I am in the habit of often specifying the license on what I write, for many reasons. This license is usually The Creative Commons license CC BY-SA. It does not create any conflict with StackExchange because that is precisely the license that is needed for StackExchange as specified in the Terms of Service. So the operation of StackExchange can in no way be disrupted by such a license on a post.

There is nothing in the Terms of Service, or anywhere that I could see, that prohibits this.

I can understand that having a license on each little bit of information can be bothersome for users of the site, and is not very meaningful anyway. Hence I am refraining from using it on smaller pieces of writing. On a larger piece, it is small enough that it is hardly noticeable.

Why do I want to do it ?

The first reason is that a lot of people will copy a document without thinking further about copyright issues. They will usually keep the license if it is there, but will not bother when it is implicit. Given that I am using a pseudo, that quickly makes an orphan work with no license on the web, which some people could appropriate through specific legislations, and I do not want that. I have no certainty that anyone, other than myself or close relatives, will want and have the right in the future to preserve open access to what I write.

The second reason is educational. It is important in the digital world that people understand the existence of licenses, and their role. It is apparent to me that users of StackExchange do not. Licenses may protect the rights and income of authors in some cases, but they may also protect works and the right of all people to access and use them. That form of awareness is socially extremely important, and scientists should more than all others be aware of it as it is crucial for their work.

Should I remind the users of this community that the open access movement is nowadays championned by the academic world in general, and is supported by the best universities and research centers in the world (including several I worked for). In addition, its origins are to be traced to the physics community and the work of physicist Paul Ginsparg who created arXiv, the first open archive, at the Los Alamos National Laboratory.

This historical role of the physics community makes it all the more worrisome to find out that many of its current members do not understand the role and effect of the appropriate use of licenses.

The last reason is simply to say thank you to people like Lawrence Lessig and the whole Creative Commons community, and indirectly to Richard M. Stallman who invented the type of licenses now used in StackExchange and many other places to preserve everyone's access to knowledge, éducation and culture.

It is customary, and even required, in the academic community to give references to the works we have been using. We do use these licenses all the time, and our work owes them more and more. It seems only fitting to mention them regularly, without abusing it on minor contributions.

Why am I saying this ?

My remarks about the fact that many members of this community do not understand the meaning and role of licenses is based on the exchange of comments when I did include a license with one or two of my posts (I do spend significant time on some). One user went so far as to edit my post to remove the license, arguing that it was controversial.

Being controversial does not seem to me a sufficient reason to erase something. Controversy is an essential ingredient of creation and advancement of knowledge. Free speech was actually an academic creation, and some universities still maintain an age-old tradition of having (now symbolic) bodyguards for people defending their doctoral dissertation, so that they can speak freely. Free speech is supposed to be the rule, unless a clear problem can be identified, to say things as loosely as possible. This was just this user's opinion against mine, and though he may be a trusted user, that is obviously not his kind of expertise.

As a matter of fact, erasing a license or any kind of copyright information from a work is generally an offense punishable by law, probably in his country, certainly in mine, in the USA and in most countries in the world. I do not mean this as any kind of threat, but only as an example of general illiteracy in those matters, which actually justifies my position above, especially in regard to education. Actually he would have a good defense, the only possible one: this is the license demanded on this site, so that he was not really changing anything. But if that is the case, why erase it ? It obviously is not controversial.

  • $\begingroup$ Of course, whatever consensus/ideas/recommendations are reached here are applicable to the entire network, so it may be worth bringing this up on Meta Stack Exchange where there is a broader user base (and more SE personnel attention). $\endgroup$ – user10851 Jul 5 '13 at 18:28
  • $\begingroup$ @ChrisWhite It occurred to me that most users on this site are scientists, and furthermore physicists. I do not write only to achieve a result, but I also value comments and opinions. Hence I considered that raising the issue here was the right place, and I still do for the moment. $\endgroup$ – babou Jul 5 '13 at 19:39
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    $\begingroup$ I disagree (-1). It makes it seem (Even if it is not supposed to) as if you don't want anyone to help spread whatever you have written. P.S. I am the user who removed the license from your post. It is not punishable by law (in any country) because your answers and questions can be edited. Something like what wikipedia says "If you do not wish your contributions to be copied and redistributed at will, please do not post it here." : ) $\endgroup$ – Abhimanyu Pallavi Sudhir Jul 6 '13 at 4:12
  • $\begingroup$ @dimension10 - Unrelated replies - Many things are not what they seem to be. - I knew you did the erasing, but that was not relevant for the discussion. - Hopefully we all do what we think is right, though most likely some of us are wrong. - I know about Wikipedia and I am a contributor. - BTW thank you for the KK comment. $\endgroup$ – babou Jul 6 '13 at 14:53

It's not that we don't understand the need for licenses.

However, there are two issues with having an explicit CC-BY-SA license on the post:

  • It's completely unnecessary. The footer mentions CC-BY-SA 3.0. The people who actually follow licenses will look for it there. The people who ignore them, well, they would ignore it anyway wherever you keep the license (of course you can put up a takedown request or ask SE to do so if you find improperly attributed material).
  • It's misleading. It gives the impression that users are allowed to specify any license they want -- this is false, all of the content must be CC-BY-SA

As a matter of fact, erasing a license or any kind of copyright information from a work is generally an offense punishable by law, probably in his country, certainly in mine, in the USA and in most countries in the world.

