Open-Ended Parameter Ranges In Patent Claims – A Smart Or Risky Strategy?

An open-ended parameter range in a main claim may seem sensible to maximise the commercial value of a patent, but does this risk undermining the chances of securing grant and also patent validity in Europe?

Further to this article from Paul Andrews, here, I consider the recent European Patent Office Boards of Appeal decision T 1977/22 and offer some practice guidance on drafting patent claims in chemical sectors using open-ended parameter ranges.

Summary

Patent claims with parameter ranges are used frequently in a variety of chemical sectors, including cosmetics, metal alloys, composite materials, chemical processing/general chemical production, polymer materials, etc. A parameter range within an independent claim can be useful to establish novelty and/or inventive step: a material exhibiting a desired moisture absorbency, production of certain gas volumes from a chemical reaction, a particle with a desired surface area, a metal alloy with a desired hardness or