Claim Construction and Due Process: Examining NST Global v. Sig Sauer Inc. in the Supreme Court

by Dennis Crouch

NST Global, LLC, dba SB Tactical v. Sig Sauer Inc. (Supreme Court 2023)

This case has a low chance of being granted certiorari, but it still has some interesting elements regarding claim construction and procedure.  This is a perfect case for the Supreme Court to issue a GVR (Grant-Vacate-Remand) with an order to the Federal Circuit to explain its reasoning.

The setup is common. Tactical sued Sig Sauer for patent infringement; Sig Sauer responded with an IPR petition that was eventually successful.  Tactical appealed based upon the PTAB’s sua sponte claim construction that found the preamble to be limiting, but the Federal Circuit Affirmed without opinion.

The Supreme Court petition asks three questions:

  1. Whether the claim construction finding the preamble limiting was improper.
  2. Whether the PTAB violated due process by construing the term sua sponte and failing to give the patentee with notice or an opportunity to present evidence.
  3. Whether the Federal Circuit’s use of Rule 36 violates constitutional guarantees  of due process and the statutory protections of 35 U.S.C. 144.

The Tactical patents cover a forearm stabilizing brace that can be attached to a pistol. U.S. Patent Numbers 8,869,444 and 9,354,021. Sig Sauer initially was a distributor of Tactical’s product, but later began making its own competing product. At that point Tactical sued.

In the IPR petition, Sig Sauer did not request any claim construction. Likewise, the petition decision granting the IPR stated that no claim terms needed any express construction.  “We agree—we need not expressly construe any claim term
to resolve the parties’ dispute.”  During briefing, neither party requested construction of any aspect of the claim preambles.  Eventually though, in its final written decision, the PTAB interpreted the preambles as limiting and then used that construction to conclude that the claims were invalid as obvious.

Yes, I said that the narrow construction led to the claims being found invalid.  That is unusual — usually the addition of limitations helps to avoid the prior art. In this case though the focus was on objective indicia of non-obviousness. NST’s sales; copying by Sig; praise; etc.  But, by giving weight to the preamble terms, the PTAB was able to destroy the presumed nexus between the claims and NST’s product.  The result, those secondary indicia were found wanting because NST had not provided additional evidence “commensurate with the claims” as newly construed.

For context, the claims are directed to the attachment, but the preamble recites “a handgun” and “a support structure extending rearwardly from the rear of the handgun:”

1. A forearm-gripping stabilizing attachment for a handgun, the handgun having a support structure extending rearwardly from the rear end of the handgun, the forearm-gripping stabilizing attachment, comprising: . . .

The PTAB ruled that the claims require the handgun and also the support structure  as recited in the preamble along with the forearm attachment described in the body.  The problem for the patentee is that its objective indicia evidence focused on the forearm attachment, not the whole package.  Thus, no nexus and no weight given to those secondary factors.  In its decision, the PTAB when through the whole life and meaning analysis: “we conclude that the preambles of claims 1, 3, and 5 are ‘necessary to give life, meaning, and vitality to the claim[s],’ and, as such, are limiting.”

The case was already close because there is a long history of this sort of stabilizer going back to the 19th Century, and so the absence of secondary considerations led to the obviousness conclusion.

During the IPR trial, Sig Sauer had argued that the high sales were due to an odd regulatory scheme against semi-automatic rifles, and the pistol attachment was actually popular primarily because it allowed the pistol to be shouldered.  On appeal, that was raised as an alternative justification for the judgment. But, in my view, the PTAB did not actually rule on that issue in the first place.

The patentee appealed, but the Federal Circuit panel of Judges Reyna, Schall, and Chen affirmed without opinion.

25 thoughts on “Claim Construction and Due Process: Examining NST Global v. Sig Sauer Inc. in the Supreme Court

  1. 7

    Not a great outcome given the sua sponte construction without giving Tactical notice or the opportunity to present evidence or arguments. This needs to be addressed and put to rest as terrible precedent.

    On the other hand, with regards to the potentially limiting effect of preambles, the CAFC has been *cough* clear for decades – these may…or may not be limiting. The prudent practitioner would do well to keep their preambles to a minimum and not include terms that could be construed as limitations.

    1. 7.1

      Prudent practitioners recognize the court-induced uncertainty and may well PLAN on leveraging that tactically.

  2. 6

    Yet another patent first brought into court litigation but then killed in the Patent Office. Should that set of events be considered the norm, going forward? That is, if my client wants to assert its patent either by letter or in court, should the client be warned that its patent will most likely be attacked in the PTAB before ever getting to a judge or jury or settlement talks? Be warned that the issue of patentability will be at the fore, not the issue of infringement? If so, that is an upending of the way it was done for ages. As I recall, there is a presumption of validity in court proceedings, but is that still the case in the PTO?

      1. 6.1.1

        (e) EVIDENTIARY STANDARDS.—In an inter partes review instituted under this chapter, the petitioner shall have the burden of proving a proposition of unpatentability by a preponderance of the evidence.

        Not clear and convincing evidence.


          Certainly – I have always made it a point that the IPR scheme engaged in a legislative takings of one of the sticks in the bundle of patent rights (See i4i) in that a mere decision to institute (prior to any judgement on the merits) REMOVES the clear and convincing standard accorded a granted patent.

          You have made my point here – should I say Thank You?

  3. 5

    Dennis, yesterday or the day before you posted on Twitter that this blog (if I recall correctly) contains a new blog about something like “When is the right time to file your patent application?” Did you change your mind about posting it, or did I misunderstand your Twitter post?
    Robert Buckley

  4. 4

    I’m skeptical of the conclusion. It sounds more-likely that the patentee needed antecedent basis for some terms… so introduced them in the preamble (vs. an actual claim element) precisely to avoid them being limiting.

    That said, I’m also not sure I get the nexus issue here. Was anyone (including the ‘praisers’) using the attachment separate from a firearm e.g., with gardening tools??

  5. 3

    “with an order to the Federal Circuit to explain its reasoning.”

    Explain?! Explain our reasoning!?

    What’s next . . . take away our beloved, no-justice Rule 36?!

    Say it ain’t so, Joe! Say it ain’t so!

  6. 2

    Is determining whether a preamble is limiting actually “claim construction”? This determination sometimes happens during claim construction in order to determine whether preamble terms themselves need to be construed. But that’s not quite the same as it being a matter of claim construction.

    The petition cites to an unpublished 2004 case in the F. App’x that doesn’t even say it explicitly, and there is no other support for the idea that determining whether a preamble is limiting counts as claim construction (therefore necessitating a markman hearing)…

    1. 2.1

      Is it not a flavor of “construing” to — in fact — determine if the terms are limiting?

      You indicate not quite the same, but how is essence is this NOT quite the same?

      (no snark)

    2. 2.2

      > Is determining whether a preamble is limiting actually
      > “claim construction”?

      See, for example, SIMO Holdings Inc. v. Hong Kong uCloudlink Network Technology Limited. 983 F.3d 1367, 1374 (Fed. Cir. 2021) (“Whether preamble language is limiting is a claim-construction issue.”). And besides, why wouldn’t it be?

      1. 2.2.1

        Thanks LR – I was hoping that Ocho could explicate ’their’ position. My reply really was snark-free.


            Nope – no results found.

            Not altogether unsurprising though – that forum has a horrendous dialogue protocol.


              Janice M. Mueller teaches at the Chisum Patent Academy. Link with her and it is one of her posts. I think she edits now the Chisum on Patent treatise.

    1. 1.2

      Thanks, NW.

      That moderator sounds much more incoherent than Judge Newman. Maybe just picking his words carefully.

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