Apple deleted content that iPod owners had been downloading from rival music services between 2007 and 2009, according to a report by The Wall Street Journal.
The information was released during an ongoing class action iPod lawsuit that Apple is disputing in court this week, where the Cupertino-based company is accused of having violated antitrust law by locking its iPods to the iTunes ecosystem.
A user who downloaded music from a rival music service to iTunes and then tried to sync the content to an iPod would be sent a nondescript "error" message instead. The message would advise the iPod owner to restore the device to factory settings, thus deleting any songs downloaded from a rival service and preventing it from being played, according to The Journal.
Though former Apple CEO Steve Jobs died in 2011, he is a focal point of the class-action case.
Attorneys for an estimated 8 million consumers and iPod resellers say an email sent by Jobs caused an internal campaign to keep Apple's iPods free of music that wasn't purchased from iTunes.
"We may need to change things here," Jobs said in a 2005 email that was shown to jurors in federal court on Dec. 2, according to the Associated Press.
By updating the iTunes and iPod software to block music from competing online stores, Apple kept a closed system that discouraged consumers from purchasing competing music players, plaintiffs' attorney Bonny Sweeney said this week during the opening day of the trial. This allegedly froze out rival devices, and allowed Apple to sell iPods at inflated prices.
Plaintiffs' attorney Patrick Coughlin showed jurors a 2003 email from Jobs, written about the launch of another competitor's online music store.
"We need to make sure that when Music Match launches (their store) they cannot use iPod," Jobs said in the email, according to the AP report.
The class action lawsuit is being heard in the U.S. District Court in the Northern District of California. Apple marketing head Phil Schiller and iTunes chief Eddy Cue will testify eventually during the court proceedings.