Does selling used textbooks hurt authors and publishers?
When you write a text book as an author according to a prescribed syllabus, you have the copy rights over the book and your publisher has the right to publish your text book as long as you permit them. However, as an author or a publisher, your ultimate objective is to disseminate knowledge among the student community, besides gaining monetary benefits by publishing and selling the text book.
It is also true that as an author of the text book, you get royalties for your text book as and when a new copy of the text book is sold.However, when a new text book is sold, neither you, as an author, nor your publisher has any right over the purchaser of your book, because the purchaser of your book, by virtue of purchasing it, becomes an exclusive owner of the book; An exclusive right over the concerned copy of the text book has passed on to the purchaser, at the time of sale of the text book.Of course, the purchaser of your text book cannot without your permission republish any part of the book, since it is a violation of your copy right as well as the publishing right of your publisher.
However,a text book once sold is meant for its usage, learning its contents and so the purchaser of your text book can lend it, gift it, sell it and take as many as xerox copies of it for his own or others usage.In short, the purchaser of a text book has unlimited usage over the text book,once he purchased it without any restrictions whatsoever.
Similarly as an author of the text book or publisher, you cannot prevent yet another author from writing a text book on the same subject and getting it published.
The only argument putforth by you as an author of the text book or your publisher is when an used text book is sold, it prevents the chances of selling yet another new copy of your text book that may fetch additional revenue to your publisher and additional royalty to you as an author.But that cannot impinge upon the right of the purchaser of your text book who has absolute and exclusive rights over the book.
Just like a car dealer cannot prevent a car owner from selling his used car to a third party, you cannot prevent a text book owner from selling his or her used text book.While there exists a number of legal formalities like name transfer, insurance coverage and transfer etc while selling over an used car, an used text book can be sold just like that, by merely handing over its possession to a purchaser.
Moreover, purchasing an used book is a cheapest option and remedy that is available to a poor student, who cannot afford to purchase a new text book.More over it is also the best way of beginning your life in a frugal way.
Therefore, selling an used text book, by no means hurt you as an author of the text book or your publisher. I can rather say that neither an author of the text book nor a publisher has any iota of legal rights over it.