Fortress Iron, Lp v. Digger Specialties, Inc.

United States Court of Appeals
for the Federal Circuit
______________________
FORTRESS IRON, LP,
Plaintiff-Appellant
v.
DIGGER SPECIALTIES, INC.,
Defendant-Appellee
______________________
2024-2313
______________________
Appeal from the United States District Court for the
Northern District of Indiana in No. 3:21-cv-00014-CCB,
Judge Cristal C. Brisco.
______________________
Decided: April 2, 2026
______________________
P AUL V. STORM , Foley & Lardner LLP, Dallas, TX, ar-
gued for plaintiff-appellant. Also represented by J OHN
J ACOB MAY .
HEATHER B. REPICKY , Barnes & Thornburg LLP, Bos-
ton, MA, argued for defendant-appellee. Also represented
by D. RANDALL BROWN, Fort Wayne, IN; D ANA AMATO
SARROS , Chicago, IL.
______________________
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FORTRESS IRON, LP v. DIGGER SPECIALTIES, INC. 2
Before L OURIE and H UGHES , Circuit Judges, and K LEEH ,1
Chief District Judge.
L OURIE, Circuit Judge.
Fortress Iron, LP (“Fortress”) appeals from a decision
of the United States District Court for the Northern
District of Indiana. Fortress Iron L.P. v. Digger Specialties,
Inc., 748 F. Supp. 3d 614, 621 (N.D. Ind. 2024) (“Decision”).
The district court granted summary judgment, holding
that U.S. Patents 9,790,707 (“the ’707 patent”) and
10,883,290 (“the ’290 patent”) were invalid because they
omitted a coinventor. Id. The district court also denied
partial summary judgment to correct inventorship under
35 U.S.C. § 256(b). Id. For the reasons given below, we
affirm.
BACKGROUND
I
Fortress designs and sells railing and fencing products
used in the construction of outdoor living spaces. Id.
at 616; Open. Br. at 6. Fortress works with two Chinese
companies to manufacture their products: manufacturer
Yinxin Handicrafts Co., Ltd. (“YX”) and quality control
liaison Quan Zhou Yoddex Building Material Co., Ltd.
(“YD”). Decision, 748 F. Supp. 3d at 616.
In March 2013, Fortress’s owner, Matthew Sherstad,
“had an idea for a vertical cable railing that could be
purchased as a pre-assembled panel.” Id. The pre-
assembled aspect made it easier to install compared to
products that needed to be assembled on site. See id.
Fortress employee Kevin Burt sketched an initial design of
the product. Id. Sherstad and Burt worked with YD to
1 Honorable Thomas S. Kleeh, Chief United States
District Judge, United States District Court for the North-
ern District of West Virginia, sitting by designation.
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FORTRESS IRON, LP v. DIGGER SPECIALTIES, INC. 3
produce a prototype, but it had problems with the cables
rotating during tensioning. See id. YD employees Hua-
Ping Huang and Alfonso Lin then suggested changes to
address the cable tensioning issue. Id. at 617. Those
suggested changes were incorporated into the final design.
Id. The final design thus incorporated aspects of
Sherstad’s original idea, Burt’s early designs, and the
suggestions of Lin and Huang as to the final cable and rail
designs. Id.
Soon after the final design was completed, Fortress
filed patent applications for the vertical cable railing
panels, which issued as the ’707 and ’290 patents. Id.
Initially, the patents named only Sherstad and Burt as
inventors; they did not include Lin or Huang. Id. As
relevant to this appeal, Huang’s employment at YD ended
in 2016, and he did not provide his contact information to
YD or Fortress. Id. at 618.
II
In January 2021, Fortress sued Digger Specialties Inc.
(“DSI”) for infringement of the ’707 and ’290 patents. See
id. at 615; J.A. at 13.2 During the course of the litigation,
DSI learned that Lin and Huang contributed to the
invention, and Fortress acknowledged that Lin and Huang
were coinventors. Decision, 748 F. Supp. at 618. Fortress
located Lin and successfully added him as a coinventor to
the patents following the procedure outlined in 35 U.S.C.
§ 256(a). See id.; J.A. at 330–32, 337–39. But because
Huang did not provide his contact information, Fortress
was unable to locate him and thus was unable to add him
as a coinventor using that same procedure. See Decision,
748 F. Supp. at 618.
The parties then filed cross motions for summary
judgment. Id. at 616. Fortress moved for partial summary
2 J.A. refers to the Joint Appendix filed at ECF 18.
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FORTRESS IRON, LP v. DIGGER SPECIALTIES, INC. 4
judgment to correct the ’707 and ’290 patents by adding
Huang as a coinventor pursuant to 35 U.S.C. § 256(b). Id.;
J.A. at 110–11. DSI opposed Fortress’s motion and moved
for summary judgment of invalidity due to incorrect
inventorship. Decision, 748 F. Supp. 3d at 616. The
district court denied Fortress’s motion to the extent that it
did not order correction of the ’707 and ’290 patents, then
granted DSI’s motion, holding that the patents were
invalid for omission of an inventor. Id. at 621.