Except that the license wasn't erased. The license was already there, in the footer.

My remarks about the fact that many members of this community do not understand the meaning and role of licenses is based on the exchange of comments when I did include a license with one or two of my posts (I do spend significant time on some)

I assume you are basing your "fact" on this comment exchange: I (and most pobably the others) do indeed understand how licensing works, and have been using CC-BY-SA for a while now. We also know that SE already licenses all material as CC-BY-SA (3.0), so there was no need for the license blurb (and as mentioned above, it can be harmful too)

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    $\begingroup$ The other misleading part is that it suggests that the author of the post is the point of contact for licensing issues, which is just plain false. Stackexchange must attribute the authors, but the content is licensed by Stackexchange itself. If you submit a paper to a journal, even an open-access journal, you would not be in a position to say "I hereby grant others the right to use this work as follows..." or anything of the sort since you are not licensing the material to the readers. Your role in licensing ends when you turn over rights to Stackexchange. $\endgroup$ – user10851 Jul 5 '13 at 18:23
  • $\begingroup$ @ChrisWhite That sort of is point #2, however feel free to edit that in if you wish :) (Just about to reboot my laptop, may not be able to come online till I fix a few things) $\endgroup$ – Manishearth Jul 5 '13 at 18:30
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    $\begingroup$ @ChrisWhite you don't turn your rights over to Stack Exchange. SE posts are the copyright of the author and are licensed by the author to Stack Exchange under the terms of the CC-BY-SA license. $\endgroup$ – Nathaniel Jul 6 '13 at 7:14
  • $\begingroup$ (that doesn't change anything else in this thread though - it was just a technical clarification) $\endgroup$ – Nathaniel Jul 6 '13 at 7:16

As Manishearth notes, the Terms of Service are quite clear on how material on the site is licensed. If you don't want the material licensed that way then don't post it to the site.

As the copyright holder, you are obviously free to offer the material under another license if you want (the Creative Commons licenses being non-exclusive), but you don't get to do that on Stack Exchange's dime (by posting that offer on their websites); instead you should make that second offer in another venue.


Another reason for not adding your own license to post here is that it gives the impression that other posts are not similarly licensed, and that authors here get to pick their license terms. Neither of those are correct.


I wish that physics.SE users would give as much thought to the copyright of third-party content as they do to this discussion. When I flagged the embedding of a photograph protected by copyright into a post, my flag was classified as "helpful" yet the image remains.

Perhaps there should be regular reminders that only content from Wikimedia Commons (or equivalent websites if they exist) may be freely embedded into posts. For all other content protected by copyright, the right way to go about this is to put a link to the web page on which it resides. It's an inconvenience because readers then have to click on the link to view the content, but it's the only way to be sure that one does not run afoul of copyright.

"Fair Use" is probably O.K. for quoting brief excerpts of a text, but I doubt it is O.K. as a justification for embedding a photograph or illustration.

  • $\begingroup$ Thumbnails pix are fair use in the USA, but not in some European countries. Embedded links are not ok. Links to the pix itself are diputed by some. Links to be clicked to reach a page where the pix is, not the pix itself, is ok. $\endgroup$ – babou Jul 6 '13 at 20:40
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    $\begingroup$ That flag should have been declined, since moderators are not authorized to handle copyright violations. If you find something you believe to be a copyright violation, you would need to ask the copyright holder to file a DMCA request following the procedure described in the Stack Exchange Terms of Service. $\endgroup$ – David Z Jul 6 '13 at 20:41
  • $\begingroup$ @babou links are always okay, embedded images may or may not be. $\endgroup$ – David Z Jul 6 '13 at 20:42
  • $\begingroup$ @DavidZaslavsky Afaik, an embedded link, making the image look as if it came from the same site as the rest of the page, is a violation in Europe, and I would be surprised if it were not in America. If you have to click, that is considered a reference. But you may still get angry messages if you click directly the image rather than the page containing it. $\endgroup$ – babou Jul 6 '13 at 20:48
  • $\begingroup$ @babou A link does not make the image look as if it came from the same site as the rest of the page. This is a link. It is something you have to click on (so, perhaps the same thing you're calling a "reference"). Anyway, whatever you call it, it's always legal. $\endgroup$ – David Z Jul 6 '13 at 20:52
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    $\begingroup$ @David I would feel very uncomfortable "ratting out" a fellow user (who probably did not intend any harm) by alerting the copyright holder, would have preferred for this to be handled "behind the scenes". $\endgroup$ – Eugene Seidel Jul 6 '13 at 21:15
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    $\begingroup$ @Eugene Noted, but the DMCA process is legally the only method by which a copyright violation can be handled here on SE. If you don't want the copyright holder to be aware of the possible infringement, your only option is to do nothing. Keep in mind that the way it usually works is that the copyright holder files a DMCA notice, the content is removed from the site, and that's the end of it. No further consequences for the OP. $\endgroup$ – David Z Jul 6 '13 at 21:25
  • $\begingroup$ @Eugene Could I email you for some question about German copyright ? My email is babou@inbox.com $\endgroup$ – babou Jul 9 '13 at 21:18
  • $\begingroup$ Dear @babou I am sorry if I gave you the impression of being an expert on copyright law, in Germany or anywhere. I am not. You may want to try the Reference Desk on Wikipedia :) $\endgroup$ – Eugene Seidel Jul 9 '13 at 21:53

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