The US Patent and Trademark Office has rejected a patent that it had previously awarded to NTP and that is central to the ongoing litigation the company is taking against BlackBerry-maker Research In Motion (RIM).

The USPTO rejected all claims in the patent, including five of the seven claims that last year a court ruled RIM infringed, RIM said. The move follows an initial rejection ruling on the patent made in September by the USPTO.

NTP, the company suing RIM for patent infringement, will have a chance to appeal the new ruling but won't be able to submit additional information for consideration by the USPTO, RIM said.

The USPTO's ruling marks an unusual twist in the long-running lawsuit. The Court of Appeals for the Federal Circuit has already decided that RIM has infringed on the patents, which now the patent office says it awarded mistakenly. But because the patent review process and the legal proceedings happen independently of each other, it's not known yet how the patent rejection could affect RIM's future. In late February, a judge will consider a request by NTP to order RIM to shut down its service in the US, based on the previous patent infringement ruling against RIM.

RIM said it believes that the USPTO will quickly continue to re-examine the rest of NTP's patents, all of which have been rejected by the USPTO in at least initial rulings.

RIM's BlackBerry devices are used by workers around the globe to wirelessly send and receive corporate e-mail. Many companies are reported to be ready to ditch the device if the service is interrupted, although RIM has promised a patch that will avoid patent problems and keep the service online.

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