems that there was discomfort for the affirmer to release information under this license that could possibly conflict with anything that was included. To make this more clear, it looks like possible legal conflicts due to the inclusion of something could potentially wind up disastrous for the affirmer, as it may be interpreted that the patent had been released into the public domain. I don't know of any examples, but this might be a fear.

  • This doesn't answer my question at all. Maybe I share some of the blame for going with a search-friendly title, but surely you noticed you're quoting the same exact FAQ article I quoted in the body?
    – Air
    Commented Jun 23, 2015 at 20:44
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    The issue is that you are asking two unrelated questions. The answer to your first (your title) is listed as my quote. I've tried to provide you with an idea to your second question, but I'm unsure of any examples or evidence.
    – Zizouz212
    Commented Jun 23, 2015 at 20:45

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