Actually, it applies if you bought the book in the US as well. If a book is printed outside the US, but holds a US copyright, no matter who sells it in the US, that person potentially must get consent from the copyright holder.
So, let's say you bought a book at a yard sale. Let's say it is a German translation of a US work, so the copyright is US, but the book was printed in Germany 25 years ago. It has been through numerous resales. You are still potentially in violation if you sell that book on Ebay.
In a way Made in USA vs Made in China is the question.
I'll give you an example of a book I now have in my lap.
It is a children's book. The author holds the copyright. The book was published by Houghton Mifflin, NYC. BUT, the book was printed in China.
As it stands now, Houghton Mifflin or any bookstore, Amazon, or myself, if I wanted to sell it on Ebay, would have to get permission from the author or risk being in violation.
However, if that book had been printed in the US, then there'd be no problem.
So the question that faced the judges was... since author and publisher are in the US, does that make it a legal product of the US under US law... or because it was printed in China, does that make it a product of China?
The ruling was that it's a product of China.
That's a bummer for the publishing company. Maybe they'll bring their printing back to the US. On the other hand, if the publishing company held the copyright rather than the author, then it would theoretically benefit the publishers because they could rake in money from the resale businesses.