A patent owned by Research In Motion (RIM), maker of the Blackberry personal digital assistant (PDA), has been challenged by Good Technology, a Californian start-up. Good has asked a San Francisco court to declare the patent invalid or to declare that Good is not infringing it, according to a report by the Wall Street Journal.

Earlier this month, Good announced its new “always up-to-date, cradleless system for wirelessly connecting mobile workers with valuable enterprise e-mail and data,” called GoodLink. The GoodLink application will run on a Blackberry PDA, although Good plans to launch its own hardware later this year.

A spokesman for Blackberry's Ontario-based owner recently told CNN that RIM does not consider GoodLink to be a threat. However, apparently pre-empting a patent infringement suit from RIM, Good went to court seeking a declaratory judgment to support its venture.

According to the Wall Street Journal, the lawsuit cites a meeting between Good and RIM executives in which a RIM vice president gave a verbal warning that Good was infringing RIM’s patent. The patent covers redirecting information between a host system, such as an office PC or server, and a mobile device such as a PDA while maintaining a single, existing e-mail address and mailbox.

Last May, RIM sued another rival, Glenayre, alleging infringement of its patent. Glenayre settled the case.

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