[stubish]

Everyone is happily using public domain software in all jurisdictions. The timezone code used by many (all?) Linux and Unix distributions is public domain.

If you can find a jurisdiction without the explicit concept of the public domain and judges and lawyers that think there is no implicit concept of the public domain and someone who can claim copyright with a straight face to code that explicitly states that the authors relinquish their claim, then I still suspect it would get thrown out of court and the claimant opening themselves to charges of criminal fraud (entrapment and extortion) or abusing the justice system for profit.

[fanf2]

The reason it would fail in court is estoppel. https://en.wikipedia.org/wiki/Estoppel

[GlitchMr]

Entrapment can only be committed by government agents.