Federal Circuit: Did you get their digits?

by Dennis Crouch

[Survey Results at the bottom]

Astrazeneca AB v. Mylan Pharmaceuticals Inc., Docket No. 21-01729 (Fed. Cir. 2022)

In December 2021, the Federal Circuit sided with the accused-infringer Mylan on claim construction of the term “0.001%” — vacating the judgment of infringement.  See Crouch, Rounding Errors in Patent Law, Patently-O (Dec 8, 2021).  Now Astrazeneca has petitioned for en banc reconsideration–seeking “consistent precedent regarding significant digits.”

The panel majority overlooked and misapprehended, by failing to cite or apply, the controlling decisions of Iwasaki and Viskase, in holding that the ordinary meaning of a numerical claim term based on significant digits may be displaced, in the absence of lexicography or disclaimer, because it may encompass more than the most preferred embodiment.

AZ En Banc Petition on Rounding Errors., citing U.S. Philips Corp. v. Iwasaki Elec. Co., 505 F.3d 1371, 1377-78 (Fed. Cir. 2007) and Viskase Corp. v. Am. Nat’l Can Co., 261 F.3d 1316, 1320 (Fed. Cir. 2001).

AZ’s patent claim is directed to formulation that includes “0.001%” PVP K25.  The case does not tell us the accused concentration, but Mylan admitted that it was within the standard rounding error, i.e., between 0.0005% and 0.0014.  The patent document does not say anything directly about how this sort of rounding should be done, and so the district court used this standard rounding error approach for a decimal with 1 significant digit. Result was a finding of infringement.  On appeal, however, the appellate majority found that the term should be given a much narrower construction.  The court’s reasoning came from its reading of the specification — in particular, the patent document provides examples comparing a concentration of 0.001% against 0.0005%. The problem is that, for rounding purposes, 0.001% is not distinct from 0.0005%.  The conclusion here is that the patent document is a bit sloppy with its use of significant digits and that led the court to its unusual decision that 0.001%  should be construed as “that precise number, with only minor variations, i.e., 0.00095% to 0.00104%.”

Figure 3 from the patent (above) provides an example of the confusion regarding significant figures.  The single chart shows effectiveness of various concentrations of PVP K25–each one at a different level of significance.  The chart particularly appears to distinguish between a concentration of 0.001% and a concentration of 0.0005%.  However, the patentee in the petition argues that 0.001% encompasses a reading of 0.0005%.

Judge Taranto dissented from the original judgment. He argued that the significant-figure convention is so well established within the scientific community that to should take much more than a stray example to shift from that basis.

I noted that the patentee-petitioner here relies heavily upon Viskase Corp. v. Am. Nat’l Can Co., 261 F.3d 1316 (Fed. Cir. 2001).  One big problem though is that the court in Viskase decided that statements from the prosecution file led the court away from the traditional rounding principles, just as the majority did in Astrazeneca.  In Viskase, the patent claimed “below about 0.91 g/cm3“, but the court interpreted the claim as “below  0.910 g/cm3” based primarily upon a prosecution history statement during patent prosecution.  The petition apparently cites Viskase as a backstop, and then suggests that its situation is totally different since it “never expressed 0.001% PVP K25 with an additional significant digit, either in the specification or prosecution history.”

= = = =

I asked Patently-O readers what range of concentrations would they see as literally infringing a hypothetical patent claiming a concentration of “0.1%” PVP K25.

12 thoughts on “Federal Circuit: Did you get their digits?

  1. 5


    What if the claim had been written to say “about 0.001%”? I generally include “about” before any number I use in a patent claim.
    I had an issue once where the spec gave a range along the lines of “about 50 degrees to 70 degrees” and the Examiner made a 112 rejection to the claim stating “about 50 degrees to about 70 degrees”. My response was that the Examiner had not shown that a person of ordinary skill in the art would have found that indefinite. The Examiner dropped the rejection in the next Office Action. No explanation.

  2. 4

    The concept of standard rounding for fractions is absurd. Here, the margin of error is 50% +/-. Looking at an article on-line re: standard rounding, for 0.015 the lower number is 0.0145 and the higher 0.0155: +/- 5%. It’s the opposite of the rule of diminishing squares: here the margin of error increases as number rounded gets smaller and smaller, yet, when squaring a fraction, rather than getting larger, the number gets smaller. From my perspective, the courts need to take this into account and apply an alternative approach where the range or rounding is the lesser of the range according to the standard rounding or a maximum %+/-, say perhaps 10% or 20%.

    1. 4.1

      The science is LESS concerned about any such “margin of error” and opts for the clear and consistent approach.

      Let’s get to the point of using basic math before we venture into any ‘new math’ scenarios, eh?

  3. 3

    Before attending law school and becoming a patent attorney, one of my myriad of jobs was teaching chemistry at both the high school and college level. At the beginning of every introductory class there was a unit dealing with significant figures, units, rounding, etc. I could never emphasize enough the importance to which these things play when trying to communicate clearly, and not just in the scientific context. This case illustrates that point perfectly. For anyone teaching anything related to a scientific topic (Dennis this is for you), this case should be Exhibit 1. Simply clarity and proper treatment of the numerical values would have avoided this problem.

  4. 2

    As to significant digits, if the fourth place was desired, 0.001% should have been written 0.0010%.

    The two numbers are different in view of significant digit treatment.

    1. 2.1

      My prior example (in the hyperlink in the write-up above) used one additional significant digit, but the same point carries here.

  5. 1

    Just a “blue pencil” comment re a reconsideration request, that “overlooked and misapprehended, by failing to cite or apply,” could have been written much more simply [and without the inconsistent and judicial-incompetence-implication of “misapprehended”] as: “did not consider”

    1. 1.1

      I disagree – “did not consider” has an appreciably different meaning than “overlooked and misapprehended”

      Difference in kind and in degree.


          Sure, “expressly did not consider them” as a surprise in the context of YOUR comment.

          The assertion though is still different in meaning – as noted, in kind and in degree.


            Who were you quoting? The phrase “did not expressly consider them” (Dennis’s comments) and “expressly did not consider them” (your comment) have different meanings.


              LOL – ah, NS II, once again WHEN you decide to chime in brings amusement, as the FACT that the two mean different things is exactly my point.

              Thanks for that.

Comments are closed.