Moved from the discussion of this answer, which makes the following claim about BSD licences:

The 3BSD licence requires (in clause 1) that your copyright notices be preserved, and that some licence text be reproduced, whenever your code is copied. But it does not require that that licence text actually apply to the copy.

However, to me that seems very unlikely to be true, for the following reasons:

  • By requiring the preservation of the specific licensing terms, without explicitly saying "those terms are to be included as a reference to the original author's licence only, but should not be taken as binding", it seems fairly clear that the BSD asserts the same licence applies to copies, with or without modification. A licence notice's language specifically asserts that a work is covered by the given licence. That is a face value reading of the notice's language. Requiring that copies carry the same language without saying it isn't binding necessarily asserts the copies are covered by the same terms, set forth by that language.
  • If it were true that copies don't need to be covered by the same licence, then the notice requirement would be trivially sidestepped by simply making a verbatim copy, then stating that it was in fact relicensed under a different license that does not carry the same requirement. Since BSD explicitly does not distinguish between copies "with or without modification", that would be perfectly within the rights given. As it's unlikely that such a reading was intended, I think better evidence is needed to support this claim.

It seems to me that in practice, when BSD-covered derived work is incorporated into code under a different licence, it isn't so much that BSD stops applying to it, as it becomes embedded in the other work, and BSD does not prohibit adding further restrictions and terms (licensing and otherwise) to the resulting work, so long as its requirement of copyright and licence notice is satisfied.

  • Before I can answer, I need to know this: when you say the words "the 3BSD licence applies to this code", do you mean "in return for the rights grant to this code as laid out in the 3BSD licence, you must obey conditions which include but are not limited to those laid out in 3BSD", or do you mean "the 3BSD licence is a complete summary of your rights to use this code and the conditions of such use"? – MadHatter Nov 13 '20 at 11:55
  • No free license allows relicensing in the United States. To offer something under a new license, you must be a specific assignee of the copyright to the work, which none of these licenses make you. When you distribute a derivative work, any elements you didn't author are necessarily distributed under the license the rightsholders to those elements offered them under because you, by law, have no power to change that. In general, any work you distribute pursuant to a license (rather than an assignment) necessarily offers each element under the license its rights holder offered it under. – David Schwartz Nov 13 '20 at 18:48
  • @DavidSchwartz I don't see a question there. Are you seeking clarification, or is that in fact an answer, and if the latter, would you prefer to write it as one? – MadHatter Nov 13 '20 at 19:51
  • @MadHatter It's neither a question nor an answer. It's explaining a possible misconception behind part of the question that is offered to help the OP to improve the question and, implicitly, a request for clarification. I suspect that the OP is just using the word "relicensed" where they actually mean something else. A statement that something is relicensed is not really a meaningful thing and I suspect the OP means something else that is just not being communicated clearly. – David Schwartz Nov 13 '20 at 20:12
  • @MadHatter: I don't know that I'm qualified to answer this, since it was your wording that "it does not require that that licence text actually apply to the copy" I have doubts about and don't think is accurate. Whatever you were referring to when you said that. It seems that the prevailing interpretation of 3BSD in the US is that it describes the necessary, but not necessarily complete conditions of anyone's use of works covered by it, so the former ("conditions which include but are not limited to those laid out in 3BSD") would be the starting point I suppose. – mathrick Nov 16 '20 at 19:56

The 3BSD licence requires (in clause 1) that your copyright notices be preserved, and that some licence text be reproduced, whenever your code is copied. But it does not require that that licence text actually apply to the copy.

I believe that this quote from @MadHatter is subtly wrong.

Yes, the 3BSD license is a permissive license that allows a recipient to redistribute a (derived) work under a license that contains additional requirements and/or restrictions on the code. But that is, as far as I can tell, not an actual re-licensing of the BSD code and the 3BSD license would still be applicable to that code, in addition to the additional requirements/constraints imposed by the other license.

Therefor, it is more correct to say that both licenses apply to the code, where redistribution has to comply with the requirements from both licenses. This is different from the code being dual-licensed, where the recipient can choose which license terms to follow.

Moreover, as the 3BSD license does not grant the right to sub-license the code, the additional requirements can only be applied in the form of a "secondary license", where that license is used for either some other part of the application or for a modification to the code and the license includes requirements that are claimed to apply to the entire codebase. This means that the secondary license is indirectly applicable to the BSD code and if you can successfully separate the two, then the additional requirements also no longer apply to the BSD code.

