Copyright includes the right to decide whether copies will be sold at all. That right traditionally ends, for any given copy, once that copy has been sold for t

Copyright includes the right to decide whether copies will be sold at all. That right traditionally ends, for any given copy, once that copy has been sold for the first time, which is the first-sale doctrine. The quirk in this case is that it's dealing with things which had been legally sold... but not in the United States, and the doctrine is actually that the right to control sale of copies ends at the first authorized sale that occurs in the United States, not at the first sale that occurs anywhere in the world. Since the textbooks were purchased elsewhere and then imported, they had not undergone a first sale in the US, and so US first-sale doctrine had not ended the copyright holder's right to control sale.