the Regents of the University of California, University of Vienna, Emmanuelle… v. the Broad Institute, Inc., Massachusetts Institute of Technology, President

United States Court of Appeals
for the Federal Circuit
______________________
THE REGENTS OF THE UNIVERSITY OF
CALIFORNIA, UNIVERSITY OF VIENNA,
EMMANUELLE CHARPENTIER,
Appellants
v.
THE BROAD INSTITUTE, INC., MASSACHUSETTS
INSTITUTE OF TECHNOLOGY, PRESIDENT AND
FELLOWS OF HARVARD COLLEGE,
Cross-Appellants
______________________
2022-1594, 2022-1653
______________________
Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. 106,115.
______________________
Decided: May 12, 2025
______________________
J EFFREY A. LAMKEN, MoloLamken LLP, Washington,
DC, argued for appellants. Also represented by L OIS A HN,
KENNETH E. N OTTER , III; E LIZABETH KATHLEEN CLARKE ,
Chicago, IL, SARA MARGOLIS, New York, NY.
RAYMOND N IMROD , Quinn Emanuel Urquhart & Sulli-
van, LLP, New York, NY, argued for cross-appellants. Also
represented by MATTHEW D. R OBSON; HUGH S. BALSAM ,
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REGENTS OF THE UNIVERSITY OF CALIFORNIA v.
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2
STEVEN R. T RYBUS, Troutman Pepper Locke LLP, Chicago,
IL.
______________________
Before R EYNA , HUGHES, and CUNNINGHAM , Circuit Judges.
R EYNA , Circuit Judge.
The Regents of the University of California, the Uni-
versity of Vienna, and Emmanuelle Charpentier (collec-
tively “Regents”) appeal from the Patent Trial and Appeal
Board’s determinations in a patent interference proceed-
ing. The Broad Institute, Massachusetts Institute of Tech-
nology, and the President and Fellows of Harvard College
(collectively “Broad”) conditionally cross-appeal. After re-
solving preliminary motions, the Board issued a final deci-
sion concluding that Broad has priority over Regents with
respect to a CRISPR-Cas9 system that contains a “single-
guide” RNA that edits or cleaves DNA in eukaryotic cells.
We affirm-in-part, vacate-in-part, and remand as to the
main appeal and dismiss as to the cross-appeal.
B ACKGROUND
This appeal involves an invention relating to the adap-
tation of “CRISPR”1 systems to edit eukaryotic DNA. Ap-
pellant Br. 1; Cross-Appellant Br. 20. Scientists at
Regents claim they invented this technology. Appellant
Br. 1–2, 8–22. Scientists at Broad argue they are the true
inventors. Cross-Appellant Br. 1–2, 14–22. As such, this
1 CRISPR (“clustered regularly interspaced short
palindromic repeats”) comprises a family of DNA loci.
J.A. 3051 (U.S. Patent No. 8,697,359, at 15:58–61). A
“CRISPR system” “refers collectively to transcripts and
other elements involved in the expression of or directing
the activity of CRISPR-associated (‘Cas’) genes[.]” Id.
at 16:32–34.
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dispute centers on one of the oldest doctrines in U.S. patent
law, conception.
I.
A. Early Research
CRISPR systems are immune defense systems in pro-
karyotic cells that naturally edit DNA.2 One of the “sim-
plest” types of CRISPR systems, a “Type II CRISPR
system,” uses an RNA sequence, “crRNA,” to guide a pro-
tein to a particular DNA sequence as part of the process of
editing the DNA. J.A. 64098.
Scientists sought to use the natural editing capabilities
of CRISPR systems to edit DNA in eukaryotic cells.
