In the class-action lawsuit, a group of consumers say Apple created a music-downloading monopoly with its iPod player and iTunes store. At issue is a piece of software called Fairplay that allowed only music bought on iTunes to be played on the iPod, according to the complaint.

One competitor, RealNetworks Inc (RNWK.O), responded in 2004 by introducing a new technology that would allow customers to play music downloaded from its site on their iPods. Apple quickly announced a software upgrade to iTunes that once more blocked music from RealNetworks, the complaint charges.

"The court finds that Jobs has unique, non-repetitive, firsthand knowledge about Apple's software updates in October 2004 that rendered the RealNetworks's digital music files once again inoperable with iPods," Judge Lloyd wrote in his ruling.

The ruling comes amid intense questions about Jobs' health and whereabouts. Earlier this month an energetic but thin Jobs resurfaced to unveil Apple's new iPad. His appearance helped reassure investors and fans worried about what his absence means for the company.

Judge Lloyd said the deposition of Jobs would be limited to questions about the back-and-forth with RealNetworks in 2004. Apple had sought to prevent the deposition altogether.

The case is in re Apple iPod iTunes antitrust litigation, Case No. 05-00037, U.S. District Court, Northern District of California.

Apple is involved in a host of other lawsuits, both as a plaintiff and defendant, ranging from disputes over patents to anti-trust allegations. On Monday, Apple sued Amazon.com Inc (AMZN.O) in a bid to stop the online retailer from improperly using its APP STORE trademark, according to a court filing. (Reporting by Paul Thomasch in New York and Sakthi Prasad in Bangalore; Editing by David Holmes and Derek Caney)