WASHINGTON (Reuters)—The maker of the BlackBerry on Wednesday gained some ground as it fights a battle over patents with NTP, which is trying to shut down most sales and service of the portable e-mail device in the United States.

The U.S. Patent and Trademark Office issued a final rejection of one of five disputed patents owned by NTP, another step in a long process that Research In Motion Ltd. hopes will allow it to keep operating its U.S. BlackBerry service.

NTP, a closely held patent holding company, has successfully sued RIM for infringement of its patents.

On Friday, the presiding judge in the case, U.S. District Court Judge James Spencer, will hold a hearing to consider NTP's request to go forward with an injunction that would shut down most sales of RIM's BlackBerry wireless e-mail device and service in the United States.

While the lawsuit has worked its way through the court system, the U.S. patent office began reexamining the validity of NTP's patents.

On Wednesday, the patent office issued a notice of its rejection.

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