Am I liable for copyright infringements made by a non-affiliated source? Let's say that I find a non-affiliated source that offers some creative work under a copyleft license and I decide to use that work, stating where I found it and under which license. If in the future that 3rd party gets sued for copyright infringement, can I be considered liable?
If you used some creative work of mine without my permission (I'm the copyright holder, and you have no license giving you permission) then I can sue you to make you stop using my work, to get payment for damages, and to get payment for statutory damages. If you used my work because someone else told you wrongly that you had a license, that's very unfortunate for you, but is no reason why I wouldn't or shouldn't sue you. Obviously in this situation that third party did something badly wrong. I can sue both of you together to make sure that I get payment from whoever has deeper pockets. You can also sue that third party if you think that their lying, or being mistaken, about a non-existing license caused you damages, or if there is a contract or something that makes them responsible.
If an infringement suit is filed, the plaintiff(s) would have rights of discovery. They could subpoena the source code in such a case for comparison. They could take the depositions of EvilCorp's developers and ask them about the libraries that they used. There might well be other ways to achieve the same effect.
This is likely to depend on whether Person B is aware of what Person A is doing, regardless of any imputations Person A makes as to the nature of their business. If Person B is aware, or it is found that Person B ought to have been aware, that Person A is doing something illegal, then they may be held contributorily liable for damages suffered. For instance, in (what is still) a landmark case for copyright infringement, A&amp;M Records, Inc. v. Napster, Inc., 239 F.3d 1004 (2001), Napster was found to be contributorily guilty of copyright infringement. A defense that they attempted is they weren't aware of it - which was thrown out on the basis that they should have, and could have, known that it was happening. I'm not a lawyer, but you'll need to give a lot more information about the situation for liability to be determined. Oh, and also &mdash; both of them could be held liable. It's not necessarily a case of one or the other.
The platform will get in trouble for copyright infringement. The disclaimer that you are not liable does not work, legally, since the person suing you hasn't agreed to the TOS on your webpage. You can be sued for &quot;secondary infringement&quot;, meaning that not only the uploader but also you the service provider are liable. The solution to this quandry is the &quot;DMCA safe harbor&quot;, a set of rules which, if you follow them, you won't be held liable. The specific piece of law is here. The essence of the rules is that you have to have a &quot;designated agent&quot; who receives takedown notices: if a copyright owner finds their stuff on your page, they officially notify you, then you take the material down – expeditiously (no dawdling). You notify the uploader, they either accept the takedown or file a counterclaim, you notify the rights-holder, there's a waiting period, then the rights holder can file a lawsuit, or not. If the rights-holder doesn't file suit, you can put the material back up. You cannot rely solely on the intricate DMCA notice / counter-notice dance, because under para (c)(1)(A)(ii) of §512, you also must not be &quot;aware of facts or circumstances from which infringing activity is apparent&quot;.
If you do not have permission to make and distribute reproductions of the work, then it is illegal to make and distribute reproductions of the work. US copyright law Indian copyright law
The first thing that people need to do is to quit over thinking it. That being said, I'm going to see if I can tackle your problems one by one, before summarizing and providing my own opinion: Many users don't care if their code is copied. I'm like that. I left a couple comments on Shog9's post that read this: Good point: Licensing does not prevent careless or malicious use. I'm surprised about how many people are thinking that this license will let them steal their code, because it's already happening right now. I don't want to sound pessimistic, but when thousands of people break a license/law/contract, it's a bit of a lost cause. You're not significantly damaged in a direct way, so honestly, let it go. All I want is to make sure that no one can come up to me if something of mine screwed something on there side. Aside from that, I don't care about people who don't attribute me: chances are, they have no moral sanity, and I will appreciate the people who do, and help me out. As it is, I'm 16, I share what I know with a good heart, and in a well-spirited manner, and at the end of the day, knowing that I was able to help someone out makes my day. I don't mind if my code is copied. I know that people will copy my code whether I like it or not, but I also know that there will be people in the world who will say "thanks", and will try to attribute me where possible. I feel good about that. That being said, I don't care. But the person who uses my code does. The license that affects all Stack Exchange posts are licensed under the Creative Commons Attribution Share-Alike license, or CC BY-SA. Code contributions don't fit well with this. This excellent post on Open Source explains why it's discouraged for code. What these people want is a code-friendly license, so that they can stay in the clear when it comes to copyright issues. The next thing they want, is for someone to come after them over some licensing issue. You may think that people are good, but you never know the world around you. They can be evil. For other users, they don't mind their code being copied to another post, as long as there is a link to the post and a mention of the original author. Most people post with good intention. There's not that much of an issue from a legal perspective either: The license allows people to copy and paste into answers of their own, and since the license remains the same, there's no issue to get into. The license allows it, and contributors kind of have to acknowledge it. I don't think anyone cares what happens to code that is less than 3-4 lines at least. I can probably agree. Such code probably wouldn't be eligible for copyright anyway, since it's so trivial. Many jurisdictions have a "Threshold of Originality," which means that simple things can't be under copyright. Stack Exchange does not probably want people to own the code they submit. For example, Stack Exchange has (and probably wishes to retain) the right to keep even deleted posts in the visibility of the high rep users (even if the author is against it). Wait what? You may be right that it is in Stack Exchange's interest to host content. After all, they get hits, which helps them as a business. It is illegal for companies to host illegal content. If somebody sees objectionable, copyrighted content hosted on Stack Exchange that they would like removed, then they need to file a DMCA Takedown Request. This is also why moderators, like myself, cannot process legal requests. The reason why Stack Exchange doesn't act themselves, even if they see something that is copyrighted and objectionable, is because it's a form of liability. When YouTube began removing copyrighted