The Unified Patent Court has been in operation for two years and it has had the opportunity to consider infringement by equivalents. Notwithstanding some judicial sceptical comments, there are circumstances when the prosecution history may be a powerful tool in UK infringement proceedings. Patents for Inventions, Blanco White, 5th Edition (1983 – ie, well before Actavis) records the scarcity of findings of inessential integers in UK patent infringement claims (paragraph 2-111). Prosecution historyThere are two ways in which the patent’s history might be relevant in UK infringement proceedings. First, if a patent claim has been amended, the skilled person is deemed to know that and the reason for it.