I think you mean 17-USC-108. It might surprise you to know that the web extend outside USA and that Fair Use and exemptions for libraries and archives (aside: where's the definition of those two terms in the USC that's being used here?) don't extend to the World. IA may be legal in USA but a whole lot of the websites of the world reside on servers in other countries.
There's a minor technical problem with that USC too, it seems. It allows archives to "reproduce no more than one copy of a work". But to compare a website you make a second [admittedly transient] copy to decide whether to re-archive. That's technically not within the scope of that 17USC108 accommodation AFAICT. This may have been solved in US law; I've a feeling there was a modification of EU law to allow transient/cache copies?
There's a minor technical problem with that USC too, it seems. It allows archives to "reproduce no more than one copy of a work". But to compare a website you make a second [admittedly transient] copy to decide whether to re-archive. That's technically not within the scope of that 17USC108 accommodation AFAICT. This may have been solved in US law; I've a feeling there was a modification of EU law to allow transient/cache copies?