As for Luthor. Even if the actual transport is the kidnapping, Superman still holds Luthor defacto prisoner later on. Whether the legal term is kidnapping or wrongful imprisonment, or something along those lines is pretty much beside the point.

And if Luthor dies on the island due to an accident or something, it might even add manslaughter to the charges.

If we take it seriously, he has crossed a line. A jury might find him not guilty because of the merits of the case, but from a legal point of view, he could and should be prosecuted.

Could be funny, Mayson Drake could prosecute Superman and Luthor could be called as a witness.

Michael