Second, I'll agree that the relevant Constitutional passage gives a purpose clause ("..To promote the progress of science and useful arts,.."), and an operational clause: "..by securing for limited times to authors and inventors the exclusive right to their respective writings and discoveries;..".

Where I would say that both Congress and the US Supreme Court have erred in their justification for this outrage is in turning a blind eye to that all-important word included in the operational phrase: "limited". In the interpretation of the effect of this word in the meaning of the "operational phrase" to a test of the law, that is where the "purpose clause" should have been considered, if they were so idiotic as to think that "limited" just means you can keep on renewing it.

Maybe they were all victims of a Duracell commercial: they think that copyrights were meant to keep going, and going, and going...