Research in Motion, the Canadian maker of the BlackBerry wireless e-mail device, received a boost on Wednesday when the US Patent and Trademark Office issued a final rejection of another two claims at the centre of a patent infringement dispute that threatens to disrupt BlackBerry service in the US, perhaps as soon as Thursday.

US District Judge James Spencer is due to hear arguments in court on Thursday on whether he should reimpose an injunction against RIM that could force the Canadian company to shut down most US BlackBerry services. This follows a four-year legal battle between RIM and NTP, a US-based patent firm.

The Patent Office has rejected most of the nine claims contained in three separate patents although it has still to issue a final ruling on one claim. NTP can also appeal against the rulings.

“The rejections from the patent office were all based on multiple grounds, required the unanimous agreement of three senior patent examiners and are expected to withstand all future appeals by NTP,” RIM said after the ruling.

In response NTP said the review by the patent office was “the first step in the lengthy process of ‘re-examination’ ”.

Judge Spencer has made it clear that he will not delay the case, pending the patent office final rulings, and could reimpose an injunction mandated after a jury found RIM had infringed the patents owned by NTP.

The threat of a service shutdown has drawn increasing concern and criticism from RIM’s customers and legal experts who mostly argue that it should be settled through arbitration or a negotiated settlement.

On Wednesday Robert Greene Sterne, an intellectual property expert specialising in the electronics industry and who represents neither NTP nor RIM but has been following the case closely for his clients, said: “It is a mistake to assume that Judge Spencer will not shut down the Blackberry system soon after the February 24 hearing.

“RIM continues to play a dangerous game with its users and shareholders by not settling this dispute with NTP.”

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