In the latest twist in the five-year patent dispute between BlackBerry device maker RIM (Research in Motion) and patent-holding company NTP, the USPTO (US Patent and Trademark Office) yesterday issued a final rejection for one of the five patents in NTP's suit against RIM.

NTP can now appeal the decision to the Patent Office Board or a federal court. NTP lead counsel James Wallace of Wiley, Rein & Fielding was not available for comment. A document regarding the final rejection was posted at the Patent Office website and RIM also announced that decision in a press release. The final rejection is available here.

The dispute began in 2001, when NTP charged in a lawsuit that it owns the patents on wireless technology used in RIM's popular BlackBerry devices and server software. In August 2003, a US court awarded NTP $53.7m (about £30.8m) in damages and ordered an injunction that would prevent RIM from making, selling or servicing its devices and server software in the US. That injunction, however, was stayed while RIM appealed the decision.

While the case has continued to take several twists and turns through the courts, the USPTO has continued to review the validity of NTP's patents. The patent office has already rejected most of NTP's patents on a preliminary basis.

Meanwhile, NTP and RIM will appear tomorrow in a hearing before US District Court Judge James Spencer, who will decide whether to enforce the injunction of BlackBerry sales in the US.

RIM, however, has said that even if an injunction is enforced, it has developed software that would enable it to continue to offer its wireless email service to BlackBerry users.