The US Patent and Trademark Office has rejected another patent owned by Research in Motion sparring partner NTP, effectively rendering invalid all eight patents RIM was judged to have infringed in whole or in part.

The USPTO's ruling was made public last week, though it's merely a preliminary judgement, not the last word on the matter. A final, categorical ruling could be some way off - the wheels of the USPTO grind exceeding slow, it seems. In June, the USPTO issued preliminary rejections of seven of eight patents that underpinned NTP's legal action against RIM, and it has yet to issue a final verdict on any of them.

The latest ruling was made after the USPTO concurred with claims that techniques detailed in the NTP patent had already been used by another company.

NTP has said all it needs to prevail is a single claim made in just one patent, and until the USPTO formally invalidates the patents it has published preliminary findings for, NTP has a case RIM must answer. No wonder RIM wants to play a waiting game, in the hope the patents NTP accuses it of infringing - and which lower and appeals courts have ruled it did infringe - cease to exist.

Alas, the judge in the case, Judge James R Spencer, last week said he wouldn't wait and nor will he force NTP to stick to the $450m settlement it negotiated with RIM in March this year.

However, the USPTO's ruling will lend weight to Judge Spencer's apparently preferred outcome: that the two companies re-negotiate a new settlement, and do so quickly. ®