A study conducted by Open Source Risk Management in 2004 suggested that the Linux kernel might violate some 283 registered patents. Similarly, of the 235 patent infringements cited by Microsoft, 42 were attributed to the Linux kernel. So far, none of these patents has been litigated. But the field of software patents is so broad that Free Software advocate Bruce Perens claims that there is no software that does not violate some patent, somewhere.
Certainly, the potential risk to customers, should key software technologies in the products they invest in later be ruled to be infringing, is significant. For example, recent patent claims brought by Verizon against Vonage for its VoIP implementation could limit Vonage's ability to acquire new customers, or even to continue to operate its service. What’s important to note, however, is that Vonage's service is based on proprietary technologies, which demonstrates that there is nothing inherent in proprietary software licensing that makes proprietary products less vulnerable to patent lawsuits than open source ones.
"A particular open source license, such as the GPL, could potentially constrain the discussions to resolve a patent dispute with a patent owner," says Novell's Jones. But otherwise, he says, the risks involved with deploying either type of software are essentially the same.
The real risks
How likely is it that software patent holders will bring suit against open source customers for patent infringement? The actual risk is impossible to measure, but is probably minimal. For one thing, software patents are too pervasive. The result is a kind of patent standoff, complete with its own "mutually assured destruction" deterrent. "If we enforced all the software patents, the software industry would grind to a halt entirely," says Perens.
The recent compact between Microsoft and Novell included covenants in which each company agreed not to assert its patents against the other's customers. But despite these public commitments, it seems unlikely that either company would have pursued that course of action to begin with.
"I don't think Novell is really in the business of asserting patents against anyone," Novell’s Jones says. "We're a software company; we're a technology company. We value our customers, and so that's not something that we really even think of."
Even Microsoft is hesitant to suggest that it has any plans to sue customer companies. "If we wanted to go down that path we could have done it years ago," Microsoft’s Hauser says. "Intellectual property is the basis for collaboration between organizations, as well as a means of enforcement for rights holders. We prefer to focus on the opportunity to collaborate with others and will continue to pursue new models that address changes in the IP landscape."
MySQL's Urlocker, however, sees Microsoft's characterization of its pact with Novell as a smoke screen, designed to comfort customers with one hand while raising the specter of uncertainty around open source with the other. Furthermore, he believes the strategy isn't working. "My view is that Microsoft is trying to be divisive in the open source world, and they've been called on it," he says.