Linux vendors Red Hat and Novell are being sued for patent infringement by IP Innovation and Technology Licensing.

The plaintiffs claim they own US Patent No. 5,072,412 for a "User Interface with Multiple Workspaces for Sharing Display System Objects" issued December 10, 1991, as well as two other similar patents. It is believed to be the first patent infringement lawsuit involving Linux.

Red Hat and Novell are accused of infringing on the patents by selling the Red Hat Linux system, the Novell SUSE Linux Enterprise Desktop and the Novell SUSE Linux Enterprise Server, according to the lawsuit filed in the US District Court for the Eastern District of Texas, Marshall Division.

The plaintiffs also contend that the defendants are deliberately and willfully infringing on the patents because they were previously notified of the infringement.

IP Innovation and Technology Licensing are seeking an injunction from the court, damages, and "other relief that the court or a jury may deem just and proper," according to the lawsuit. IP Innovation is a subsidiary of The Acacia Technologies Group, a division of Acacia Research that develops, acquires, licenses and enforces patented technologies. Technology Licensing is a company that acquires and licenses intellectual property primarily in involving electronics for the television industry, according to its Web site.

Attorneys for IP Innovation and Technology Licensing could not be reached for comment.

"We're assessing this filing now," said Novell spokesman Bruce Lowry in an e-mail. "Obviously, we'll defend our interests. But it's too early at this stage to talk about specifics on this case."

Red Hat could not be reached for comment.