Fortress appeals, and we have jurisdiction under
28 U.S.C. § 1295(a)(1).
S TANDARD OF REVIEW
We review a district court’s ruling of summary
judgment under the law of the regional circuit—here, the
Seventh Circuit. See Cummins, Inc. v. TAS Distrib. Co.,
700 F.3d 1329, 1334–35 (Fed. Cir. 2012). “The Seventh
Circuit reviews a district court’s grant of summary
judgment de novo.” Id. at 1335 (citing Staats v. Cnty. of
Sawyer, 220 F.3d 511, 514 (7th Cir. 2000)). “Summary
judgment will be affirmed only if [the movant] is entitled
to prevail as a matter of law on the basis of the stipulated
facts.” Broad. Music, Inc. v. Claire’s Boutiques, Inc.,
949 F.2d 1482, 1486 (7th Cir. 1991). We must draw any
necessary fact inferences in favor of the nonmovant. Id.
D ISCUSSION
Fortress argues that the district court erred in
(1) denying its partial summary judgment motion to
correct inventorship under 35 U.S.C. § 256(b); and
(2) granting DSI’s motion for summary judgment of
invalidity due to incorrect inventorship. See Open. Br.
at 16–17. Before we address each argument in turn, we
provide a short background on inventorship and 35 U.S.C.
§ 256.
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FORTRESS IRON, LP v. DIGGER SPECIALTIES, INC. 5
I
A patent must accurately name those who invented its
claimed subject matter. See 35 U.S.C. §§ 115(a), 116(a);
Pannu v. Iolab Corp., 155 F.3d 1344, 1348–49 (Fed. Cir.
1998); cf. Thaler v. Vidal, 43 F.4th 1207, 1211 (Fed. Cir.
2022) (“The Patent Act also requires inventors . . . to
submit an oath or declaration [with a patent application].”
(citing 35 U.S.C. § 115(b)(2))). Failure to do so renders a
patent invalid. See Pannu, 155 F.3d at 1349 (“[N]onjoinder
of an actual inventor . . . render[s] a patent invalid.”)
(collecting cases).
Congress, however, affords a patentee who incorrectly
listed inventors the opportunity to correct its patent by
complying with the requirements of 35 U.S.C. § 256. Id. at
1350. Section 256 provides:
(a) Correction.––Whenever through error a person
is named in an issued patent as the inventor, or
through error an inventor is not named in an is-
sued patent, the Director may, on application of all
the parties and assignees, with proof of the facts
and such other requirements as may be imposed,
issue a certificate correcting such error.
(b) Patent Valid if Error Corrected.––The error of
omitting inventors or naming persons who are not
inventors shall not invalidate the patent in which
such error occurred if it can be corrected as pro-
vided in this section. The court before which such
matter is called in question may order correction of
the patent on notice and hearing of all parties con-
cerned and the Director shall issue a certificate ac-
cordingly.
We have described § 256 as a “savings provision” such
that “[i]f a patentee demonstrates that inventorship can be
corrected as provided for in [§] 256, a district court must
order correction of the patent, thus saving it from being
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FORTRESS IRON, LP v. DIGGER SPECIALTIES, INC. 6
rendered invalid.” Pannu, 155 F.3d at 1350. Section
256(b), however, does not automatically allow a court to
order correction of a patent. Rather, the court may only do
so “on notice and hearing of all parties concerned.”
35 U.S.C. § 256(b).
With this background in mind, we turn to the instant
appeal and case of first impression,3 which turns on
whether Huang––an agreed-upon omitted coinventor––is a
“party concerned” under § 256(b).
II
We first address Fortress’s argument that the district
court erred in denying its partial summary judgment
motion to correct inventorship under 35 U.S.C. § 256(b).4
Specifically, Fortress contends that the district court erred
in concluding that Huang was a “party concerned” under
§ 256(b) and therefore entitled to notice and an opportunity
to be heard before the court could order any correction of
inventorship. See Open. Br. at 25–31; Decision, 748 F.
Supp. 3d at 619–20.
