Dear All,
While I am not a legal scholar by training, I have done some work in 
the area. I know of no copyright law that protects works of art for a 
longer period than (life of the author + 70 years). Some years back 
the US has extended its period of protection to this as well. It was 
then the period of protection that the EU had adopted. Before that 
protection in the US was (life of the author + 50 years). Some argue 
that this extension was due to lobbying by the Disney company (a.o.) 
as Steamboat Willey (Mickey Mouse) was due to become a figure in the 
public domain. (When the US was a net importer of works of art it 
forbid its citizens to pay royalties to foreign owners of rights in 
works of art - other countries had similar laws.)
The stipulations by the publisher at hand for the quotes, if legal, 
are bound to be based in contract law not copyright law.
Machlup some years back concluded that there was no reason he could 
think of to argue in favor of a system of copyright law if there were 
no such a law to begin with, but that since there was such a law, 
there was no reason to dismantle it either. That is about the extent 
to which support for IPR goes as far as most economists are concerned.
Best, WIlfred

Wilfred Dolfsma