"They'd do it to be first, and for all the PR," Katherine Rushton from The Bookseller magazine, said of shops not honoring an embargo from selling "Harry Potter and the Deathly Hallows" before its official July 21 release.
Bloomsbury, the book's publisher in Britain, told the BBC it had "no reason to believe anyone would want to ruin the excitement."
The publisher said it intends to "vigorously" enforce the embargo.
Embargoes on previous installments of the series generally were observed because Bloomsbury threatened to withhold future Harry Potter books from stores who thumbed their noses at the rules. Now, though, there is no such incentive.
"Because it's the final Harry Potter, Bloomsbury doesn't have that same power," says Rushton.
Even author J.K. Rowling stressed the importance of honoring the official publication date on her Web site.
"I want the readers who have, in many instances, grown up with Harry, to embark on the last adventure they will share with him without knowing where they are they going," she wrote.