       NOTE: This disposition is nonprecedential.


  United States Court of Appeals
      for the Federal Circuit
                ______________________

 UNILOC USA, INC., UNILOC LUXEMBOURG S.A.,
              Plaintiffs-Appellants

                           v.

                    APPLE INC.,
                  Defendant-Appellee
                ______________________

                      2018-2094
                ______________________

   Appeal from the United States District Court for the
Northern District of California in No. 3:18-cv-00358-WHA,
Judge William H. Alsup.
                 ______________________

               Decided: August 30, 2019
                ______________________

   JAMES J. FOSTER, Prince Lobel Tye LLP, Boston, MA,
argued for plaintiffs-appellants. Also represented by
AARON JACOBS, PAUL J. HAYES, I.

    MICHAEL T. PIEJA, Goldman Ismail Tomaselli Brennan
& Baum, LLP, Chicago, IL, argued for defendant-appellee.
Also represented by LAUREN ABENDSHIEN, JENNIFER
GREENBLATT, ALAN ERNST LITTMANN, ANDREW RIMA, EMMA
ROSS, DOUG J. WINNARD.
                ______________________
2                                UNILOC USA, INC. v. APPLE INC.




 Before PROST, Chief Judge, PLAGER and HUGHES, Circuit
                        Judges.
HUGHES, Circuit Judge
     Uniloc USA, Inc. and Uniloc Luxembourg S.A. appeal
a final judgment on the pleadings in the United States Dis-
trict Court for the Northern District of California holding
the claims of U.S. Patent No. 6,661,203 ineligible. Uniloc
USA, Inc. v. Apple Inc., No. C 18-00358 WHA, 2018 WL
2287675, at *1 (N.D. Cal. May 18, 2018). After Uniloc filed
the appeal, Apple, Inc., uncovered material suggesting
multiple jurisdictional defects. Because this material is
outside the record, we remand for the district court to sup-
plement the record, determine whether Uniloc has stand-
ing in the first instance, and, if appropriate, cure any
jurisdictional defects.
                             I
                            A.
    This case began when Uniloc sued Apple for infringe-
ment of the ’203 patent. It is one of several ongoing patent
infringement cases between the Uniloc entities and Apple
in the Northern District of California. 1 During discovery
in a related proceeding, Apple requested information about
the ownership and licensing of Uniloc’s patents. Uniloc did
not comply with those requests.
    According to Apple, on May 3, 2018, Uniloc Luxem-
bourg, the entity that owned the ’203 patent, transferred
its patent holdings to Uniloc 2017 LLC (May 3 transfer).
It failed to inform Apple or the district court about this
transfer. Uniloc 2017 then entered into a licensing agree-
ment with Uniloc USA that gave Uniloc USA authority to


    1   Uniloc USA, Inc., v. Apple Inc., 3:18-cv-360, 3:18-
cv-363, 3:18-cv-365, 3:18-cv-572 (N.D. Cal.).
UNILOC USA, INC. v. APPLE INC.                            3



enforce the patents. Under the licensing agreement,
Uniloc USA would remit all enforcement proceeds to Uniloc
2017.
    On May 18, 2018, the district court granted Apple’s mo-
tion for judgment on the pleadings after finding the claims
of the ’203 patent were directed to non-patentable subject
matter. Uniloc appealed.
                                 B.
    Apple did not learn about the May 3 transfer until late
August 2018, after the district court entered judgment in
this case. But, because the related cases were still before
the district court, Apple asked Uniloc to produce any docu-
ments regarding the transfer of ownership in those cases.
Uniloc did not respond to Apple’s request, so the district
court ordered Uniloc to “provide the Court and [Apple] with
a detailed account setting forth the exact history of owner-
ship of the patents-in-suit by Uniloc Luxembourg, S.A. and
Uniloc USA, Inc. and the exact history of any ownership
interest by Uniloc 2017, LLC” along with “complete details
about ownership (including licensing) of the patents-in-
suit.” Apple’s Opp’n to Pl.-Appellant’s Mot. to Substitute
Uniloc 2017 as Appellant, ECF No. 48, Ex. A at 9 (providing
the Court with Defendant Apple Inc.’s Notice of Motion in
Uniloc USA v. Apple Inc., 3:18-cv-360 (N.D. Cal. Oct. 25,
2018)).
    Uniloc only partially complied with the court’s order.
While it provided documents related to the May 3 transfer
and licensing agreements between Uniloc 2017 and Uniloc
USA, it neglected to include documents on Uniloc Luxem-
bourg’s patent portfolio before the May 3 transfer. After
Apple uncovered evidence of this deficiency, the district
court again compelled Uniloc to produce all documents in
the related proceedings, “not just 99 percent,” about the
ownership of the patents-in-suit. Tr. of Proceedings held
on Sept. 4, 2018 at 18, Uniloc USA v. Apple Inc., 3:18-cv-
360 (N.D. Cal. Sept. 5, 2018).
4                                  UNILOC USA, INC. v. APPLE INC.




