Velocys Inc v CompactGTL Limited, UK Patents Court, 22 September 2014,  EWHC 2951 (Pat)
This case raises some unusual issues regarding patent amendment. Velocys, an exclusive licensee, alleged infringement of two European patents, EP (UK) Nos. 1 206 508 and 1 206 509. The patents were almost identical specifications but with different claims and related to catalysts for use in the Fisher-Tropsch process.
A key feature of claim 1 of the 508 patents was a “feed stream having a residence time within said catalyst structure less than 5 seconds”. Velocys applied to amend the patent. In the amended claim “residence time” was replaced with “contact time”. Velocys also applied to make a similar amendment to the 509 patent. Unusually the grounds for the amendment was that the reference to “residence time” was an obvious mistake. Both parties were agreed on the law: unless the references to “residence time” were an obvious mistake, amending those references to “contact time” would add matter and extend the protection conferred by the patent, with the result that the patent would be invalid. To succeed Velocys therefore had to show that the skilled person would (i) immediately appreciate that the reference to “residence time” was not intended, and (ii) unequivocally ascertain that the patentee meant to refer to “contact time”.