> Reducing the length of existing copyright terms might be considered an ex post facto law. Those are explicitly prohibited by the Constitution.
No, that is definitely not an ex post facto law. That's not even close to what the ex post facto law clause covers (dealing with punishments for actions that were kosher at the time they took place).
There is an argument that shortening copyrights is prohibited by the takings clause. But I think there is a very good argument that shortening them isn't prohibited by the takings clause (for the same public-private interest balance reason that led to the first amendment arguments in Eldred v. Ashcroft and Golan v. Holder failing).
No, that is definitely not an ex post facto law. That's not even close to what the ex post facto law clause covers (dealing with punishments for actions that were kosher at the time they took place).
There is an argument that shortening copyrights is prohibited by the takings clause. But I think there is a very good argument that shortening them isn't prohibited by the takings clause (for the same public-private interest balance reason that led to the first amendment arguments in Eldred v. Ashcroft and Golan v. Holder failing).