    Uniloc produced documents relating to a loan agree-
ment between Uniloc Luxembourg and Fortress Credit Co.
LLC. Under the loan agreement, Uniloc Luxembourg col-
lateralized its patent portfolio in exchange for a loan. Ac-
cording to Apple, default would give Fortress the right to
transfer or sublicense any of Uniloc’s patents.
     Apple moved to dismiss for lack of subject matter juris-
diction in the pending related cases arguing: (1) no plain-
tiffs currently in the suit had standing to bring an
infringement claim, and (2) Uniloc’s default on the loan
agreement meant that the plaintiffs lacked standing to
bring an infringement claim when they filed for infringe-
ment. Uniloc moved to add Uniloc 2017 as a party to those
cases.
    The district court cured the ongoing jurisdictional de-
fect by adding Uniloc 2017 as a party to the related cases.
And the district court determined that the loan agreement
with Fortress did not deprive Uniloc Luxembourg of stand-
ing to bring those suits when the claims were filed. On Au-
gust 7, 2019, the court denied reconsideration on the
Fortress issue, but stated that “at the final pretrial confer-
ence (and not before), Apple will be allowed to ask that the
issue of default and cure be tried to the jury (or possibly the
judge).” Citation of Supplemental Authority, ECF No. 57,
Ex. A at 1 (providing the Court with Order Den. Mot. for
Recons., Uniloc 2017 LLC v. Apple Inc., 3:18-cv-360 (N.D.
Cal. Aug.7, 2019)).
                              C.
    As to this case, because this case was already on ap-
peal, Apple could not move to dismiss or supplement the
record with its recent discoveries. Uniloc moved under
Federal Rule of Civil Procedure 62.1 for an indicative rul-
ing from the district court indicating that if we remand, the
district court would join Uniloc 2017. Apple opposed this
motion.
UNILOC USA, INC. v. APPLE INC.                             5



    The district court abstained from granting an indica-
tive ruling under Rule 62.1, noting that “[t]he instant mess
is one of [Uniloc’s] own making. The best that the short-
ness of life allows is reference to the companion order in
the related actions addressing Apple’s motion to dismiss
and [Uniloc’s] motion to join Uniloc 2017.” Notice Regard-
ing Decision on Rule 62.1 Mot., ECF 46, Ex. A at 2 (provid-
ing the Court with Order Den. Mot. for an Indicative
Ruling, Uniloc USA, Inc. v. Apple Inc., 3:18-cv-358 (N.D.
Cal. Jan. 17, 2019)).
                                 II
                                 A.
    “Federal courts are not courts of general jurisdiction;
they have only the power that is authorized by Article III
of the Constitution and the statutes enacted by Congress
pursuant thereto.” Bender v. Williamsport Area Sch. Dist.,
475 U.S. 534, 541 (1986). “A party, or the court sua sponte,
may address a challenge to subject matter jurisdiction at
any time, even on appeal.” Booth v. United States, 990 F.2d
617, 620 (Fed. Cir. 1993). “[S]ubject matter jurisdiction
cannot be conferred by waiver, estoppel, or consent.” Diggs
v. Dep’t of Hous. & Urban Dev., 670 F.3d 1353, 1355 (Fed.
Cir. 2011). “[S]tanding is an essential and unchanging part
of the case-or-controversy requirement of Article III.”
Lujan v. Defs. of Wildlife, 504 U.S. 555, 560 (1992).
     “The Patent Act provides that only ‘[a] patentee shall
have remedy by civil action for infringement of his patent.’”
Paradise Creations, Inc. v. UV Sales, Inc., 315 F.3d 1304,
1308 (Fed. Cir. 2003) (quoting 35 U.S.C. § 281). “[W]here
the patentee makes an assignment of all substantial rights
under the patent, the assignee may be deemed the effective
‘patentee.’” Prima Tek II, L.L.C. v. A-Roo Co., 222 F.3d
1372, 1377 (Fed. Cir. 2000). “[I]n order to assert standing
for patent infringement, the plaintiff must demonstrate
that it held enforceable title to the patent at the inception
of the lawsuit.” Paradise Creations, Inc., 315 F.3d at 1309.
6                                 UNILOC USA, INC. v. APPLE INC.




