Apple could face a fine of up to $1bn if a jury rules against changes made by Apple to its iTunes and iPod software back in 2005.
10 years in the making the case argues that Apple's own digital rights management software, FairPlay, was blocking competing music services by refusing to sync them with iTunes or your iPod.
The two plaintiffs, Marianna Rosen and Melanie (Tucker) Wilson, argue that not only did the software prevent you from using rival music on Apple products but that Apple's own DRM meant you couldn't play music bought on iTunes on rival devices.
Once implemented the software update would potentially remove any music that was deemed 'dangerous' from both your iTunes and your iPod.
Apple's argued the case on the grounds that any software updates made at the time were for security.
The question the jury have to answer is whether the software update provided genuine improvements to both the product and to the customer's user experience.
If the answer to that is yes, then Apple's let off the hook. If it's no, then Apple is facing a massive $1bn fine.