Federal prosecutors have withdrawn a subpoena that asked online retailer Amazon.com Inc. to identify thousands of buyers of used books, newly unsealed court records show.

The withdrawal came after a judge ruled the customers have a First Amendment right to keep their reading habits from the government.

“The chilling effect on expressive e-commerce would frost keyboards across America” when news of the subpoena spread, U.S. Magistrate Judge Stephen Crocker wrote in a June ruling. “Well-founded or not, rumors of an Orwellian federal criminal investigation into the reading habits of Amazon’s customers could frighten countless potential customers into canceling planned online book purchases.”