As arguments began in the hearing that will decide the fate of Research In Motion's BlackBerry service, the U.S. Patent and Trademark Office said Friday that it had ruled the second of five patents at the heart of the patent infringement case invalid in a final judgment.

The news means that only three patents remain viable in the case, all of which have already been ruled invalid in non-final actions. The latest move by the USPTO gives RIM even more ground to stand upon in asking the judge to either stay or dismiss the injunction.

In comments to eWeek, the patent office said it had no timetable for final decisions on the remaining three patents. Based on the agency's actions this week, however, it appears as if it is moving quickly to bring the first phase of the review process to a close.

In its opening arguments at the hearing Friday, NTP said it was entitled to a larger settlement due to the increasing popularity of the BlackBerry device. Meanwhile, RIM urged the court to hold a new trial, saying the USPTO's rejection of NTP patents has substantially changed the case.

It is not clear how U.S. District Judge James Spencer will rule, although he has indicated he'd like to see the case come to a close. Spencer has been handling the NTP-RIM battle for the past three years.

But even with the positive results for RIM, Spencer has previous said he would not wait for the Patent Office to finish the reexamination process. Experts say that process may not be completed until October, and NTP notes it will challenge any decision not in its favor through the federal court system.