Commons:Viral licenses are not automatic
Consider the following scenario:
- Alice creates and uploads a photo to Wikimedia Commons under the Creative Commons Attribution Share-Alike License (CC-BY-SA). This license requires that any derivative work be licensed under the same CC-BY-SA license.
- Bob download's Alice's work and creates a derivative work, such as isolating one of the elements of the photo and combining it with another. Bob publishes that image on his website, but does not include a notice that the derivative work is released under CC-BY-SA.
- Alice finds Bob's work based on her work. Because the CC-BY-SA on her original work requires Bob's derivative work to be licensed under CC-BY-SA, she downloads Bob's work and uploads it to Commons, attributing it correctly to Bob and tagging it with a CC-BY-SA license.
Is Alice's upload as described above permitted? The answer is no. The reason is because viral licenses are not automatic — only the copyright holder of a work can release it under a free license. If Bob has not made an explicit statement doing so, Bob's work is not available under CC-BY-SA or any other free license, and Alice's upload of his work is copyright infringement.
Free licenses are not a contract that all people who download a work agree to. They are better understood as a set of rights and obligations that a person can choose to opt in to. By opting into a license, a content reuser acquires the legal right to copy, modify, and redistribute the freely licensed work. However, they are also bound as a result by any terms or conditions contained in the license, such as CC-BY-SA's requirement that derivative works be released under CC-BY-SA.
On the other hand, a content reuser may choose to not opt in to the license. Such a person is not bound by any of the terms of the license; however they also receive none of the rights it confers, such as the right to copy, modify, and redistribute the work. These activities, which are expressly permitted for those who opt it to the license, are copyright infringement for someone who does not.
In the example above, it is possible that Bob has chosen not to opt in to the license; as such he is not bound to release his derivative work under CC-BY-SA. However, he also has no right to modify Alice's original work, and so his derivative work is a copyright infringement.
It may seem very unfair to Alice that a work she created is being exploited by someone else, and they are failing to comply with her license terms. However, using Bob's work without permission is not a legal recourse. Instead, she should follow the instructions at Commons:Enforcing license terms and ask Bob to either comply with the license by releasing his derivative work under CC-BY-SA, or cease using her work and works derived from it. If Bob complies and licenses his derivative work under CC-BY-SA, his work may then be uploaded to Commons. If he ceases to use the work, he is in compliance, and any copies Alice may retain of his derivative work still cannot be uploaded.
If Bob fails to comply, she can follow up (in the US) with a DMCA takedown notice, and eventually by suing for copyright infringement. Even if Alice successfully recovers damages from Bob and forces him to cease using her work, Bob's work still cannot be uploaded. Only the copyright holder can release the work under a free license.
Note that if Alice, the copyright holder of the original work, is either unavailable or unwilling to pursue action against Bob, there is essentially no legal recourse. A polite request to Bob to comply with the license may be effective, but he cannot be compelled to comply or to cease illegally using the work.
Just as only the copyright holder can release a work under a given license, only the copyright holder can change the license tag on a file. For example, if someone uploads a work under CC-BY and it is later discovered that it is a derivative of a CC-BY-SA work, it is a copyright infringement and must be deleted. It can only be retained if the original uploader is available and willing to change the license tag to CC-BY-SA. No one else can change it. This is unfortunate, since in many cases the uploader would have selected the correct license if they were aware of the issue at the time of upload, but if the uploader is unavailable there is no recourse other than deletion.