We disagree. Inventors occupy the central role in the
patent process. They are where it all begins, even if they
eventually assign their interests to others, such as
3 See Oral Arg. at 2:56–3:06, available at
cafc.uscourts.gov/oral-arguments/24-2313_02062026.mp3
(Fortress’s counsel agreeing this is a “case of first impres-
sion”); id. at 15:30–50 (DSI’s counsel agreeing “there is no
case on point” for these facts).
4 Before the district court, Fortress conceded it could
not utilize the process under 35 U.S.C. § 256(a) to add
Huang as an inventor to the patents. Decision, 748 F.
Supp. 3d at 619. We express no view on the basis for that
concession, and Fortress does not contend it can satisfy
§ 256(a) now. See Open. Br. at 3.
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FORTRESS IRON, LP v. DIGGER SPECIALTIES, INC. 7
employers. Thus, their explicit references in the statutory
framework cannot be taken lightly.
In Chou v. University of Chicago, where the question
arose of an inventor’s right to participate in a § 256(b)
action even when she had no ownership rights in the patent
at issue, we determined that a coinventor was a “party
‘concerned,’ . . . clearly within the purview of [§ 256(b)].”
254 F.3d 1347, 1357 (Fed. Cir. 2001). Huang, similarly, as
an agreed-upon omitted coinventor, is thus a “party
concerned” such that he must be given notice and
opportunity for hearing prior to any correction of
inventorship under § 256(b). See id.
Fortress concedes that it has been unable to contact
Huang, let alone provide him with notice and an
opportunity to be heard as required by the statute. See
Decision, 748 F. Supp. 3d at 619–20; Open. Br. at 12 n.2.
It argues that that inability to provide those protections
should not deprive it of a valid patent. See Open. Br.
at 25–30. But § 256(b) makes those procedural protections
a prerequisite to relief, not a mere formality; because
Fortress cannot satisfy the notice and hearing prerequisite
of § 256(b), it cannot utilize that section to correct the
patents.
Fortress’s counterarguments are unpersuasive.
Fortress first asks us to read a “party concerned” under
§ 256(b) through a “due process” lens, i.e., a “party
concerned” is one with an economic interest in the patent
that may be adversely affected. Open. Br. at 25–28; see
Oral Arg. at 6:04–6:10, 7:17–22. Fortress asserts that
Huang is not a “party concerned” because adding him as a
coinventor would benefit him, not adversely affect him.
Open. Br. at 27. But Fortress’s characterization of Huang’s
position is unsupported. Neither the parties, nor we, know
for certain whether Huang would be adversely affected or
would benefit by being listed as an inventor on the patent.
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And more importantly, to conflate a “party concerned”
with those with potentially adversely affected property
interests would be to rewrite the language of the statute
from “party concerned” to “those with an economic interest
that may be adversely affected”. That is something we
cannot do. See Newport News Shipbuilding & Dry Dock
Co. v. Garrett, 6 F.3d 1547, 1558 (Fed. Cir. 1993) (“This
court is empowered to rewrite neither statutes nor
regulations.”) While the statute does not define a “party
concerned,” it does not follow that a coinventor of a patent
is not a “party concerned” when it comes to adding or
removing a coinventor. Inventorship carries legal,
financial, and ownership consequences that an inventor
has a right to contest. See 35 U.S.C. § 262 (“In the absence
of any agreement to the contrary, each of the joint owners
of a patent may make, use, offer to sell, or sell the patented
invention within the United States, or import the patented
invention into the United States, without the consent of
and without accounting to the other owners.”); Ethicon,
Inc. v. U.S. Surgical Corp., 135 F.3d 1456, 1465 (Fed. Cir.
1998) (“each [coinventor] presumptively owns a pro rata
undivided interest in the entire patent”).
Fortress next argues that Huang is not a “party
concerned” because he would not have constitutional
standing if he sought to name himself a coinventor. Open.
Br. at 28–30. That argument fares no better. In Chou, we
explained that constitutional standing and “party
concerned” status under § 256(b) are distinct issues with
different requirements. See 254 F.3d at 1357 (“Chou, as a
party ‘concerned,’ is clearly within the purview of
[§ 256(b)], but she must meet constitutional standing
requirements in order to invoke it.”). Fortress thus again
asks us to improperly conflate “party concerned” with a
different requirement; we again decline. See Newport
News, 6 F.3d at 1558.
Finally, Fortress argues that the district court erred by
“restrictively constru[ing] § 256(b) to avoid saving the
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FORTRESS IRON, LP v. DIGGER SPECIALTIES, INC. 9
validity of the patents-in-suit,” as district courts are to
apply the subsection “broadly and permissively” due to its
“savings provision” status. Open. Br. at 20–21. While
Fortress is correct that § 256 has been characterized as a
“savings provision,” Pannu, 155 F.3d at 1350, we disagree
with its argument. Section 256 is a “savings provision”
only to the extent that its statutory requirements are met.
