In a new lawsuit, Microsoft asks a San Francisco court to declare invalid several patents assigned to an online transactions company in hopes of defending customers who have been sued by the patent holder, WebXchange.

WebXchange earlier this year filed lawsuits against Dell, Allstate and FedEx in the U.S. District Court for the District of Delaware, charging patent infringement. The suits, filed on the same day in March, say that the companies violate WebXchange patents in some of their online services. In the FedEx suit, for example, WebXchange alleges that FedEx violates three of its patents in an online system that lets people send print jobs to Kinko's stores.

Microsoft is not mentioned in any of the three complaints. However, in the suit that Microsoft filed against WebXchange, it says that the charges relate to the companies' use of Microsoft's Visual Studio software. By asking the court to declare WebXchange's patents invalid, Microsoft hopes to defend its customers FedEx, Dell and Allstate and spare the thousands of other Visual Studio users from similar suits, Microsoft says.

FedEx, Dell and Allstate have already sought indemnification from Microsoft, Microsoft said in the lawsuit. Most large software makers like Microsoft indemnify their customers, meaning that if their products are found to cause harm including patent infringement, the software developer will bear the responsibility for the problems.

In its suit, filed in the U.S. District Court for the Northern District of California last week, Microsoft alleges that the WebXchange patents were very clearly based on existing technologies and should be invalidated.

Microsoft claims that it has tried to discuss the current disputes and any possible future suits, but WebXchange has refused.

Neither WebXchange nor Microsoft has responded immediately to requests for additional comment.

The IDG News Service is a Network World affiliate.