IP boutique Powell Gilbert has won its first House of Lords decision since it split from Bristows in March, clarifying the rules on patent ownership in the process.

Powell Gilbert is acting for Yeda Research and Development in its long-running battle for patent ownership against biotech companies Rhone-Poulenc Rorer and Imclone.

The patent at stake is for cancer drug Erbitux, which is worth about $400m (£194.93m) in sales each year.

“It was a case Tim Powell was working on at Bristows,” said Powell Gilbert partner Penny Gilbert. “It started out as a dispute heard before the Patent Office and has now reached the Lords: it has taken three years.”

The Lords has confirmed that anyone claiming to have part ownership of a patent must be able to prove their involvement in the development of the invention.

“The Lords has gone straight back to basics,” said Powell Gilbert partner Tim Powell. “These sorts of patent ownership issues are coming to court more often. Inventions are being made out of collaborations.”

With this point of law clarified, the Court of Appeal will hear the case again. Powell Gilbert instructed Christopher Lloyd QC, head of chambers at 11 South Square. Lloyd will move to the bench this year, which may prompt the firm to instruct a different QC when the case goes back down to the Court of Appeal.

Bird & Bird partner Trevor Cook is acting for Rhone-Poulenc Rorer, while Milbank Tweed Hadley & McCloy London partner David Perkins is advising Imclone. The two firms jointly instructed Peter Prescott QC and Daniel Alexander QC at 8 New Square.