I see this one quite a lot: an author releases something under a standard free/open license (i.e. not a crayon license), but on the same release page adds a clause that conflicts with the license. I.e.

Free Frobnicator is a handy utility that frobs widgets, by Jane Doe

Released under <license>

By the way, <additional clause that conflicts with license>

These additional clauses could be from misunderstanding the license, or carelessness. I've seen these:

  • "Let me know if you use this in your project!"

    As far as I'm aware, no free/open license requires contacting the author if you use it.

  • "Contact me if you want to use this commercially."

    Implying that the license doesn't already allow commercial use, which free/open licenses do.

  • "You are free to use however you want, except in pornography."

    Free/open licenses can't discriminate on usage.

Do these extra conflicting clauses make the license invalid, or is the license unaffected? Does it depend on the license used? Or is this legally ambiguous?

  • 6
    Or a closer example, Stack Exchange's attribution guidelines conflict with the CC BY-SA license! Commented Aug 6, 2015 at 1:27
  • 1
    @curiousdannii are you talking about this? If so, I'm not sure if it's conflicted, as the CC BY licenses give authors flexibility in choosing the manner of attribution. This may be a good separate question though. Commented Aug 6, 2015 at 5:09
  • 2
    I've asked about it at Law and will mention it when I write an answer to this question. Commented Aug 6, 2015 at 5:10
  • 1
    @curiousdannii Provided you're talking about this, it is pretty obvious that this is not in any way enforceable. But this is mainly a blog post, where Jeff Atwood airs his opinions about what he thinks should be "fair attribution". The fact that it officially linked may make it appear as something more than random opinions, but random thoughts is really all it is. IMHO, this does not even count as an attempt to tamper with the license grants of CC BY-SA. Commented Aug 6, 2015 at 6:49
  • 2
    @FreeRadical I mean this post. The SE staff at the moment appear to be treating that blog post as much more than random thoughts. Commented Aug 6, 2015 at 7:57

4 Answers 4


You are asking three questions, I think:

  1. are they enforceable?
  2. do they tamper with the enforceability of the main license?
  3. do they pollute the open/free status of the overall license?

The answer to the third question is 'yes'. If someone adds a clause that is incompatible with, for example, OSI, then it's not an OSI-licence. This has no legal implication at all. It's just a fact.

The first two questions are for lawyers, but, in general, crayons are contagious. If you scribble on a license with a crayon, the results can very possibly be crayon-ish, since by ignorance the extra provisions can conflict with or change the interpretation of the base license.


The concise, well-written answer by bmargulies does miss one thing in your question:

Does it depend on the license used?

Yes, it does. The GNU GPL, for instance, specifically says that conflicting provisions are void if they add restrictions. This is from section 7 of v.3; v.2 had the corresponding text in its section 6.

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.

Other licences that do not have such a clause may or may not be affected; I'm not a lawyer. (But it seems to me that a comment "alongside" the licence is probably meant to be part of the licencing terms, so yes, I think it'd be affected.)

  • Of course, note that if provisions in the GPL text can overrule non-GPL provisions, then vice-versa other provisions can overrule GPL provisions. The GPL does not have legal priority. Using the third example: "You are not allowed to use this software for pornography, or distribute it to people who will do so. Otherwise, you are allowed to use and distribute the program under the terms of the GPL". This explicitly states that the GPL terms does NOT have priority. To invoke section 7, the receiver must show that GPL applies, which in turns means that the "otherwise ... " condition is met.
    – MSalters
    Commented Aug 6, 2015 at 11:57
  • 2
    Nah, because anyone can distribute it again, they are void. In your example: A gets the program because he is not using it for porn or distributes it to porn people. He now has the right to give it to B with GPL attached. Only the GPL applies now to B, not the additional restriction. Now B can give the software to A to use for porn legally! The FSF lawyers are clever folks, you can't cheat their intentions that easy.
    – Josef
    Commented Aug 6, 2015 at 12:54
  • @MSalters: As I see it, either the GNU GPL applies to the program, and so the other conditions are void; or something like the GNU GPL applies (modified by your other conditions), in which case the Free Software Foundation would like a word about their copyright on the text of the GPL... Commented Aug 7, 2015 at 9:15
  • @Josef: 600 char comment limit. Of course you need to make that condition sticky like the GPL itself. That's why I summarized it as "or distribute to people who will do so" - the clause needs to be as viral as the GPL.
    – MSalters
    Commented Aug 7, 2015 at 9:24
  • 1
    @Josef: Huh. I hadn't read that entry before. I would've thought they'd be against GPL derivatives for just the reasons they describe. Anyway, I've deleted my comment as it was thoroughly incorrect, but I think this part bears repeating: "as I said in my earlier comment, I think we're a bit far afield. Either it's under the GNU GPL, or it's a crayon license and so not the situation that the question was about." Commented Aug 7, 2015 at 11:41

You say that you add this stuff on the project's "release page" (presumably the same place where people can download a release). This is not in any way enforceable. When you make free software publicly available, people can share it with anybody without ever seeing your release page, so users may not been made aware of your terms. No court is going to let you enforce any such terms.

