(April 26, 2024) - Venable attorney Donald H. Heckenberg Jr. explains how the standard for determining whether a patent is invalid as indefinite has been applied in varied contexts.
Ten years have passed since the Supreme Court's decision in Nautilus, Inc. v. Biosig Instruments, Inc. establishing the reasonable certainty test for determining whether patent claims are indefinite under 35 U.S.C.A. § 112.1
Many thought immediately following the Nautilus decision that the reasonable certainty test would result in patent claims being found invalid more often than under the previous test for indefiniteness. But cases from the U.S. Court of Appeals for the Federal Circuit show that reasonable certainty is not as high of a bar as may have been thought; exacting precision in claim terminology is not required under the Nautilus test.
In Nautilus, the Supreme Court rejected the previous test set forth by the Federal Circuit for determining indefiniteness under Section 112. The Federal Circuit's test had looked to whether claim terms were "amenable to construction," and whether claims, as construed, were not "insolubly ambiguous." The Supreme Court found that the Federal Circuit's standards did not satisfy the requirement under Section 112 that claim terminology be precise enough to afford clear notice of what is claimed.
To ensure the necessary precision, the Court held that "a patent is invalid for indefiniteness if its claims, read in light of the specification delineating the patent, and the prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention."2
The Supreme Court therefore envisioned the reasonable certainty test as requiring more clarity in claim terminology. And, indeed, the Federal Circuit subsequently characterized reasonable certainty as being a "more stringent" standard than its previous test.3
A recent search found 88 Federal Circuit cases since Nautilus that have discussed and applied the reasonable certainty test. Often the court has found claims to be indefinite under Section 112 under the test. But the Federal Circuit has almost as often found non-exacting claim terminology to pass muster under Section 112.
Such cases are consistent with the Court's instruction in Nautilus that while claim terms must be precise, "absolute precision is unattainable."4 As evidenced by the cases discussed below, a key question when evaluating the reasonable certainty of a claim term is whether the intrinsic evidence of the patent, i.e., the patent specification, claims, and prosecution history before the U.S. Patent & Trademark Office (USPTO), provides guidance such that one of ordinary skill in the art would understand the scope of the claim. With such guidance, inexact claim terminology can survive post-Nautilus.
The permissiveness of the Federal Circuit under the reasonable certainty standard can be seen in its cases where terms of degree are held to not be indefinite. Common examples of terms of degree often found in patent claims are "substantially," "about," "close," and "near."
Generally speaking, patent drafters like to use such terms because they may provide for a broader claim scope than more exacting terminology. Indeed, the Federal Circuit has recognized that "descriptive words (or terms of degree) in a claim may inherently result in broader claim scope than a claim defined with mathematical precision ... [b]ut a claim is not indefinite just because it is broad."5
An example of the court finding that terms of degree are permissible is Exmark Mfg. Co. v. Briggs & Stratton Power Prods. Group LLC.6 In this case, the Federal Circuit rejected an argument that a claimed "elongated and substantially straight" baffle portion in a lawn mower was indefinite.
The Court noted that while the defendant "seeks to impose a strict requirement of how straight the baffle portions must be, no such numerical precision is required using such terms of degree."7 In its analysis, the Court found that further claim terminology directed to the functionality of the baffle portions informed what was meant by "substantially straight," while noting that functional language can promote definiteness because it helps bound the scope of the claims by specifying the operations that the claimed invention must undertake.8
Guangdong Alison Hi-Tech Co. v. ITC is another example of the Federal Circuit finding that terms of degree are permissible under the Nautilus test.9 Here, the relative term "lofty" was used in the claims at issue in the context of a "lofty batting," which is a fibrous material used as a reinforcement in aerogel composites.
Alison argued that the term does not have a precise boundary and that the claims were therefore invalid. The Federal Circuit agreed that a lofty batting is a term of degree but found that the Alison was seeking a level of "mathematical precision" beyond what is required under the reasonable certainty test.10
The court then noted that the specification of the patent provided express definitions for "lofty" and "batting," and that the written description also provided details of the functional characteristics of a lofty batting. The court concluded that examples and procedures provided sufficient guidance and points of comparison such that the scope of a lofty batting was reasonably certain to one of ordinary skill in the art.
To be sure, some Federal Circuit cases have found terms of degree to be indefinite, particularly where the court finds that the terms are purely subjective and there are no objective boundaries set forth in the patent specification and prosecution history.11 But, as Exmark and Guangdong Alison demonstrate, terms of degree can be acceptable under the Nautilus reasonable certainty test.
