In patent practice, there is a type of claims that often trouble applicants/patentees/inventors and patent attorneys alike — the method claims. Such claims protect a series of operational steps, and while they can directly embody the core inventive concept, they often face difficulties in obtaining evidence(s) and enforcing rights in infringement litigation. In contrast, if a method invention can be converted to a product claim, particularly by defining the product using such as parameter features, it may often achieve stronger protection.
Among the top ten reexamination and invalidation cases of 2023 in China, two cases — one involving "Polyurethane Polishing Pad"(ZL201410448504.X) and the other "Poly(arylene ether) Copolymer" (ZL200680046261.0) — both featured parameter limitations, providing an excellent lens for observation. This article will discuss the value of parameter limitations in patent drafting in light of these two cases.