content themselves, they received a wave of lawsuits (If you remove some, you need to remove all. Why didn't you remove mine? being the argument). The plaintiff's won those, and when YouTube did nothing, they weren't liable at all. If a user wants to have their content taken down, it's tricky. You need to look at the Terms of Service for Stack Exchange: (quoting Section 3) You agree that all Subscriber Content that You contribute to the Network is perpetually and irrevocably licensed to Stack Exchange When Stack Exchanges gets your content, you grant them an irrevocable license to your contribution. This is pretty standard across a lot of sites: it's just a way to secure data and stay in the clear of licensing issues. At the same time, it doesn't seem fair for SE to acquire complete ownership of the content. The user must still have the final say, if the content is to be used for purposes not already agreed upon in the licence. They don't. What users have done is that they have provided a license of their content to Stack Exchange. This is done, again, through their Terms of Service: You grant Stack Exchange the perpetual and irrevocable right and license to use, copy, cache, publish, display, distribute, modify, create derivative works and store such Subscriber Content and to allow others to do so in any medium now known or hereinafter developed (“Content License”) in order to provide the Services, even if such Subscriber Content has been contributed and subsequently removed by You. The user grants a license to their content to Stack Exchange, but they do not assign or relinquish copyright. The code still belongs to them. It's important not to conflate the user contribution policy, with copyright assignment. You are still free to add an additional license to your content (known as dual or multi-licensing), and have a copy for your own use. Stack Exchange will always host a copy licensed under the CC BY-SA license. Stack Exchange can expect a high level of decorum and respect for laws from its users. At the same time, it cannot expect redundant attributions anywhere and everywhere, because one of its main aims is to not waste the users' time. Not only Stack Exchange expects it, but many copyright laws in various jurisdictions require it too. There's a concept known in many jurisdictions known as moral rights. These are rights that are irrevocable, whether you like it or not. Generally, these include attributions, disclaimer of liability, and other rights as well. Even if your work is in the public domain, you still retain these moral rights. If memory serves me right, the right to be attributed is revokable under United States copyright law. Therefore, attribution becomes more a courtesy, when the right is revoked. Licenses such as CC BY, and CC BY-SA still require attribution as a part of their licensing terms. What defines attribution is generally up to the person who uses the content. If memory serves right again, one can not demand how to attribute. There should be a clear-cut way to determine what is code and what isn't. The code formatting indicators on SE may not be adequate because some users simply use backticks, or 4-space indented text for other not-so-codey text. Personally, I feel like making the entirety of a post under both the Creative Commons license and whatever proposed code license they use is the best option, and allow people to use moral judgement to determine the most appropriate license. The concern comes about people who lack such judgment. I bet these same people don't follow the existing license anyway - and are a lost cause. We made it through! There will always be debate on the license of choice. Some people want the GPL, a license that's apparently closer to the status quo of Creative Commons license (I disagree that it's a good match), while other's want permissive licenses, such as the MIT or the Apache licenses. I'd prefer the permissive type, since it allows use in closed-source applications, and grant more rights (i.e. less restrictions) to the people that use them. I'm not going to right much because my hands are tired, but I'm sure if you've got more questions about the open source licenses themselves, you can probably ask on Open Source Stack Exchange.
Quoting content may or may not constitute copyright infringement, depending on the various factors that go into the fair use defense. Short quotes which are made for the purpose of discussion, research and commentary and not for copy would be squarely in the domain of "fair use" under US law. That means that the copyright owner would not succeed in suing you for quoting them: under the statutory mechanism for recognizing his right to his intellectual product, there is a limit on how much control he can exert over your behavior (since the two of you have not worked out some kind of agreement -- copyright law creates rights even when there is no contract). As for Facebook, you have a contract with them, embodied in the terms of service. You have been given permission to access material that they host (permission is required, under copyright law), and their permission is conditional. It says "you may access stuff on our platform only as long as you do X": if that includes a clause "don't be nasty", then that limits your right to speak freely and be as nasty as you'd like. If it says "don't quote even a little", that means you cannot quote even a little, even when you would have the statutory right to quote a little (or, to be nasty). Fair use would mean that you can't be sued for copyright infringement of the stuff that you quoted a little of. You can, however, be expelled from Facebook. You probably cannot be sued for "accessing Facebook without permission". There is a federal law against unauthorized access of computer networks, and there was a failed attempt to construe violation of a TOS as "unauthorized access" – it isn't. But accessing Facebook necessarily involves copying (that's how computers work), and there is no "fair use" defense whereby everybody has a fair use right to access Facebook. Theoretically you could be sued for copyright infringement, for accessing Facebook's intellectual property without permission. Also, Facebook can rescind your permission to access their content (see this case), and once you have been banned, it is a crime to further access their network. This assumes that there is no overriding limit on contracts that would nullify a no-quoting condition. There is no such limit on contracts in the US, so such a contract would be enforceable. There is also nothing illegal (unenforceable) about a TOS which prohibits automated methods of access.
The GPL does not explicitly specify a time within which the source code must be provided, which probably means a &quot;reasonable time&quot; is allowed. What is &quot;reasonable&quot; would eventually be evaluated by a court, if the matter ever got that far. But please note that only the copyright holder (or the holder's authorized agent) can sue for infringement. The license does not give other people a right to sue for infringement, and I doubt that any license could grant such a right. One could inform the copyright holder who could sue, but the holder need not sue, and undertaking such a suit would involve expense, time, and effort. Whether the offer to provide the source constitutes a binding agreement is not clear, and may well vary in different jurisdictions. The question does not state any particular jurisdiction.