[DawnFalcon]

The law is this - a copy of something is only legal if you have followed all the rules when you acquired it*. If the site rules say "you may not purchase this from the UK", and you do? That copy is unauthorised. (Note that this is civil law, and it doesn't matter for there being an offence or not even if you did it inadvertently, that only affects the damages involved)

(*If those rules are legal ofc. No "jump off a cliff". But "you must be in x countries to buy it" is fine)

Legally, all that it needs is a notice on a page as to where it can be sold, further restrictions are generally due to contractual obligations on the bookstore.

Note the *purchase* is legal, the actual offence is only when you download the copy in an unauthorised location. So if you bought it from the UK using a proxy, went to America, then downloaded the book? Legal copy - AND because of first sales/exhaustion of rights, that copy is then yours legally.

If you are not thinking bad thoughts about copyright law at this point... (heh)