    Apple claims that Fortress may have been the true
owner of the patent at issue when this case was filed. If
true, this would indicate an incurable jurisdictional defect.
But we are an appellate court, and “[a]ppellate review con-
centrates on considering the factual record presented in the
trial courts.” Rosaura Bldg. Corp. v. Municipality of Ma-
yaguez, 778 F.3d 55, 64 (1st Cir. 2015). We restrict our re-
view to the record before the district court when it entered
judgment. Swanson Grp. Mfg. LLC v. Jewell, 790 F.3d 235,
241 (D.C. Cir. 2015). It is “the trial forum,” not us, that is
“vested with authority to determine questions of fact [and
that should have] the opportunity to evaluate all the evi-
dence the parties believe relevant to the issues.” Id.
(cleaned up).
    Uniloc invites us to rely on the record and decisions in
the related cases to resolve the subject matter jurisdiction
issue. It argues that the district court’s denial of Apple’s
motion to dismiss and motion for reconsideration in those
cases are opinions with a record that we can rely on for re-
view. We disagree.
    The record before the district court in the related cases
is not the record before us on appeal. And in any event, the
district court’s opinion is not final. Although the court de-
nied Apple’s motion for reconsideration, it noted that it
would consider jurisdiction again before trial.
     Because the facts relating to the Fortress loan agree-
ment came to light after the district court’s final judgment,
we lack the necessary record to rule on the jurisdictional
issue. And because Apple raised the prospect of a founda-
tional defect in jurisdiction, we must remand for the dis-
trict court to supplement the record and resolve any
outstanding jurisdictional issues.
                             B.
   Apple also argues that the May 3 transfer caused a sec-
ond jurisdictional defect by depriving the court of a named
UNILOC USA, INC. v. APPLE INC.                                7



plaintiff with standing to assert an infringement claim
when it entered final judgment on May 18, 2018. Uniloc
argues that we can remedy this jurisdictional defect on ap-
peal by adding Uniloc 2017 as a party. Apple opposes add-
ing Uniloc 2017 as a party to the appeal, arguing that
remand is more appropriate.
     “[I]f, at the end of the day and case, a jurisdictional de-
fect remains uncured” when the district court enters judg-
ment, “the judgment must be vacated.” Caterpillar Inc. v.
Lewis, 519 U.S. 61, 76–77 (1996). The Supreme Court has
long held that “[t]he profits or damages for infringement
cannot be sued for except on the basis of title as patentee,
or as such assignee or grantee, to the whole or a part of the
patent, and not on the basis merely of the assignment of a
right to a claim for profits and damages, severed from such
title.” Prima Tek II, L.L.C., 222 F.3d at 1381 (parentheti-
cally quoting Crown Die & Tool Co. v. Nye Tool & Mach.
Works, 261 U.S. 24, 42 (1923)). We have held “a ‘right to
sue’ clause cannot confer standing on a bare licensee.” Id.
The license agreement between Uniloc 2017 and Uniloc
USA appears to be little more than a “‘hunting license,’
solely for the purpose of litigation.” See id. Thus, Apple
has a basis for contesting the district court’s jurisdiction at
final judgment.
     Adding a party after judgment to cure a technical ju-
risdictional defect is not a new practice. Mullaney v. An-
derson, 342 U.S. 415, 417 (1952). We have significant
latitude in deciding between adding a party to a pending
appeal or remanding a case for the district court to cure
any jurisdictional defect. Compare Mentor H/S, Inc. v.
Med. Device All., Inc., 244 F.3d 1365, 1373 (Fed. Cir. 2001)
(finding that adding the proper plaintiff during the appeal
would not prejudice the defendant), with Prima Tek II,
L.L.C., 222 F.3d at 1381 (finding that remand was the most
appropriate course given the defendant had raised the is-
sue and may be prejudiced by allowing the real patent
owner to escape discovery).
8                             UNILOC USA, INC. v. APPLE INC.




    We decline to determine whether it is appropriate to
add Uniloc 2017 as a party. Apple opposes the joinder and
determining the propriety of joining Uniloc 2017 involves
reviewing facts that are outside the record. Moreover, be-
cause we must remand the case on the issue relating to the
Fortress loan agreement, we find it appropriate to leave
this issue for the district court to address on remand as
well.
                             III
    We remand this case to the district court for the pur-
pose of supplementing the record with the documents per-
taining to jurisdiction and resolving the presented
jurisdictional issues in the first instance.
                VACATED AND REMANDED
    No costs.
