"We don't expect that they'll be successful," he said. Since C2's predecessor applied for the patent in 1996, the company and the patent office both have examined its validity and not found any problems, and the service providers that C2 sued couldn't find a way to strike it down, either, he said.

EFF dismissed Weintraub's assertion.

"It's either a good patent or a bad patent," Cohn said. "It doesn't get better because you managed to squeeze money out of a bunch of people."

The questions surrounding C2's patent probably won't be resolved any time soon. The Patent and Trademark Office is likely to take action on the patent within eight to 12 months, probably rejecting some of its claims, said Nikhil Iyengar, an attorney at Fenwick & West who is representing EFF. After that the patent owner may respond by amending or canceling some of its claims, and working through that process could take another year or two, he said. If C2 files a formal appeal, it may take an additional year or two to resolve the action.