Universal Music Group is suing a CD seller claiming that his online sales of music labeled "promotional use only" infringes on their copyrights. And the CD seller filed a countersuit this week.

The eBay seller, Troy Augusto, offers rare and collectible music, including promotional CDs. His lawyers argue that "first sale" guidelines allow him to resell the material without permission from the copyright holder.

Universal, however, claims that music labeled "promotional use only" is the company's property and can never be resold. Universal demanded that eBay take down Augusto's auctions, which are listed under the name Roast Beast Music.

In May, Universal filed a copyright infringement lawsuit. Now, Augusto is countersuing. Universal maintains in both lawsuits that Augusto does not have a right to sell promotional CDs.

The company this week told Digital Music News that the music was intended for personal use and never intended to be sold, "as is clear from the plain language on the CDs."

Augusto's lawyers said that a decision in Universal's favor could threaten library book sales, used bookstores, and stores that rent movies and video games.

Lawsuits dealing with music ownership issues are becoming common across the country. Universal and other companies in the music business increasingly pursue consumers and sellers who they claim infringe on their copyrights. The increase in litigation comes as the music business struggles to regain footing after being rocked by changes, largely because of music being downloaded over the Internet.

Last month, Universal was targeted in a lawsuit over forcing the takedown of a YouTube video that showed a child dancing to a portion of a Prince song.