Broad’s and Regents’ scientists claim that, by 2011 or early
2012, they knew CRISPR Type II systems edit DNA using
three components: mature tracrRNA, mature crRNA, and
a protein called “Cas9.” J.A. 74998–99; J.A. 5597–641
(Martin Jinek et al., A Programmable Dual-RNA-Guided
DNA Endonuclease in Adaptive Bacterial Immunity, 337
SCIENCE 816 (2012)) (“Jinek 2012”). According to Regents,
its scientists believed this biological triptych—called a
“CRISPR-Cas9 complex” or “CRISPR-Cas9 system”—could
be used to edit eukaryotic DNA without having to design a
new protein for every new target DNA sequence, as was
necessary when using prior gene-editing tools. Appellant
Br. 4–5.
Regents’ scientists claim that they further simplified
CRISPR-based gene editing in 2012 by linking two RNA
2 Every living organism is one of two types: prokary-
otic or eukaryotic. Prokaryotes are single-celled organisms
lacking a nucleus, such as bacteria, while eukaryotes are
more complex organisms, such as animals and plants,
whose cells possess a nucleus. Appellant Br. 4; Cross-Ap-
pellant Br. 10.
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sequences in the CRISPR-Cas9 system into a single-mole-
cule “chimeric” RNA, called a “single-guide” RNA
(“sgRNA”). J.A. 57592, 67247–48. They claim that they
made a CRISPR-Cas9 system from a sgRNA they designed,
called “chimera A,” and Cas9. Jinek 2012; J.A. 67260–61.
They claim to have used this system to successfully target
and edit DNA in a cell-free in vitro environment.
J.A. 67260–61, 67286–87. As Regents puts it, this system
“simpl[ified]” gene editing by allowing the system to be “re-
programmed by changing the crRNA.” Appellant Br. 7.
Starting in March 2012, Regents’ scientists, directed by
Charpentier, Jennifer Doudna, and Martin Jinek, planned
experiments to show the single RNA CRISPR-Cas9 system
could be used to edit eukaryotic DNA. On March 1, 2012,
Jinek wrote a notebook entry and exchanged emails with
Doudna in which they described the system and experi-
ments using it in mammalian cells, to test if the system
could successfully edit eukaryotic DNA. J.A. 69007–09; see
Regents of the Univ. of Cal. v. Broad Inst., Inc., No. 106,115,
2022 WL 1664028, at *16 (P.T.A.B. Feb. 28, 2022) (“Final
Decision”). On April 11, 2012, Jinek emailed Doudna an
invention disclosure form describing various techniques for
editing eukaryotic DNA using one of two methods, “mi-
croinjection” or expression “vectors,” in various types of eu-
karyotic cells. J.A. 65628–31, 65643–51. After these initial
plans, Regents filed its first provisional patent application,
“P1” (U.S. Patent App. No. 61/652,086), on May 25, 2012.
Regents’ scientists then planned two specific experi-
ments. First, leading up to May 28, 2012, Jinek wrote note-
book entries describing a plan to test the system’s ability
to edit eukaryotic DNA, using expression vector techniques
with human cells. J.A. 69071–77, 67284–85 (Jinek testify-
ing that he “started” these notebook entries “before
May 28, 2012”). Second, on June 28, 2012, Charpentier
and Krzysztof Chylinski, another Regents scientist, ex-
changed emails with two scientists from another labora-
tory, Florian Raible and Kristin Tessmar, describing a
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second plan to test the system using microinjection tech-
niques in “two well-established fish systems”: zebrafish
and medaka fish. J.A. 66308, 66311–13.
B. Testing the System
1. Tests by Other Scientists
Around the time Regents’ scientists drew up their
plans, Regents’ scientists made public announcements in
June 2012, describing the single RNA CRISPR-Cas9 sys-
tem in a conference presentation at the University of Cali-
fornia, Berkeley (“2012 Berkeley Conference
Presentation”) and an article in Science. J.A. 65907,
65915, 65929–34 (Krzysztof Chylinski & Martin Jinek, “A
programmable dual RNA-guided DNA endonuclease in a
Type II CRISPR system,” Presentation at the University of
California, Berkeley, June 2012); Jinek 2012.
Over the remainder of 2012, scientists from laborato-
ries outside of Regents, including scientists at Broad, at-
tempted to use the system to edit DNA in eukaryotic cells.
