  United States Court of Appeals
      for the Federal Circuit
                ______________________

       HONEYWELL INTERNATIONAL INC.,
                 Appellant

                          v.

        ARKEMA INC., ARKEMA FRANCE,
                   Appellees
            ______________________

                 2018-1151, 2018-1153
                ______________________

    Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in Nos. PGR2016-
00011, PGR2016-00012.
                 ______________________

               Decided: October 1, 2019
               ______________________

   JOHN C. O'QUINN, Kirkland & Ellis LLP, Washington,
DC, argued for appellant. Also represented by GREGG
LOCASCIO, WILLIAM H. BURGESS, NOAH SAMUEL FRANK,
CALVIN ALEXANDER SHANK.

   MARK J. FELDSTEIN, Finnegan, Washington, DC, ar-
gued for appellees. Also represented by ERIN SOMMERS,
MARK D. SWEET.
                ______________________

  Before NEWMAN, REYNA, and HUGHES, Circuit Judges.
2             HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.




REYNA, Circuit Judge.
     Honeywell appeals from a pair of post-grant review
proceedings involving a single Honeywell patent. Follow-
ing institution, Honeywell sought authorization from the
Board to file a motion for leave to petition the Patent and
Trademark Office Director for a Certificate of Correction to
correct the challenged patent. Honeywell sought to correct
a mistake in the chain of priority listed on the face of the
patent. The Board rejected Honeywell’s request. Because
we conclude that the Board abused its discretion in reject-
ing Honeywell’s request for authorization to file a motion
for leave, we vacate and remand.
                        BACKGROUND
                     I. The ’017 Patent
     Honeywell International Inc. (“Honeywell”) owns U.S.
Patent No. 9,157,017 (“the ’017 patent”), which is directed
to fluoroalkene compounds used in refrigeration systems
and other applications. The ’017 patent issued on October
13, 2015, and recites a chain of priority applications dating
back to 2002, all of which were incorporated by reference
into the ’017 patent.
     During prosecution of the ’017 patent, Honeywell filed
a preliminary amendment that cancelled all 20 claims re-
cited in the original application and added 20 new claims
directed to admittedly different subject matter: automobile
air conditioning systems. In the proceedings below, Hon-
eywell asserted for the first time that when it made the
preliminary amendment, it inadvertently failed to make
corresponding amendments to the list of priority applica-
tions. J.A. 156:10–13 (asserting an “inadvertent error in
failing to make a claim of priority to [certain] sister chains
of cases that we could have made at that time”). As a re-
sult, when the ’017 patent issued, the list of priority appli-
cations listed on the face of the patent was materially the
same as the initial application.
HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.                3



                    II. Arkema’s
          PGR2016-00012 and PGR2016-00011
    Four months after the ’017 patent issued, Arkema Inc.
(“Arkema”) filed two petitions for post-grant review
(“PGR”) of the ’017 patent with the Patent Trial and Appeal
Board (“Board”) of the Patent and Trademark Office
(“PTO”). Both petitions asserted that the priority applica-
tions listed on the face of the ’017 patent did not provide
written description support for the issued claims. As a re-
sult, Arkema argued, the claims of the ’017 patent were
only entitled to a priority date of March 26, 2014—the fil-
ing date of the application that led to the ’017 patent—ra-
ther than the 2002 priority date that would result if the
priority chain adequately supported the claims.
    Based on that contention, Arkema argued that the ’017
patent was eligible for PGR proceedings, which are availa-
ble only for patents having at least one claim with an effec-
tive filing date on or after March 16, 2013. Arkema also
presented several prior art references, including work by
Honeywell’s own inventors, dated from the period between
2002 and 2014.
    According to Honeywell, it did not immediately realize
that the alleged lack of written description support
stemmed from a mistake in the priority chain. Instead, in
its Preliminary Patent Owner Response to Arkema’s peti-
tion, Honeywell argued that all claims of the ’017 patent
were entitled to a priority date at least as early as 2004
based on the priority chain listed on the patent. As a re-
sult, Honeywell claimed, the ’017 patent was not eligible
for PGR proceedings. The Board rejected Honeywell’s ar-
gument and instituted both post-grant review proceedings.
    Honeywell asserts that it realized the priority chain
mistake when preparing its Patent Owner Response. Hon-
eywell then requested permission to file a motion for leave
to request a Certificate of Correction from the Director of
the PTO (“Director”) that would amend the priority chain
4             HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.