The possibility of multiple interpretations of claim terminology is another common issue often argued in the context of indefiniteness. The Court in Nautilus stated that a claim term might be indefinite if its language "might mean several different things and no informed and confident choice is available among the contending definitions."12
Yet, the Federal Circuit has found that the mere fact that a claim term is susceptible to different interpretations does not necessarily mean that the claim term is indefinite under the reasonable certainty test.
Clearone, Inc. v. Shure Acquisition Holdings, Inc., illustrates the Federal Circuit's acceptance of claim terminology possibly having multiple interpretations.13 The term "self-similar" was used in the patent claims at issue in Clearone to describe an arrangement of microphone transducers.
The defendant argued that the claims were indefinite because there are varying interpretations of the self-similar term. But the Federal Circuit rejected this argument and noted that "[j]ust because a term is susceptible to more than one meaning does not render it indefinite" because "[s]uch a test would render nearly every claim term indefinite so long as a party could manufacture a plausible construction."14
As in other cases where the court found claims to be not indefinite, the Federal Circuit found that the patent's specification established reasonable certainty as to the scope of the term. In this case, the court was persuaded by particular examples in the specification of microphone transducers arrange in a self-similar manner.
The necessity of performing a measurement to evaluate claim terminology is another issue that can lead to claim terms being found indefinite. Such an issue arises from the potential variability in measurement techniques, conditions, and interpretations, which can lead to uncertainty as to the scope of the claims. However, the Federal Circuit has recognized that the necessity of a measurement in relation to a claim term is not inherently fatal under the Nautilus reasonable certainty test.
Presidio Components, Inc. v. American Tech. Ceramics Corp. demonstrates the Federal Circuit's willingness to allow for claim terminology that requires measurements.15 The claims in the asserted patent recited fringe-effect capacitance in a capacitor, which required measurement in terms of a standard unit.
The court noted that under its "post-Nautilus cases, a claim is not indefinite if a person skilled in the art would know how to utilize a standard measurement method ... to make the necessary measurement."16 Looking to the specification of the patent, the court found a description of a method of measuring performance of capacitors (as in the claim), which was referred to as insertion loss testing.
The court also found references to the insertion lost testing method in the prosecution history before the USPTO, and that the testing method was well-known in the relevant art. Thus, the court concluded that the guidance provided by the intrinsic evidence was sufficient to render the scope of the claims reasonably certain.
The case Ethicon Endo-Surgery, Inc. v. Covidien, Inc. provides another example of claim terminology requiring measurement but not being indefinite.17 The claims in this case covered surgical sheers for cutting and sealing blood vessels that required a clamping pressure to be within a specified range.
Even though there was no industry standard method for measuring clamping pressure, the court found that the patent's specification provided guidance as to how to make such a measurement.
The court therefore found the case to be different from other cases where there was no guidance as to how to measure a critical element of the claims in the patent specification or known in the art. Thus, the court concluded that one of ordinary skill in the art know how to determine clamping pressure as in the claim, and the claim scope was reasonably certain as required by Nautilus.
The Federal Circuit's applications of the reasonable certainty test suggest that the standard is not as significantly restrictive as may have been thought immediately following Nautilus.
In finding claim terms involving terms of degree, the possibility of multiple interpretations of claim terminology, or measurements to be definite under the reasonable certainty standard, the court's cases indicate there is still significant leeway for claim language. If the intrinsic evidence of the patent provides guidance, then a court may find the patent's claim terminology to be reasonably certain and not indefinite.
Footnotes
2. Id. at 891.
3. Teva Pharms. USA Inc. v. Sandoz Inc., 789 F.3d 1335, 1349 (Fed. Cir. 2015).
5. Niazi Licensing Corp. v. St. Jude Med. S.C. Inc., 30 F.4th 1339, 1347 (Fed. Cir. 2022).
6. 879 F.3d 1332 (Fed. Cir. 2018).
8. Id.
9. 936 F.3d 1353 (Fed. Cir. 2019).
10. Id. at 1360.
11. See, e.g., Liberty Ammunition, Inc. v. U.S., 835 F.3d 1388, 1396 (Fed. Cir. 2016).
12. Nautilus, 572 U.S. at 911, n. 8. (citing Every Penny Counts Inc. v. Wells Fargo Bank NA, 4 F.Supp.3d 1286 (M.D. Fla. 2014)).
13. 35 F.4th 1345 (Fed. Cir. 2022).
14. Id. at 1351 (citing Nevro Corp. v. Bos. Sci. Corp., 955 F.3d 35 (Fed. Cir. 2020)).
15. 875 F.3d 1369 (Fed. Cir. 2017).
16. Id. at 1376.
17. 875 F.3d 1376.
Originally published by Westlaw Today.
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