Of these laboratories outside Regents, five reported success
from July to December 2012, using expression vector or mi-
croinjection techniques. J.A. 53203–06, 15794–807,
79043–44, 47104–27, 75072–95, 75935–58, 76553–56. Re-
gents claims these other scientists learned of the single
RNA CRISPR-Cas9 system from Regents’ scientists’ June
2012 presentation or article. Appellant Br. 15–18.
One of these other laboratories was run by Feng Zhang,
a scientist at Broad. Learning of the CRISPR-Cas9 system
on June 26, 2012, Zhang immediately planned tests using
the system to edit eukaryotic DNA.3 J.A. 75005–07. His
3 According to Regents, Zhang learned of the single
RNA CRISPR-Cas9 system from another scientist, Luciano
Marraffini. Appellant Br. 15. Regents notes Marraffini
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plans described use of Regents’ scientists’ sgRNA, chimera
A, with another Cas9 system of his own design, as well as
expression vector techniques he asserts to have already de-
veloped. J.A. 74999, 75002, 75024–66. Zhang claims that,
on July 20, 2012, he directed the implementation of his
plan on mouse cells. J.A. 75066–72; see also J.A. 75920–
35. He further claims that he soon recognized that the
July 20, 2012 test showed that his Cas9 system success-
fully edited the mouse DNA. J.A. 75073–91; see also
J.A. 75935–58. Zhang claims he then directed repetition of
the experiment and subsequently recognized successful ed-
iting by July 31, 2012. J.A. 75073–91. On October 5, 2012,
Zhang submitted these results to Science, which published
them on January 3, 2013. J.A. 77018–53, 75012–16.
2. Tests by Regents’ Scientists
During the time Zhang and others conducted their ex-
periments, Regents’ scientists performed tests which, ac-
cording to Regents’ scientists, implemented their two
specific plans, as described above. From July through Sep-
tember 2012, Regents’ scientists conducted microinjection
tests in fish embryos, purportedly based on the June 28,
2012 emails between Charpentier, Chylinski, Raible, and
Tessmar. Concurrently, from July through October 2012,
Regents’ scientists conducted expression vector tests in
was a peer reviewer on Regents’ scientists’ manuscript in
Science and emailed a diagram and description of chimera
A to Zhang on June 26, 2012, stating the CRISPR-Cas9
system “would be an important tool for genome editing in
eukaryotes specifically.” Appellant Br. 15–16 (citing
J.A. 77492 and quoting J.A. 80012 (68:13–21)). Broad and
Zhang claim Marraffini learned of the single RNA CRISPR-
Cas9 system from the 2012 Berkeley Conference Presenta-
tion, not the peer review process. Cross-Appellant Br. 17;
J.A. 75052–53.
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human cells, purportedly based on the notebook entries
that Jinek had written before May 28, 2012.
a. Microinjection Tests in Fish Embryos
Regents’ scientists began their microinjection experi-
ments before they began their expression vector experi-
ments. According to Chylinski, Raible and Tessmar were
to perform the microinjection tests in zebrafish and
medaka fish, respectively.4 J.A. 67210. Raible claims that
he conducted the first microinjection test in zebrafish on
July 19, 2012, and that this test did not yield the eyeless
mutation expected from editing. Final Decision, 2022 WL
1664028, at *7 (citation omitted). Raible further claims
that he performed a second set of tests on August 8, 2012,
and that one of these tests yielded “one of roughly 30 em-
bryos” with the “characteristic eyeless morphological phe-
notype expected” from successful editing. J.A. 67122–23.
According to Raible and Chylinski, the two met to discuss
the results the next day, August 9, 2012. J.A. 67122–23,
67214–15. The same day, Chylinski emailed Charpentier
to report “[p]otentially good news about fish” and to indi-
cate that additional changes to the tests “might work but
we shouldn’t be overexcited now.” Final Decision, 2022 WL
1664028, at *8 (citation and quotations omitted); see
J.A. 67214–15.
