Anybody under U.S. jurisdiction can follow U.S. law.
However if me and my company and everything is in Europe and I use/redistribute the code in Europe I must follow applicable European law. If that doesn't accept that form of public domain the author (rights owner) could sue me and it were upon the judge, who sensible they are. (This is mostly theoretical - if the author decides to put it in public domain per U.S. law they most likely don't want to restrict to U.S.)
> If that doesn't accept that form of public domain the author (rights owner) could sue me and it were upon the judge, who sensible they are. (This is mostly theoretical - if the author decides to put it in public domain per U.S. law they most likely don't want to restrict to U.S.)
Generally speaking, the risk is less the author themselves (though they could always do an about-face for whatever reason, it's hardly unprecedented[0]) and more eventual heirs of them who could always decide to cash in.
That was a completely different situation. In that case, the material was still under copyright in Germany. In this case, the material has been placed in the PD by the original author and so no one in the world can possibly have any legal claim on it.
But if this really concerns you, I would be happy to provide you -- or anyone else -- with a licensed copy of any of DJB's code for a modest processing fee.
> In that case, the material was still under copyright in Germany.
Which is exactly the case of djb's work here.
> In this case, the material has been placed in the PD by the original author and so no one in the world can possibly have any legal claim on it.
Wrong. djb and any possible heir of his does, because you can't place things in the public domain in mainland europe.
> But if this really concerns you, I would be happy to provide you -- or anyone else -- with a licensed copy of any of DJB's code for a modest processing fee.
Unless djb specifically gave you license to do so, your "licensed copy" is worth exactly as much as the original public domain dedication is. As far as european law is concerned, you have no rights to the work, and thus certainly don't have the rights to relicense it.
That is true, but there currently is no precedent for that. Until someone becomes the "sacrificial lamb" by 1. taking the risk and 2. being sued for it, anyone intending to build a business is understandably wary and unlikely to touch public-domain-dedicated assets.
However if me and my company and everything is in Europe and I use/redistribute the code in Europe I must follow applicable European law. If that doesn't accept that form of public domain the author (rights owner) could sue me and it were upon the judge, who sensible they are. (This is mostly theoretical - if the author decides to put it in public domain per U.S. law they most likely don't want to restrict to U.S.)
For an example see the recent case about project Gutenberg https://news.ycombinator.com/item?id=16511038