According to Mentor Graphics Corporation's complaint (PDF), this lawsuit follows EVE-USA, Inc.'s declining a March 2005 offer to license U.S. Patent No. 6,876,962 (PDF). EVE is the U.S. subsidiary of Emulation and Verification Engineering, SA (France).
The '962 patent claims a tool for designing and debugging complex integrated circuits that emulates multiple circuits concurrently. An advantage to such a tool is that emulating multiple circuits simultaneously is more efficient, from a computer resource viewpoint, than emulating integrated circuit designs one at a time. Mentor Graphics alleges EVE's ZeBu Server directly infringes the '962 patent and also induces and contributes to infringement of the '962 patent. Mentor Graphics seeks injunctive relief and treble damages for EVE's alleged use of the patented integrated circuit emulation and verification technology.