During a court hearing in Oakland, California, it was unearthed that, between 2007 and 2009, Apple knowingly deleted songs downloaded from competitor music services off of iPods, the Wall Street Journal reports.

According to attorney Patrick Coughlin, when a user tried to sync tracks downloaded from another service to their iPod, iTunes would receive an error message. The message told the user they had to restore the factory settings—and when they did, the music from rival services would be deleted.

“You guys decided to give them the worst possible experience and blow up” a user’s library, Coughlin told Apple security director Augustin Farruguia, adding that the company directed iTunes “not to tell users the problem.”

The class-action lawsuit is seeking $350 million in damages, claiming Apple abused their monopoly position in digital music. If Apple is found guilty, the price tag could rise to around $1 billion under antitrust laws.

Apple's defense? According to the WSJ, “Apple contends the moves were legitimate security measures. Apple security director Augustin Farrugia testified that Apple did not offer a more detailed explanation because, “We don’t need to give users too much information,” and ‘We don’t want to confuse users.’”

The case will continue with Apple execs Eddy Cue and Phil Schiller expected to testify later this week.