A Range With No Special Features Can Anticipate Sub-range

February 17, 2012

What This Means To You

  • When patenting a sub-range (a narrower claimed range within a broader range) of a prior art range, clearly articulate any special features about the sub-range in the application.
  • You may be able to overcome an anticipation rejection of a sub-range by making an argument that the sub-range was non-obvious over the alleged anticipatory range.
  • When trying to invalidate a claim containing a sub-range of a prior art range, argue both anticipation and obviousness.


In patent law, a range of values is treated as a genus. While it is established that under some circumstances a genus can anticipate a species within the genus, it has been less clear whether a genus can anticipate a sub-genus.

The US Court of Appeals for the Federal Circuit (Federal Circuit) previously held in Atofina v. Great Lakes Chemical Corp. that a prior art range does not anticipate a later claimed sub-range, if the sub-range exhibits an unexpected quality relevant to the practice of the claimed invention.

Now, in ClearValue, Inc. v Pearl River Polymers, Inc., the Federal Circuit has found a sub-range anticipated by a prior art range based on a lack of any considerable differences between the two.

Case Background

ClearValue and Pearl River are both distributors of agents for water purification. ClearValue sued Pearl River for indirect infringement of one of ClearValue’s patents.

Pearl River argued that the claims in the asserted patent were anticipated by a piece of prior art disclosing the same process for water purification as the claims in the patent. The only difference between the claims in the ClearValue patent and the prior art was the prior art disclosed that the process works with water of a raw alkalinity of 150 ppm or less, while the patent claimed the sub-range of 50 ppm or less.

After a jury found ClearValue’s patent to be valid and indirectly infringed, the district court denied Pearl River's motions for judgment as a matter of law (JMOL) of invalidity and noninfringement. Pearl River appealed to the Federal Circuit which reversed the district court.

Decision Analysis

At the Federal Circuit, Pearl River argued that the sub-range of the ClearValue patent was anticipated by the disclosure of the larger range in the prior art. ClearValue tried to rebut by arguing that the prior art disclosure as a whole was “teaching away” from the claimed sub-range.

However, the Federal Circuit held that “teaching away” is relevant to obviousness, but not to anticipation. The court then analyzed whether or not the prior art range anticipated the claimed sub-range, citing its earlier Atofina decision in which a prior art temperature range for a chemical synthesis process was found to not anticipate a later-claimed, fully encompassed sub-range, because the specific sub-range was critical for the synthesis process to work.

In Atofina, the court made it clear that a range of values is viewed as a genus, not as a disclosure of each and every value or sub-range within that genus. It further stated that a later claimed sub-range is only anticipated by a prior art range if the sub-range is described with sufficient specificity and if there are no considerable differences between the prior art range and the later claimed sub-range.

The court distinguished the ClearValue facts from Atofina and found the prior art range of 50 ppm or less in the ClearValue patent anticipated, because there was no evidence that the sub-range was in any way critical for the claimed water purification process, or otherwise considerably different from the prior art range of 150 ppm or less.

With the Atofina and ClearValue decisions, the Federal Circuit has expanded the anticipation analysis in the context of ranges to include factors that are typically found in an obviousness analysis, i.e. whether or not a sub-range possesses any unexpected, special characteristic as compared to a prior art range. However, the court refused to consider another obviousness-type factor, that of a teaching-away, in its anticipation analysis.


When a prior art range overlaps or encompasses a later claimed sub-range, evidence of criticality or of a considerable difference between the two ranges impacts the determination of both obviousness and anticipation of the sub-range. Based on the ClearValue and Atofina cases, it is possible to defend against an allegation of anticipation by showing the criticality of the sub-range. Any known critical features distinguishing a sub-range should be clearly articulated when claiming the sub-range.

The use of obviousness-type arguments in determining anticipation may extend beyond ranges of values and might apply to other scenarios involving a prior art genus and a later-claimed sub-genus as well.