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Is there a size where you can copy under fair use for code you don't have a license for the purpose? For example, what if I copy a snippet that is (normally) 3 lines of code? Is that fair use? If it is fair use, what length is required before I need a license?

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Laws vary depending on where you are, and there are people here from all over the world. When asking a legal question, please tell us where you live and work. Moreover, don't trust anything we say. If it's important to you in some way (like financially), consult a local lawyer with appropriate experience. –  David Thornley Oct 15 '10 at 17:11
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2 Answers

up vote 6 down vote accepted

In the US, the legal doctrine of Fair Use does not apply to embedding excerpts of copyrighted works into source code. How such doctrine is applied by the laws of your jurisdiction may vary.

I will excerpt from a US Copyright Office article on Fair Use, and of copyrights generally:

Section 107 contains a list of the various purposes for which the reproduction of a particular work may be considered fair, such as criticism, comment, news reporting, teaching, scholarship, and research [emphasis mine]. Section 107 also sets out four factors to be considered in determining whether or not a particular use is fair:

  2. The nature of the copyrighted work

The distinction between fair use and infringement may be unclear and not easily defined. There is no specific number of words, lines, or notes [emphasis mine] that may safely be taken without permission. Acknowledging the source of the copyrighted material does not substitute for obtaining permission.

It summarizes the legal limits of copyright, which Fair Use further limits, like so:



What the limits of what copyright protects tells us is though you cannot copy "snippets" of code via Fair Use, you can rewrite the way ideas, systems (including algorithms), or factual information are expressed in those snippets.

In short, 3 lines of code should be small enough for you to rewrite it so as not to violate the original work's copyright. It probably took longer to write your question than it will to do the rewrite.

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Yes, it did take longer, but I find the question interesting =P –  Casebash Oct 15 '10 at 8:32
I don't see anything in here that says that copying a snippet of code cannot be fair use. It explains the criteria that will be used to judge whether your use is fair use, if you get sued. –  KeithB Oct 15 '10 at 16:00
@KeithB, embedding a snippet of code into another program isn't covered by Section 107, the "list of the various purposes for which the reproduction of a particular work may be considered fair." –  Huperniketes Oct 15 '10 at 17:07
The list is intended to be exemplary, not complete. That's why it contains the words "such as". If the code is largely functional, only a small section of the original work is taken, and the two works do not compete in the market, it's quite possible courts would find fair use. –  David Schwartz Sep 4 '11 at 4:00
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I am not a lawyer.

However, you are absolutely free to use the following 3 lines of code in anything that you write:

    printf("I am not a lawyer!\n");

In all seriousness, your question is quite broad and highly subjective. Ten lines of code from what? A highly specialized sorting algorithm? Some kind of firmware? One of the millions of configuration file parsers that have been floating around since the dawn of usenet?

The golden rule, really, follow the license from which the snippet came. If that is not available, use your best judgement.

I participate in several free/open source projects, some of them require a copyright assignment for anything not 'trivial'. All of them that have this requirement define 'trivial' to be ten lines of code added or modified. That is no way a substitute for competent legal advice from someone in your country, however.

My snippet gallery consists of hundreds of functions, all of them have the original author's information in doxygen style comments, as well as license info (if any, most are just public domain).

Unless clearly trivial (as in my humorous example), I would not re-use code unless I know that I have permission to do so. I also, always, follow the rules of whatever license applies.

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+1 for "Not a lawyer." –  Josh K Oct 15 '10 at 4:38
I very much doubt many snippets are in the public domain. –  Martijn Jul 23 '11 at 16:24
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