Patent claims, previously definite pre-Nautilus, are now indefinite post-Nautilus

Nicolas Seckel | September 17, 2015

The Dow Chemical Co. v. Nova Chemicals Corp. (Precedential)

August 28, 2015

Before: Prost, Dyk (author), Wallach

This decision dispels any doubt that the Supreme Court changed the law of definiteness in its decision Nautilus Inv. v. Biosig Instruments, Inc. (2014).
In 2012, under the pre-Nautilus standard (patent claim is indefinite if “not amenable to construction” or “insolubly ambiguous”), the Federal Circuit had affirmed a jury verdict of infringement and no invalidity, including no indefiniteness.
This time, under the Nautilus standard (patent claim is indefinite if “fail[ing] to inform, with reasonable certainty, those skilled in the art about the scope of the invention”), the Federal Circuit reverses an award of supplemental damages in the same case, because the same patent claims are now held indefinite.

Dow sued Nova for infringement of a group of patents directed to ethylene polymer compositions having improved tear strength so they can be used to make thinner films. In the District Court, a jury found the patents infringed and not invalid, including no indefiniteness. The Federal Circuit affirmed. The case was remanded for a trial on supplemental damages, and the District Court awarded supplemental damages (for infringement acts after filing of the complaint). Nova appealed again.
Representative claim recitation:

(iii) a melt index (I2) from about 0.001 grams/10 minutes (g/10min) to about 10 g/10 min,

(iv) no high density fraction,

(v) a single melting peak as measured using differential scanning calorimetry, and

(vi) a slope of strain hardening coefficient [SHC] greater than or equal to 1.3; and…


SHC = (slope of strain hardening)*(I2)0.25


FIG. 1 shows the various stages of the stress/strain curve used to calculate the slope of strain hardening…


No corresponding Figure in the patents

Figure submitted to the Court (color annotations added to show the relevant curve portion):

Unchallenged testimony by Dow expert:

It was known that the maximum slope should be measured.

Trial record: four available methods for measuring slope:

– 10% secant tangent method
– Final slope method
– Most linear method
– Dow expert’s “fifty-data-points linear regression” method

CAFC in earlier decision (pre-Nautilus): “the mere fact that the slope may be measured in more than one way does not make the claims of the patent invalid.”

CAFC in this decision (post-Nautilus): “[t]he claims are even more clearly indefinite than those in Teva” (Teva Pharm. USA, Inc. v. Sandoz, Inc. (Fed. Cir. 2015), where “the patentee’s expert… testified that someone skilled in the art could determine which method was the most appropriate” to calculate a “molecular weight” among peak average Mp, number average Mn, and weight average Mw). Here, the patentee’s expert made up his own slope measurement method.


After Teva, this decision provides another clear “data point” regarding indefiniteness. When a claim element relies on a measurement or evaluation, the description of the patent should explain in details and in a consistent manner how the measurement or evaluation is to be performed, and prosecutors should be careful to maintain this consistency throughout the prosecution record.

Full opinion

Subscribe | 登録



词典 / 辞書 / 사전
  • dictionary
  • dictionary
  • 英語から日本語

Double click on any word on the page or type a word:

Powered by