Not that long ago, Research In Motion was on top of the world. The handheld-device maker, based in the small university town of Waterloo, Ontario - about two hours west of Toronto in Canada - had finally settled the longstanding legal suit that was pressuring both the company's stock and its business, clearing the way for it to continue growing the market for its popular BlackBerry email devices.

At US$450 million, the settlement didn't exactly come cheap, but RIM shareholders celebrated anyway, relieved that an agreement had been signed with US-based NTP to license the company's patents on wireless email.

Shares of Research In Motion (RIM) climbed by more than 20 per cent the day the news was announced, pushing the stock price past US$80 - higher than it had been in months.

Since then, however, the stock has sagged again, falling below US$60 a few weeks ago.

The euphoria that greeted the deal with NTP soon evaporated, as the two sides failed to follow through on their agreement, with each side blaming the other for the collapse of discussions.

And now they are back in court - appearing before one of the original trial judges in the case - and there is a real chance that RIM could be hit with an injunction preventing it from selling BlackBerrys in the United States.

How did it come to this? RIM says the agreement with NTP in March was a final, binding deal that allowed it an "unfettered right" not only to use the other company's technology, but to sub-license it to others - that is, the handheld-maker's telco partners.

NTP, however, said the arrangement was simply the first stage of negotiations and that the deal had not been finalised. Research In Motion, meanwhile, might not have been quite as eager to get the deal signed as it was earlier, since the company was also busy trying to get the US Patent and Trademark Office to invalidate the NTP patents - and this campaign was starting to show some signs of success.

The Patent and Trademark Office has now issued so-called "first office" letters rejecting all six of NTP's disputed patents, something that has helped buoy RIM's share price somewhat.

However, patent experts note that such rejection letters are not uncommon when claims are being reviewed, and don't necessarily mean that the patents in question will all be invalidated.

In any case, even if there were such a decision, it could be appealed through several levels of authority, stretching the case out for years.

Analysts who follow RIM say that level of uncertainty could not only keep a lid on the company's share price, but keep potential partners away as well.