I'm writing an application for which I want to use some 20-year old open source code. The original code is kind of antiquated in certain aspects, for example, it's written in K&R C rather than C99; it has to manually compute certain things that are now defined in C standard library headers; there are no tests; and so on and so forth. All that the original code says by way of licensing is "Released in the public domain by so and so"; no BSD/MIT/GPL, just "public domain".

In addition to my original application, I'd like to release my own fork of the legacy library with a few of changes, chiefly to modernize it and to add unit tests. I've contacted the original author about it, but have not heard back from him. Am I within my rights to release my fork with a liberal (BSD/MIT) license? I'm not trying to make any money off of either my update of the legacy library or off of the application built on top of it.

  • This question might be more appropriate for opensource.stackexchange.com
    – David Arno
    Commented Jan 12, 2016 at 12:37
  • Usual "I'm not a lawyer" caveat applies here, but in short, if the author didn't attach a licence to the code (and "Released in the public domain" is not a licence), then they can at any stage (up until copyright expires) retrospectively apply a licence. This means that you in turn cannot apply any licence to your fork of it, as that licence could but implicitly revoked by the original author choosing to apply a licence.
    – David Arno
    Commented Jan 12, 2016 at 12:43
  • What you would be better off doing is extracting the algorithms from the original code and completely rewriting new code to fulfil them. Just so long as there's no patent issues, you can then apply any licence you like to this new code, as you will own the copyright.
    – David Arno
    Commented Jan 12, 2016 at 12:45
  • @DavidArno: this answer and the FAQ for programmers SE both say that it is the right place to ask about licensing. The algorithms in the original code get a little hairy, and I don't feel expert enough in this field to reimplement them myself. If anything, I'll try contacting the original author again. Commented Jan 12, 2016 at 17:28
  • I wasn't suggesting that this was the wrong place to ask. It's just that you can get better answers to such questions on OpenSource...
    – David Arno
    Commented Jan 12, 2016 at 18:27

1 Answer 1


IANAL but I did find an interesting piece by an IP lawyer in the US, essentially declaring that the 'public domain is not a license':

Just as there is nothing in the law that permits a person to dump personal property on a public highway, there is nothing that permits the dumping of copyrighted works into the public domain, except as happens in due course when any applicable copyrights expire. Until those copyrights expire, no mechanism is in the law by which an owner of software can simply elect to place it in the public domain.

It would appear that these caveats relate more to fear that the public-domain-ness of the work could be retracted any time by the original author.

  • I think one could reasonably argue that even in case the courts decide that releasing into the public domain is impossible, it would be interpreted as an implicit all-permissive license. But that's a question for lawyers, not programmers. Commented Jan 12, 2016 at 12:29
  • @JörgWMittag Quite right, and it will vary by jurisdiction, anyway.
    – msanford
    Commented Jan 12, 2016 at 14:21

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