Blackberry maker Research in Motion was dealt another legal setback this week, which could force the company to close its mobile email service in America.

A US District Judge in Richmond, Virginia, rejected RIM's request to delay the case and refused to enforce a disputed, $450 million settlement with patent holder NTP Inc.

"Valid patents would be rendered meaningless if an infringing party were allowed to circumvent the patents' enforcement by incessantly delaying and prolonging court proceedings, which have already resulted in a finding of infringement". Spencer said in his ruling from Richmond, VA.

During the upcoming proceedings, the District Court will be asked to decide a variety of matters relating to the litigation, including the impact of the Federal Circuit's reversal of infringement findings on issues of liability and damages.

RIM said it also expects NTP to ask the District Court to enter a new injunction prohibiting RIM from providing BlackBerry service and from using, selling, manufacturing or importing its handhelds and software in the United States.

The District Court will schedule briefings and a hearing prior to deciding each of these matters. RIM maintains that an injunction is inappropriate given the specific facts of this case.

RIM has said though that it has been preparing software workaround designs which it intends to implement if necessary to maintain the operation of BlackBerry services in the United States.

RIM has said that further details will be made available if such implementation becomes necessary.

The court battle between the two companies has been raging on since 2003.