Martin Howe QC andHenry Ward represented MMI Research Limited, the respondents of an appeal in relation to the validity of a patent for ‘IMSI catchers’ which are devices used by the police to ascertain the mobile phones numbers of suspected criminals etc. The main issue was whether or not it was obvious to provide a new LAC (location area code) in order to catch the ISMIs. At first instance the trial judge held that the patent was valid and infringed. The Defendants, Cellxion Ltd, appealed. The appeal was allowed on the basis that the expert evidence showed that a skilled team would have known that a new LAC was needed when working out how to use a virtual base station to capture IMSIs.