Protecting free software against confusing additional restrictions
The Free Software Foundation (FSF) is the steward of the family of GNU General Public Licenses (GPL), which we designed with care to ensure that copyright holders have a tool to release programs as free software in a way that perpetuates the freedom of computer users. The licenses include explicit grant of rights necessary to exercise the freedoms as defined in the Free Software Definition, clear and comprehensive obligations to provide source code, and copyleft clauses that ensure the freedoms are protected in derivative works. For over three decades, the GPLs have been at the core of the free software movement. And whenever a recipient of a GPL-licensed software sees the license, they know they have all the essential freedoms in a clear and unambiguous manner.
Unfortunately, some authors engage in confusing practices by drafting licenses using existing terms and conditions of GNU free software licenses, without the intention of granting all four freedoms to users. For example, we have long seen attempts to add restrictions to the license text itself, placed in the LICENSE file, or included elsewhere in the program's release. An example is the so-called "Commons Clause," which, when applied to a free software license, affirms that the program is covered by the license. But, at the same time, is contradicting in its meaning by asserting that selling copies of the program or implementing a commercial service with the program is prohibited.
The immediate consequence of the practice of inserting a restriction into a GNU license in this way is the confusion it causes for the community. Users still see the name of the original license, with its preamble and terms and conditions intact, transmitting a strong message that the purpose of the license is to enable users -- grant users -- their essential software freedoms. This message is clear from the license's text, and is bolstered from the renown accrued by the FSF and GNU trademarks, and their decades of free software advocacy. At the same time, these same users see a contradictory statement of the "Commons Clause," which is clearly contrary to the sprit of the free software movement and the Free Software Definition.
In the drafting process of the now current version 3 of GNU licenses, in 2007, we were already aware of practices of misleading and confusing licensing that were misusing the intent of the GNU GPLv2 by adding language that prohibited certain uses.
We wanted to empower users to remove any additional restrictions that may have been added to the license. Thus, we included this in GNU GPLv3 and AGPLv3, Section 7, titled "Additional Terms." It starts by discussing additional permissions, and then it enumerates the possible restrictions that may be added to the program after which it states the following:
All other non-permissive additional terms are considered "further restrictions" within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term.
Further explanation of this mechanism is available in the "Opinion on Additional Terms" issued during the GNU GPLv3 drafting process:
Here we were particularly concerned to address the problem of program authors who purport to license their works in a misleading and possibly self-contradictory fashion, using the GPL together with unacceptable added restrictions that would make those works non-free software.
It is important to understand that this language in Section 7, when the license is used on an actual piece of software, is a permission given by the licensor to the licensee. To make it even clearer that added restrictions are incompatible with our license, we gave users the right to delete such added restrictions and preserve the program's freedom. But we at the FSF have another legal tool against attempts to release programs under GNU General Public Licenses that have been wrongly altered to become nonfree licenses.
The FSF holds copyrights and common law trademarks to the GNU family of General Public Licenses. Moreover, the FSF holds registered trademarks for "FSF," "Free Software Foundation," and "GNU."
The FSF has always allowed everyone to use our licenses according to their intended purpose, which is to grant and protect user freedoms to run, copy, distribute, study, change, and improve the software. We are thus always happy to see more programs properly released under one of our licenses. We can't control the drafting by others of proprietary software licenses, but we can and do forbid doing this in a way that misleadingly associates those licenses with GNU or GNU licenses.
We do not allow anyone to make unauthorized derivative works of our licenses. We also do not allow and cannot accept confusing uses of the FSF's trademarks. We have allowed using the GPL's terms to create other licenses, but only under specified conditions, which are stated in our FAQ. In such cases, using GPL terms to create new licenses is permitted "provided that you call your license by another name and do not include the GPL preamble, and provided you modify the instructions-for-use at the end enough to make it clearly different in wording and not mention GNU (though the actual procedure you describe may be similar)."
Therefore, we are entitled to legally enforce our copyright and trademark for FSF licenses that have been altered by added restrictions to a verbatim GNU license. This enforcement activity is different from enforcing the GPL against redistributors infringing by not providing source code to users or otherwise releasing code that violates the GPL. In the latter case, we follow "The Principles of Community-Oriented GPL Enforcement." We work towards compliance with the GPL (and compliance with copyright law), but compliance in that case also achieves, for that program, the ethical goal of the free software movement: giving users the freedom to study, change and redistribute the software they use. This is why legal action is our last resort in GPL-compliance, and we instead focus mainly on education and assistance.
Our work of enforcing our copyright and trademark rights against those who attempt to draft proprietary licenses using our licenses unfortunately does not necessarily result in free software. We consider proprietary software unjust, but we have no legal power to prohibit drafting proprietary licenses or applying them to software one holds the copyright on. There is generally not a lot of value in investing our energy in educating and assisting the drafters when their goal is clearly to release nonfree software. Reasonably, we can only demand that the drafters cease the actions that are confusing people about the authenticity and intent of our licenses and about the programs such proprietary licenses are applied to.
Nevertheless, in confronting infringement of our free licenses, we follow similar principles of confidentiality. And similar to our other compliance efforts, we also start with carefully verifying violations. Needless to say, if it turns out that the restriction was added as a mistake, or the software developer decides to release that program as free software instead, we would be more than happy to accept the free software release and a necessary public statement as sufficient remedy to the infringement.
Proprietary software is ethically and morally wrong and we work hard to build a future that holds less and less of it. Licenses that confuse users about the freedoms they grant are damaging to the free software movement because they threaten to dilute the value and power of these licenses. When GNU licenses are misused through such confusing practices, it harms the renown accrued by the GNU project and the FSF over decades of free software advocacy. It is our duty to all computer users to stop these practices, and, if necessary, we will use our legal rights to this end.