of the ’017 patent. Honeywell explained that its proposed
correction would include additional Honeywell patent ap-
plications in the priority chain that disclosed automotive
air conditioning subject matter, and thus conferred a dif-
ferent priority benefit.
    The Board held two telephonic conferences to discuss
Honeywell’s request. In response to questions from the
Board, Honeywell conceded that the mistake was not a
clerical or typographical error, but it argued that a Certifi-
cate of Correction is a permissible means for making “a
change in the priority chain.” J.A. 155:19–22. Honeywell
also argued that this change was “minor” because it did not
change the substance of the claims or the specification.
J.A. 155:13–25. Finally, in response to the Board’s ques-
tions about whether the change would satisfy the “good
faith” requirement of 35 U.S.C. § 255, Honeywell explained
that it learned of the incomplete priority chain for the first
time after the Board issued its decision to institute. Hon-
eywell asserts, and Arkema does not dispute, that Honey-
well sought authorization from the Board to file its motion
for leave “promptly upon discovering the mistake in the
course of preparing its Patent Owner Responses.” Appel-
lant Br. 50–51. Honeywell sought authorization from the
Board a little over a year after the ’017 patent issued and
less than three months after the Board instituted review.
     Arkema, on the other hand, argued that the error was
“not of a minor character and is not proper grounds for cor-
rection.” J.A. 176:15–19. Arkema claimed that allowing
Honeywell to correct this error would be “extremely preju-
dicial,” because, among other things, Arkema’s window to
re-file a PGR with different prior art or different references
had now closed. J.A. 162:4–165:5.
    The Board rejected Honeywell’s request for authoriza-
tion to file a motion for leave, explaining:
    The panel has conferred and has determined at this
    juncture there has been a failure to show that [the]
HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.                   5



    requirements of 255 have been met. This is not a
    typographical or clerical error. It’s been also failed
    [sic] to show that the minor character prong has
    been met. We do not need to reach the issue of
    whether there is a good faith effort here. Further-
    more, we believe that to the extent of showing prej-
    udice in this case, it would be improper to allow
    such a motion to be filed at this juncture, due to the
    prejudice that would arise to [Arkema].
J.A. 177:12–178:2.
    After rejecting Honeywell’s request, the proceedings
continued until the Board issued a combined Final Written
Decision on August 31, 2017. The Board held that
claims 1–20 of the ’017 patent were unpatentable.
    Honeywell timely appealed. We have jurisdiction un-
der 28 U.S.C. § 1295(a)(4)(A).
                         DISCUSSION
     Under the Administrative Procedure Act, we “hold un-
lawful and set aside agency action, findings, and conclu-
sions found to be . . . arbitrary, capricious, an abuse of
discretion, or otherwise not in accordance with law.”
5 U.S.C. § 706(2)(A); see In re Chapman, 595 F.3d 1330,
1336–37 (Fed. Cir. 2010). The Board abuses its discretion
if the decision: (1) is clearly unreasonable, arbitrary, or fan-
ciful; (2) is based on an erroneous conclusion of law; (3)
rests on clearly erroneous fact findings; or (4) involves a
record that contains no evidence on which the Board could
rationally base its decision. Ultratec, Inc. v. CaptionCall,
LLC, 872 F.3d 1267, 1273 (Fed. Cir. 2017).
    As a preliminary matter, we reject Arkema’s assertion
that the Board’s decision is unreviewable under 5 U.S.C.
§ 701(a)(2) as agency action “committed to agency discre-
tion by law.” As we have held, § 701(a)(2) provides a “very
narrow exception” to the presumption of judicial review,
and is applicable only “in those rare instances where
6             HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.




‘statutes are drawn in such broad terms that in a given case
there is no law to apply.’” Hyatt v. U.S. Patent & Trade-
mark Office, 797 F.3d 1374, 1379 (Fed. Cir. 2015). In Ul-
tratec, we reviewed the Board’s refusal to authorize the
patent owner to file a motion during a post-grant proceed-
ing. 872 F.3d at 1271–72. We are unpersuaded by
Arkema’s arguments that we lack the ability to review the
Board’s refusal to grant authorization in this case.
    On the merits of Honeywell’s appeal, we conclude that
the Board abused its discretion by assuming the authority
that 35 U.S.C. § 255 expressly delegates to the Director: to
determine when a Certificate of Correction is appropriate.
     Patentees may petition the Director to issue a Certifi-
cate of Correction to correct in an issued patent “a mistake
of a clerical or typographical nature, or of minor character,
which was not the fault of the Patent and Trademark Of-
fice.” 35 U.S.C. § 255. The patentee must show that the
mistake “occurred in good faith” and that “the correction
does not involve such changes in the patent as would con-
stitute new matter or would require re-examination.” Id.
    When a patentee seeks to correct a patent that is sub-
ject to a post-issuance review proceeding, the patentee
must first file a motion with the Board seeking authoriza-
tion to petition the Director for a Certificate of Correction,
asking the Board to temporarily cede its exclusive jurisdic-
tion over the proceedings. 37 C.F.R. § 1.323; Manual of Pa-
tent Examining Procedure (“MPEP”) § 1485; see also
37 C.F.R. § 42.3(a). Before doing so, the patentee must
seek authorization from the Board to file the motion for
leave—as is the case with all motions filed with the Board.
37 C.F.R. § 42.20(b) (“A motion will not be entered without
Board authorization.”).
     In other words, a patent owner subject to a post-issu-
ance review proceeding must take three steps in order to
file a petition for a Certificate of Correction: (1) seek au-
thorization from the Board to file a motion, 37 C.F.R.
HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.                  7



