The new ruling in U.S. District Court is the latest development in an ongoing patent fight that started in 2004, when Synopsys sued Magma for patent infringement. The suit followed a warning letter from Magma that Synopsys might be infringing Magma patents. Later on, Magma developed the argument that those patents were really jointly owned by Synopsys and IBM, and that a cross-licensing agreement gives Magma the rights to any IBM EDA patent.

In early January, Magma was ordered to assign ownership of two patents to Synopsys. These were U.S. patent 6,453,446 (the '446 patent) and U.S. patent 6,725,438 (the '438 patent). Both patents address the "fixed timing" technology that Synopsys claims to have invented.

In the latest ruling, the U.S. District Court for Northern California ruled that the '446 and '438 patents are jointly owned by IBM and Synopsys. The court ruled that the ownership of U.S. patent 6,378,114 (the '114 patent) belongs solely to Synopsys.

Synopsys can no longer claim infringement on the '446 and '438 patents, said Milan Lazich, vice president of corporate marketing at Magma Design Automation. "Before the litigation began, we entered into a licensing agreement whereby we [Magma and IBM] licensed each other our EDA patents," he said. "Any patent that IBM owns, Magma has a right to use."

Lazich said Magma expects to make a motion to have infringement claims dismissed with regard to those two patents. The '114 patent, he said, is under re-examination by the patent and trademark office (PTO). The PTO, in fact, issued an initial determination rejecting all 15 of the patent's claims in August.

What if the patent is upheld? "We don't believe we infringe it in any case," said Lazich. "We'll cross that bridge when we come to it."

Magma is celebrating a bit too soon, said Brian Cabrera, general counsel at Synopsys. What's significant, he said, is that Magma cannot claim ownership over any of the patents. "We're very pleased with the results," he said. "We have the patents clear and in our name, and we can now go to the next phase of the case, which is the infringement part."

Synopsys intends to pursue infringement claims against all three patents, Cabrera said. The judge has made it clear that Synopsys can proceed without IBM's involvement, he said, and Synopsys intends to challenge Magma's patent licensing deal with IBM. "We don't believe that license is valid," he said.

As for the '114 patent, Cabrera said that re-examination is a common procedure. In fact, all three patents are under re-examination. "We're very confident our patents will come out intact," he said. The PTO did reject claims on the '114 patent, he acknowledged, but now that ownership is clear, Synopsys will have the opportunity to present its side to the PTO.

Cabrera said there is no determination yet on when the infringement phase of the trial will begin, but he said it doesn't have to wait for the re-examinations to be complete. Meanwhile, Synopsys and Magma are each suing each other for patent infringement in a separate court case in Delaware.