In all jurisdictions I am aware of, including the EU and the USA, when you have a specific legal document such as a license or a contract, a court will refuse to look at anything except the specific license or a contract and any additional document specifically mentioned in the license or contract, to settle any dispute between two parties.

This means that if you put anything on the project page that conflicts with the main license, it will be considered null and void. I.e.:

  • This is not enforceable.
  • It will not tamper with the enforceability of the main license.
  • It will not even pollute the open/free status of the main license.

The same goes for a blog post written by the project head and linked from every project page. Sharing your thoughts about what you think should be "fair attribution" is fine, but it only counts as a suggestion. When staffers sometimes pretend that is more than that, such pretense does not change its legal status to being a requirement that can be enforced by legal means. I.e. such additional notes, in the shape of blog posts or otherwise, can not be enforced through courts, and will not tamper with, or pollute the main license.

I.e.: Doing this will not have any effect at all on the project's licensing situation.

However. it may identify the project head as a bozo and potentially quarrelsome (NB: I am not saying that this makes the project head a bozo, etc., only that it may make some people may think so). This may make some people stay away from using code from the project. As for the SE, the (then) project head's blog post goes on to name and shame two specific websites that does not live up his attribution expectations. This sort of enforcement technique is IMHO not an ethical way to enforce your additions to a license, but if you don't want this to happen to you, you may need to follow the SE recommendation if you reuse materials from SE, even if lacks any legal foundation.

However, some licenses such as the GPL allows additional terms. Read below the line for a more specific analysis of various ways of adding additional notices and how this applies to specific licenses.

Disclaimer: IANAL and all that.

The text above the line is my answer.

However, looking beyond the "project page" it may also be interesting to look at attempts to add additional terms to the projects distribution archive.

For instance, let us assume that you add your additional terms below the license text is the license file (e.g. LICENSE.txt) included in the distro.

If you try to add or remove anything to or from license itself, the license is no longer a recognized free software license. Doing so will make your license a crayon license (this is more or less how crayon licenses are defined), with all the problems that follows from the use of crayon licenses.

But what if you put your additional terms is a separate document? E.g. you but your terms in a file named EULA.txt, NOTICE.txt, README.txt, or some other conspicuous name) that lives in the distribution archive along with LICENSE.txt when people download the project directly from you.

Then you need to read the license text to find out whether this is permitted and if it will be enforceable. By means of example, I shall look at two popular free software licenses, GPLv3 and MIT:

  • GPLv3 very explicitly allows additional terms (see sec. 7. Additional Terms). but only if they provide additional permissions to the user, or "supplement the terms of this License with terms" [followed by a bullet list of six permitted types of additional terms]. Any other additional terms are not allowed, and permission to delete them is explicitly granted downstream recipients:

    All other non-permissive additional terms are considered “further restrictions” [...]. 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.

  • MIT/Expat grants a series of permission "without restriction". If you add terms somewhere in the distribution that contradict the license grant by imposing some restrictions, these would not be enforceable if the language used do not make it clear that the intent of the drafter was to provide a precondition or a covenant for use. If this additional document is not a license, then it will be ignored by courts (see my introduction). If it is an additional license, then, as explained in this answer it would amount to dual licensing and users would be free to pick the permissive license (MIT) that is provided over the more restrictive (the EULA).

There is no room here to run through all recognized free software licenses, but my general impression is that they do not give you much opportunity to impose restrictions on your users. I cannot completely rule out that there exists a free software license that cuts more slack than GPLv3 or MIT/Expat - but I doubt it.

However, for all free software licenses, provided you hold the sole copyright, or have permission from all contributors (e.g. through a Contributor License Agreement), adding terms that gives further permissions are generally allowed.

For instance you add a file with the following notice to a the distribution of a project licensed under MIT/Expat:

To the extent allowed by applicable law, I waive the right of attribution, and the requirement that a copyright notice and a permission notice shall be included in the program.

Such a waiver would allow people to reuse your code without having to comply with the attribution, etc. requirements of the license. If you add the following restriction to the waiver:

Removing this waiver is not allowed.

Then, that would not be enforceable, as it contradicts the main license grant.


In addition to the good answers of bmargulies and Free Radical there is a perspective beyond the legal stuff.

If you release something under an open source license, your express intent is to give others some rights, including the right to redistribute, use it without restriction and to modify and release the modified work. If you do not intent to grant these rights, you don't need to add a license at all.

But the contradicting clauses cause confusion. Especially people not experienced with the legal stuff, might be shying away from using their rights on your work. So you lose possible applications of your work against your intent. Even if you legally clearly know what you do is legally working, such confusion might lead to you losing possible users.

An example that shows how legal uncertainty lead to problems, although the reason of the legal uncertainties isn't an additional clause. The german programmer Jörg Schilling is well known as the programmer of cdrtools. At some point he decided to change the license on most of his work, while still incorporating some GPL-work. Jörg Schilling is sure, he isn't violating the GPL in this case as he expressed, and at no point any legal action happened (as far as I'm aware), this controversy didn't go to court. Still most binary Linux-distributions (source distribution is unaffected) removed cdrtools and use a fork named cdrkit. So, however the real legal situation is, the uncertainty alone lead to a lot of lost users.

So it is generally advisable to avoid confusion as much as possible.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.