Patents-how much do you need to know to sue?

How much does the owner of a method patent need to know about a competitor´s manufacturing process before bringing a patent infringement suit? Not much-according to the Court of the Appeals for the Federal Circuit (CAFC) in the recent case of Hoffman-La Roche and Syntex (Roche) v. Invamed et al. The case involved the continuing battle between name-brand and generic drug manufacturers. Roche sued eight generic drug manufacturers who were coming out with generic versions of Roche´s TICLID(R) brand anti-stroke medicine. The basic patent on TICLID(R) had expired but there were still patents on improved methods for making its active ingredient. Roche´s problem was that it could not tell from the finished product whether its patented methods had been used or not