  • Before I write an answer, I'd like to address a semantic issue. Suppose I edit a piece of code under MIT, and publish my version under the condition that the copyright notice and permission notice be included in all copies, plus the LICENCE file must be preserved (a new condition, not part of MIT). Is that content still, in your opinion, "under the MIT licence"? In other words, when you say some content is distributed under 3BSD, do you mean "all the conditions of 3BSD apply to this content", or "all the conditions of 3BSD and no others apply to this content"? – MadHatter Nov 13 '20 at 8:12
  • @MadHatter, the MIT license is a case on its own, because it explicitly allows sub-licensing. If we ignore that aspect (or replace MIT with BSD in the first part of your comment), then I would consider the code to still be "under the MIT license", but with additional conditions applied as well. Thus when I say that content is distributed under 3BSD, I mean that "all conditions of 3BSD apply to the content" and there might be additional conditions coming from another license. – Bart van Ingen Schenau Nov 13 '20 at 8:28
  • You're right, I only chose MIT because it was less text; happy to go with 3BSD. But are you really saying that if I offered anyone a copyright licence to my work provided they retained my copyright notices and a chunk of licence text, paid me a thousand Euros, and agreed never to give a copy to anyone else, that you'd happily describe the code as "being available under the 3BSD licence"? Do you think anyone who heard you say that would expect the actual offer to be as I have described it? – MadHatter Nov 13 '20 at 11:49
  • @MadHatter, assuming the "chunk of license text" is the actual text of the 3BSD license, then I am perfectly happy to say that that copy of the code is "subject to both the 3BSD license and Agreement X", where Agreement X is what stipulates the payment and not copying further. That is what I believe happens when a paid-for, closed-source project uses.some third-party BSD-licensed code. – Bart van Ingen Schenau Nov 13 '20 at 13:07
  • That's slightly different from what you said above, which was "when I say that content is distributed under 3BSD, I mean that "all conditions of 3BSD apply to the content" and there might be additional conditions coming from another license". Now you're saying you would use a phrase other than the simple "content is distributed under 3BSD" to describe such a situation. Forgive me for pressing, but which one is it? – MadHatter Nov 13 '20 at 14:25

I think there's a semantic issue here, which may or may not mask a legal one.

When you make content available to me subject to the conditions of the unmodified 3BSD licence, then I may avail myself of most copyright-controlled rights ("Redistribution and use in source and binary forms, with or without modification"). In return, I have two obligations (the third, to retain from claiming the original author endorses my work, is a requirement that applies regardless of licence):

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

I must obey those requirements to avail myself of the specified rights. Further, I cannot give others rights I do not myself have, so when I modify the work and redistribute it, I may not fail to place those obligations on the recipient(s). I may, however, add further obligations if I so choose, as I have written elsewhere). Thus, I may convey the code to you on the conditions shown above, plus the conditions that you give me a thousand pounds and agree never to give a copy to anyone else.

The semantic issue is whether you would describe such code as "being conveyed under the 3BSD licence". If you wouldn't, as I wouldn't, then as above it's clearly permissible to take 3BSD code, modify it and convey it on, under conditions which are no longer accurately described by the 3BSD licence, so there is clearly no requirement that it should remain under the licence. If you would describe the code discussed above as still being under the 3BSD licence, then in the way you use that term I agree with you, and there's no question to answer.

The legal issue only arises if you think that the 3BSD licence requires that downstream recipients must be subject to the conditions of the the 3BSD licence and no others (that is, "subject to the 3BSD licence" as I, and others, use the term). You've indicated that you do not think that, so I'll stop here.

  • If you take some code that is under the 3BSD license (and no other terms at that point) and you include that in a project under the GPL license, how would you then characterize the license of the result if you don't have the space to reproduce the entire legal code? 3BSD is not accurate (due to the additional requirements from the GPL), but GPL is also not accurate (due to the permissible additional restrictions from the 3BSD). – Bart van Ingen Schenau Nov 17 '20 at 14:27
  • GPL. Both GPLv2 and GPLv3 make it clear that no additional restrictions to those in the GPL can apply. The FSF say that 3BSD is compatible with both, so clearly the requirement to preserve a chunk of verbatim text is not felt to be an additional restriction by the FSF, and must therefore be implicit in the condtitions applied by the GPL itself. Who am I to disagree? – MadHatter Nov 17 '20 at 14:42
  • See GPLv3 s7a to s7f for which additional restrictions are allowed. That includes "reasonable legal notices" (s7b). I couldn't quickly identify the section in the GPLv2 that prevents additional restrictions, but I expect it has similar exceptions. – Bart van Ingen Schenau Nov 17 '20 at 15:05
  • Additionally, if only the GPL terms apply, then that chunk of verbatim text has gotten the same legal status as any piece of prose and the fact that it states "don't remove me" cannot be legally enforced. Thus, I would be within my rights to remove that chunk of text if I receive that project from you. – Bart van Ingen Schenau Nov 17 '20 at 15:07
  • The analysis applies to GPLv3, but not GPLv2, which has no such similar language - only ss 5 and 6, barring redistribution if additional restrictions are imposed. I agree with your last para, but nevertheless, the FSF feel this can be done. What they don't feel can be done is have derivative works under any licence other than GPL. – MadHatter Nov 17 '20 at 15:10

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