The Federal Circuit recently addressed the patentability of ranges.

It is well settled law that disclosure of a genus in the prior art is not necessarily a disclosure of every species that is a member of that genus. However, there is a prima facie presumption of obviousness for overlapping ranges. The presumption exists even if the overlap in ranges is slight. This presumption may also exist if the ranges do not overlap but are “close enough.” The prima facie presumption of obviousness is rebutted if it can be shown: (1) that the prior art taught away from the claimed invention, or (2) that there are new and unexpected results relative to the prior art where the unexpected results are commensurate in scope with the claimed range.

In ClearValue, Inc. v. Pearl River Polymers, Inc., decided on February 17, 2012, the court reversed a denial of Judgment as a Matter of Law (JMOL) seeking a ruling of anticipation and found the claimed invention, which recites a clarification process for “water of raw alkalinity less than or equal to 50 ppm” by using a blend of a high molecular weight polymer and an aluminum polymer, to be anticipated by a reference that disclosed the same blend for clarifying water of “up to 150 ppm.”

The holding of ClearValue clarifies an important distinction between obviousness and anticipation. To overcome an obviousness rejection, arguments should be made, if applicable, to any teaching away or new and unexpected results of the claimed range. In contrast, where the rejection is one of anticipation, arguments should focus on instances of criticality of the narrow range as well as any evidence demonstrating differences across the range. Thus, it is also important to clearly distinguish any unique and/or critical features of a range when drafting applications having claims limited by ranges. Additional arguments, if applicable, should also be made to any lack of enablement in the prior art for the claimed range.