[CobrastanJorji]

We did see. It was the famed Eldred v. Ashcroft case. Lead counsel before the Supreme Court was Lawrence Lessig, darling of the Open Source movement. In a 7-2 ruling, the Supreme Court ruled that, so long as the time limit for copyright was in some way limited, the length of time, even if lengthened after the fact, was permissible. Justice Stephens wrote an excellent dissent, but being only one of two, was official Wrong.

[EMIRELADERO]

Ironically, that case might, at the same time, be the one who brings down the DMCA's anti-circumvention provisions.

The standard set by SCOTUS was, apart from what you've already said, that a time extension was permissible as long as the "traditional contours of copyright" were not altered. One of them was explicitly called out, fair use.

The Court also explicitly mentioned that for a regulation to survive constitutional scrutiny in regards to copyright, it must not supersede, nullify, or even "disturb" the exercise of fair use.

This set the precedent that fair use is constitutionally required, not only a generous grant by Congress.