Federal Circuit: Indefiniteness Is Not Judged by the 'Claim Language, Standing Alone'

Feb 22, 2022

Reading Time : 2 min

In Nature Simulations Systems, Inc. v. Autodesk, Inc., the patent owner asserted two patents related to methods for building 3-D models. The district court held both patents invalid, finding that multiple claim terms raised “unanswered questions” that render the claims indefinite. The district court further rejected the patent owner’s argument that the specification answers those questions. According to the district court, any questions must be answered by the language of the claims themselves, and a failure to do so renders the claims indefinite as a matter of law.

In a 2-1 decision, the Federal Circuit reversed, holding that the district court’s “unanswered questions” analysis was improper. “Claim language, standing alone” is not the correct legal standard. Patent claims must be read and understood in light of the specification, the prosecution history, and other relevant evidence bearing on how a skilled artisan would understand the scope of the invention. Thus, the district court erred by narrowly focusing only on the claim language and by refusing to consider either the patent specification or the prosecution history.

Having clarified the appropriate legal standard, the majority then reviewed the specification and prosecution history and found the patent claims not indefinite. It identified portions of the patent specification describing the claimed method and noted that it was “not disputed that the specification describes and enables practice of the claimed method.” The majority further noted that the claim language in question was added by the Examiner during prosecution, not the patentee. In light of this fact, the majority deferred to the Examiner’s choice of claim language, quoting an earlier Federal Circuit decision reasoning that “[w]e presume that an examiner would not introduce an indefinite term into a claim when he/she chooses to amend the claim for the very purpose of putting the application in a condition for allowance.” 

Judge Dyk dissented, arguing that the majority gave too much deference to the claim language added by the Examiner. According to Judge Dyk, the claim language included limitations that were not described or defined in the patent specification. And the only evidence about the meaning of the terms came from the defendant’s expert, who testified without contradiction that the additional limitations are “ambiguous,” “unclear,” and inconsistent with the patents’ figures. 

Practice Tips: In any dispute over whether patent claim terms are sufficiently definite, both sides should take care to account for the prosecution history and the patent specification. Moreover, where the challenged claim language was added by the Examiner during prosecution, the accused infringer should give detailed reasons why the court should not defer to the Examiner’s choice of claim language.

Nature Simulation Sys., Inc. v. Autodesk, Inc., 2020-2257 (Fed. Cir. Jan. 27, 2022).

Share This Insight

Previous Entries

IP Newsflash

August 11, 2025

In considering a motion to dismiss infringement claims for two related patents, the District of Massachusetts recently held that pre-suit knowledge of a “parent” patent, without more, is insufficient to establish pre-suit knowledge of the “child” patent for purposes of indirect and willful infringement.

...

Read More

IP Newsflash

August 8, 2025

Following a jury verdict finding trade secret misappropriation, the District Court for the District of Massachusetts granted-in-part a plaintiff’s motion for a permanent injunction to prohibit defendants from using plaintiff’s trade secrets. The district court further required defendants to reassign to plaintiff patents and patent applications that disclosed or were derived from plaintiff’s trade secrets as part of its equitable relief.

...

Read More

IP Newsflash

August 6, 2025

In ruling on a recent motion to strike, a judge in the Eastern District of Texas permitted a damages expert to rely on a damages theory based on defendant’s “avoided costs,” holding that this theory did not run afoul of the “entire market value rule.”

...

Read More

IP Newsflash

August 5, 2025

The Federal Circuit recently vacated a decision by the Patent Trial and Appeal Board after concluding that the board’s analysis of licensing evidence offered as a secondary consideration of nonobviousness constituted legal error and was not supported by substantial evidence. According to the court, the board applied a more exacting and improperly heightened nexus standard than is required by law for license evidence.

...

Read More

IP Newsflash

August 5, 2025

A Northern District of California judge recently granted a motion to reconsider his summary judgment ruling that defendant was barred from raising certain “device art” due to IPR estoppel under 35 U.S.C. § 315(e)(2). In the original ruling, the judge adopted the broader rule that IPR estoppel applies to device art that is “materially identical” to patents or printed publications that petitioners raised, or could have raised, in an IPR. Following that ruling, however, the Federal Circuit issued its Ingenico decision adopting the narrower view that IPR estoppel applies only to “grounds” based on patents and printed publications and not to device-based grounds. Citing Ingenico as a “change of law,” defendant moved for reconsideration of the court’s ruling, and the court granted the motion.

...

Read More

IP Newsflash

August 5, 2025

In a recent decision designated as Informative, the USPTO Director determined that the Patent Trial and Appeal Board abused its discretion by instituting two inter partes review proceedings challenging the same patent, based on petitions advancing different constructions of the same claim term. The Director expressed concerns that permitting multiple petitions based on alternative claim constructions effectively circumvents word count limitations, strains board resources, and undermines procedural efficiency.

...

Read More

IP Newsflash

July 25, 2025

Earlier this year, the Federal Circuit’s decision in Qualcomm Inc. v. Apple Inc. (Qualcomm II) raised questions about the extent to which petitioners can rely on applicant admitted prior art (“AAPA”) in inter partes review proceedings.  The Federal Circuit’s recent decision in Shockwave Medical, Inc. v. Cardiovascular Sys., Inc. largely cabins the Qualcomm II decision to its particular facts and makes clear that AAPA can be used as evidence of background knowledge as part of an obviousness argument.

...

Read More

IP Newsflash

July 11, 2025

The Federal Circuit recently reversed a PTAB determination on remand that a patent was obvious over applicant admitted prior art (“AAPA”) in combination with prior art patents, holding that expressly designating AAPA as a “basis” for a ground is improper under 35 U.S.C. § 311(b). In doing so, the Court rejected the PTAB’s “blanket rule” that “AAPA used in combination with prior art patents or printed publications under § 311(b) is ipso facto not the basis or part of the basis of a ground.” Ultimately, while the case clarifies that expressly listing AAPA in an IPR ground is improper, the precise line between proper and improper uses of AAPA in other instances remains unclear.

...

Read More

© 2025 Akin Gump Strauss Hauer & Feld LLP. All rights reserved. Attorney advertising. This document is distributed for informational use only; it does not constitute legal advice and should not be used as such. Prior results do not guarantee a similar outcome. Akin is the practicing name of Akin Gump LLP, a New York limited liability partnership authorized and regulated by the Solicitors Regulation Authority under number 267321. A list of the partners is available for inspection at Eighth Floor, Ten Bishops Square, London E1 6EG. For more information about Akin Gump LLP, Akin Gump Strauss Hauer & Feld LLP and other associated entities under which the Akin Gump network operates worldwide, please see our Legal Notices page.