The statute reads, “can be corrected as provided in this
section.” 35 U.S.C. § 256(b). As previously stated, because
Fortress cannot satisfy the notice and hearing prerequisite
of this section, this “savings provision” does not apply.
Accordingly, we affirm the district court’s denial of
Fortress’s partial motion for summary judgment for
inventorship correction under § 256(b).
III
Next, we address Fortress’s argument that the district
court improperly granted summary judgment of invalidity
due to incorrect inventorship. The district court, based on
§ 101, held that because Huang was not named on the
patents, they were invalid. Decision, 748 F. Supp. 3d at
620–21.
The district court was correct in its invalidity
conclusion. Invalidity for incorrect listing of inventors has
a clear basis in the statute. Section 256(b) states that
“[t]he error of omitting inventors or naming persons who
are not inventors shall not invalidate the patent in which
such error occurred if it can be corrected.” (emphasis
added). The necessary and opposite implication of § 256(b)
is that a patent is invalid for the error of omitting inventors
when that error cannot be corrected.
Fortress argues that only one true inventor need be
identified on the patents. Reply Br. at 23. But adopting
Fortress’s position when a patent cannot be corrected
under § 256 would render meaningless the “savings
provision” that Fortress sought to rely on at summary
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FORTRESS IRON, LP v. DIGGER SPECIALTIES, INC. 10
judgment. Section 256(b) saves patents from invalidity for
the “error of omitting inventors.” Fortress’s position would
mean that omission of an inventor, as long as one inventor
is named, would not be an error at all. But “we must ‘give
effect, if possible, to every clause and word of a statute’ and
should avoid rendering any of the statutory text
meaningless or as mere surplusage.” Sharp v. United
States, 580 F.3d 1234, 1238 (Fed. Cir. 2009) (quoting
Duncan v. Walker, 533 U.S. 167, 174 (2001)). Because
Fortress’s position that only one inventor need be listed
would render the statutory text meaningless, we decline to
adopt it. See id.
Furthermore, and as stated above, our caselaw shows
a historical basis for requiring a correct listing of inventors
and that “nonjoinder of an actual inventor would render a
patent invalid.” See Pannu, 155 F.3d at 1349 (collecting
cases).
Fortress’s arguments to the contrary are unavailing.
Fortress contends that because 35 U.S.C. § 101 uses
permissive language—“[w]hoever invents . . . may obtain a
patent thereof”—only one inventor need be listed. See
Open. Br. at 44. We disagree. In the context of joint
invention, “[t]he term ‘inventor’ means . . . the individuals
collectively who invented or discovered the subject matter
of the invention.” 35 U.S.C. § 100(f) (emphasis added).
Thus, § 101 and § 100(f), when read together with § 256(b),
contemplate that when an invention has multiple
inventors, they must all be listed on the patent. “Whoever”
does not mean less than all.
Fortress next argues that the repeal of section 102(f)
supports its view that joinder of all inventors is not
necessary for validity. See Open. Br. at 44. We again
disagree. Section 102(f), repealed after the enactment of
the America Invents Act, stated that “[a] person shall be
entitled to a patent unless he did not himself invent the
subject matter sought to be patented.” But that provision
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simply stated that non-inventors are not entitled to a
patent, not that actual inventors need not be named on a
patent. Courts have long held, even prior to the enactment
of § 102(f), that nonjoinder of an inventor invalidates a
patent. See Pannu, 155 F.3d at 1349 (collecting cases). The
relevant legislative history further illuminates that
“[§ 102(f)] merely emphasize[d] that it is the inventor that
applies for the patent.” Id. (quoting S. Rep. No. 82-1979,
at 5 (1952) (Conf. Rep.), reprinted in 1952 U.S.C.C.A.N.
2394, 2395). Thus, the repeal of § 102(f) did not eliminate
invalidity due to incorrect listing of inventors.
Accordingly, we hold that a patent which incorrectly
lists its inventor(s) and cannot be corrected according to
law is invalid. Because it is undisputed that Huang is a
coinventor, see Decision, 748 F. Supp. 3d at 619, the
patents suffer from the error of an omitted inventor. And
because Fortress could not correct the patents under § 256,
the patents are therefore invalid due to an omitted
inventor. We thus affirm the district court’s grant of DSI’s
motion for summary judgment of invalidity.
CONCLUSION
We have considered the remainder of Fortress’s
arguments but find them unpersuasive. For the foregoing
reasons, we affirm the summary judgment decision of the
district court.
AFFIRMED
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