The future of the popular BlackBerry e-mail device could rest on the outcome of a court hearing in Virginia today, as Research in Motion squares off once again with NTP Inc.

The two companies are slugging it out in a patent infringement case that dates back four years, when NTP successfully sued RIM, complaining that the BlackBerry infringed on patents owned by NTP. A jury awarded NTP US$23.1 million. Judge James Spencer later increased the damages and royalty rate RIM must pay, and issued an injunction banning BlackBerry sales in the U.S.

After a round of appeals, all of which upheld NTP's initial victory, the case is now back before Judge Spencer for review.

RIM will ask Judge Spencer to enforce an agreement reached last March in which RIM agreed to pay NTP US$450 million to settle the case. The agreement fell apart three months later.

There is a possibility Judge Spencer could order RIM to shut down BlackBerry service across the United States, the largest market for the device. However, since the BlackBerry network operates out of RIM's headquarters in Waterloo, Ont., such a ruling could raise questions about the extra-territorial application of U.S. law.