Research in Motion Ltd., maker of the BlackBerry mobile device, has countersued Visto Corp., a software company that sued RIM last week over patents on wireless e-mail.
In a filing Monday, RIM sought a declaration from federal court in Dallas that it doesn't infringe on the Visto patents. It also, in effect, asked that the issue be decided in Dallas rather than Marshall, Texas, where Visto sued RIM on Friday after winning a similar suit against rival Seven Networks Inc.
RIM is based in Waterloo, Ontario, but its U.S. headquarters is in Dallas.
"We believe the appropriate place for this to be heard is where we do business," said Jim Balsillie, RIM's chief executive.
The Visto suit threatens to draw RIM into another drawn-out legal proceeding. In March, RIM agreed to pay NTP Inc. $612.5 million to settle a four-year patent dispute. Visto was awarded $3.6 million in damages in damages from Seven, which has a countersuit pending against Visto.
Balsillie said there is clear "prior art" on Visto's patents, meaning the ideas in the patents were expressed elsewhere first.
In any case, RIM's systems are very different from Seven's, so RIM doesn't infringe on the patents, he said.
Daniel Mendez, senior vice president of intellectual property at Redwood City, Calif.-based Visto, said one of the patents at issue had stood up to examination by the patent office three times. He dismissed the notion that RIM's system was so different from Seven's as to be noninfringing.
Visto is seeking unspecified damages.
Visto also has sued other rivals. It sued Microsoft Corp. in December, claiming the latest Windows software for handheld devices infringed on three of its patents. It then filed a similar lawsuit against lesser-known rival Good Technology Inc. in January.