§ 42.20(b); (2) if authorization is granted, file a motion with
the Board, asking the Board to cede its exclusive jurisdic-
tion so that the patentee can seek a Certificate of Correc-
tion from the Director, 37 C.F.R. § 1.323; MPEP § 1485; and
(3) if the motion is granted, petition the Director for a Cer-
tificate of Correction under 35 U.S.C. § 255. E.g., Plastic
Dev. Grp., LLC v. Maxchief Investments, Ltd., No. IPR2017-
00846, Paper No. 16 at 2 (P.T.A.B. Nov. 13, 2017). After
those three steps are completed, the Director—not the
Board—will evaluate the merits of the patentee’s petition,
including whether the mistake is of “minor character” or
“occurred in good faith.” See 35 U.S.C. § 255.
    Section 255 does not grant the Board authority to de-
termine whether a mistake in an issued patent is of “minor
character” or “occurred in good faith.” 35 U.S.C. § 255.
That authority is expressly granted to the Director. Id.
The Director has not delegated its Section 255 authority to
the Board, but has instead promulgated procedures by
which patentees may seek the Board’s leave to petition the
Director for a Certificate of Correction. 37 C.F.R. § 1.323;
MPEP § 1485.
    The Board has previously recognized that § 255 author-
izes the Director—not the Board—to determine whether a
Certificate of Correction should be issued. E.g., Plastic
Dev. Grp., Paper No. 16 at 2 (“We leave the final determi-
nation on whether a Certificate of Correction should be is-
sued with the Director in accordance with the authority
granted in 35 U.S.C. § 255.”). The Board has likewise rec-
ognized that its review of a patentee’s motion for leave to
seek a Certificate of Correction from the Director does not
involve a decision about the merits of the patentee’s peti-
tion. E.g., United Servs. Auto. Ass’n v. Asghari-Kamrani,
No. CBM2016-00063, Paper No. 10 at 6 (P.T.A.B. August
4, 2016) (“USAA”). In USAA, the Board explained:
    [I]n the instant Decision, we are not deciding
    whether a request for a Certificate of Correction
8               HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.




      should be granted pursuant to 35 U.S.C. § 255, as
      Patent Owner merely is seeking authorization for
      filing such a request. Moreover, we are not the de-
      ciding official for a request for a Certificate of Cor-
      rection.
Id.
    Instead, the Board has previously reviewed motions for
leave to seek a Certificate of Correction from the Director
to “determine whether there is sufficient basis supporting
Patent Owner’s position that the mistake may be correcta-
ble.” Plastic Dev. Grp., Paper No. 16 at 2 (emphasis added).
We hold that this standard of review is appropriate and
consistent with 35 U.S.C. § 255, the relevant Board regula-
tions, e.g., 37 C.F.R. §§ 1.323, 42.20(b), 42.3(a); MPEP
§ 1485, and Congress’s intent that the post-issuance pro-
ceedings created under the America Invents Act provide
the PTO with an “enlarged opportunity to correct its errors
in granting a patent.” Cascades Projection LLC v. Epson
Am., Inc., 864 F.3d 1309, 1311 (Fed. Cir. 2017).
    But in this case, the Board did not review Honeywell’s
motion for leave to seek a Certificate of Correction from the
Director to determine if Honeywell had demonstrated a
“sufficient basis” that the mistake “may” be correctable.
Instead, the Board prohibited Honeywell from even filing a
motion for leave. The Board refused to authorize Honey-
well to file a motion for leave because “at this juncture
there has been a failure to show that [the] requirements of
255 have been met.” J.A. 177:12–15. Specifically, the
Board determined that—based solely on the two telephonic
hearings—Honeywell “failed to show that the minor char-
acter prong has been met.” J.A. 177:17–19. The Board also
explained that “it would be improper to allow such a motion
to be filed at this juncture, due to the prejudice that would
arise to [Arkema].” J.A. 177:22–178:2.
   By requiring that Honeywell “show that [the] require-
ments of 255 have been met” before authorizing Honeywell
HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.                 9



to file a motion for leave to seek a Certificate of Correction
from the Director, the Board abused its discretion. The
Board further abused its discretion by assuming the au-
thority that § 255 delegates to the Director and deciding
the merits of Honeywell’s petition for a Certificate of Cor-
rection.
    As we held in Ultratec, the Board’s abuse of discretion
precipitated additional problems. 872 F.3d at 1273. First,
by evaluating the merits of Honeywell’s § 255 request when
Honeywell was merely requesting authorization to file a
motion for leave to petition the Director, the Board “lacked
the information necessary to make a reasoned decision.”
Id. At that stage, the Board had not seen the language of
Honeywell’s proposed correction to the priority chain lan-
guage of the ’017 patent. Nor had the Board seen any evi-
dence of whether the mistake was inadvertent and made in
good faith or whether the correction prejudiced Arkema.
     The Board also failed to provide an explanation or a
reasoned basis for its decision. Ultratec, 872 F.3d at 1273
(citing Motor Vehicle Mfs. Ass’n of U.S. v. State Farm Mut.
Auto. Ins. Co., 463 U.S. 29, 43 (1983) (“[T]he agency must
examine the relevant data and articulate a satisfactory ex-
planation for its action including a rational connection be-
tween the facts found and the choice made.”)). The Board
provided no explanation for its conclusion that Honeywell
“failed to show that the minor character prong has been
met” or its conclusion that prejudice to Arkema required
denial of Honeywell’s request to file a motion. JA 177:17–
178:6. This failure impedes our meaningful review on ap-
peal. Ultratec, 872 F.3d at 1274 (“For judicial review to be
meaningfully achieved within these strictures, the agency
tribunal must present a full and reasoned explanation of
its decision.”).
    We find nothing in the record, or in the Board’s conclu-
sory decision, that warrants denying Honeywell’s request
to file a motion for leave to petition the Director for a
10            HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.




Certificate of Correction correcting the priority chain of
the ’017 patent. Indeed, as Honeywell notes, the PTO has
previously allowed patentees to correct priority claims
through Certificates of Correction. Carotek, Inc. v. Koba-
yashi Ventures, LLC., 875 F. Supp. 2d 313, 331 (S.D.N.Y.
2012) (“If a patent is issued and contains a mistake, such
as failing to claim priority to an appropriate earlier-filed
patent, regardless of whose fault the mistake is, it may be
corrected by petitioning the PTO for a Certificate of Correc-
tion.”); B. Braun Melsungen AG v. Becton, Dickinson & Co.,
No. 1:16-cv-411, 2017 WL 2531939, at *4 (D. Del. June 9,
2017) (“There is substantial case law supporting Plaintiffs’
position that the PTO has a longstanding practice of cor-
recting priority claims through certificates of correction.”).
The Board never addresses this prior practice, nor does it
explain why Honeywell’s request is different.
    We also express doubt over Arkema’s assertion that
Honeywell knew about the mistake in priority for at least
nine months but, to obtain a strategic advantage, declined
to pursue correction of the mistake. It is unclear how Hon-
eywell would benefit from intentionally delaying its peti-
tion to the Director. Because the Board improperly refused
Honeywell the opportunity to file a motion for leave (and
Arkema the opportunity to file a response), and then failed
to explain its conclusion that a motion for leave would be
improper “due to the prejudice that would arise to Peti-
tioner,” J.A. 177:17–178:6, we are unable to meaningfully
review the parties’ prejudice arguments.
                        CONCLUSION
    We have considered Arkema’s other arguments and
find them unpersuasive. We conclude that the Board erred
by rejecting Honeywell’s request to file a motion for leave
to petition the Director for a Certificate of Correction based
on Honeywell’s failure to “show that [the] requirements of
255 have been met.” We vacate the Board’s final written
decision and remand to the Board. On remand, the Board
HONEYWELL INTERNATIONAL INC. v. ARKEMA INC.               11



should authorize Honeywell to file a motion seeking leave
to petition the Director for a Certificate of Correction. The
Board should then review Honeywell’s motion for leave in
accordance with 37 C.F.R. § 1.323 and MPEP § 1485, in-
cluding to evaluate whether prejudice to Arkema requires
accommodation.
                VACATED AND REMANDED
                           COSTS
    No costs.