On August 31, 2012, Chylinski emailed Charpentier
and another colleague with slides reporting further details
of the results from Raible’s August 8, 2012 test.
J.A. 68372–73; see J.A. 67215. One slide, entitled “[f]ish
experiment results,” reported a “[s]mall amount of putative
mutants (1 in 30-50) seen in some of the experiments.”
J.A. 68381. These mutants included “‘[l]ess green’ embryos
4 Tessmar’s tests in medaka fish are briefly refer-
enced in the decision below and not well documented in the
Joint Appendix. Accordingly, we do not discuss them here.
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for Medaka” and “no eyes or misdeveloped eyes for
Zebrafish.” Id. However, the slide stated that these mu-
tants “might be unspecific,” i.e., not due to editing. Id.; see
Final Decision, 2022 WL 1664028, at *9. The slide con-
cluded by noting that “[e]xperiments are still being re-
peated.” J.A. 68381.
Raible claims these results “show[ed] successful cleav-
age [i.e., editing] in a eukaryote using only routine tech-
niques.” J.A. 67128. Accordingly, Raible claims that he
attempted to prove the “efficiency of CRISPR-Cas9” for ed-
iting eukaryotic DNA by conducting at least two more tests
before ending his experimentation on September 12, 2012.
J.A. 67128; Final Decision, 2022 WL 1664028, at *13 (cita-
tion omitted).
b. Expression Vector Tests in Human Cells
While testing with microinjection in fish embryos, Re-
gents’ scientists began simultaneously testing with expres-
sion vectors in human cells. A graduate student claims
that Doudna and Jinek directed him to conduct expression
vector experiments in human cells, starting in early July
2012. J.A. 67467. On August 10, 2012, the student sent an
email reporting the results of tests conducted on July 31
and August 9, 2012. J.A. 67385–86 (citation omitted).
That day, Doudna replied, copying Jinek and stating that
the results of the August 9, 2012 test presented “very ex-
citing” evidence of successful DNA editing. J.A. 67387 (ci-
tation and quotations omitted). By August 13, 2012, Jinek
replied, agreeing that the results were “really exciting.”
J.A. 67302 (citation and quotations omitted). Regents’ sci-
entists claim that Doudna and Jinek instructed the student
to conduct further experiments with some modifications re-
lated to the guide RNA. J.A. 67302, 67387–88, 67499.
After further experiments, on August 16, 2012, the
graduate student sent an email to Doudna and Jinek re-
porting that his most recent results contained no evidence
of editing. J.A. 68467. Under the Regents’ scientists’
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direction, the student continued experimentation in Au-
gust and September 2012, using another expression vector
technique for some of these additional tests. J.A. 67488–
99. In a September 14, 2012 email, the student again re-
ported no evidence of editing. J.A. 68085. Doudna re-
sponded, instructing the student to “simply repeat[] the
original experiment” with one modification, to ensure the
promising results from August 9, 2012 were “repro-
ducib[le]” before changing other “variables.” J.A. 68081.
Doudna also suggested an adjustment to the expression
vector technique. Id.
In late September 2012, according to Regents’ scien-
tists, Doudna and Jinek asked another graduate student to
take over the expression vector tests. J.A. 67315, 67520.
Both students initially collaborated to replicate the Au-
gust 9, 2012 experiment, but, in emails dated October 10,
2012, the students reported no evidence of editing.
J.A. 67520, 69442, 69428. The next day, Doudna replied,
characterizing the latest results as “disappointing” and
questioning if there needed to be further changes to the ex-
pression vector techniques or the “assembly and localiza-
tion” of the single RNA CRISPR-Cas9 system itself.
J.A. 69428, 69439 (referring to “the design and expression
of the guide RNA” and suggesting this “may be the cul-
prit”). Doudna informed the students that she and Jinek
would “be in touch soon about next steps.” J.A. 69439.
Later that same day, Jinek emailed Doudna, “suspect[ing]
we have a problem” with the expression vector techniques
or the “RNA design per se.” J.A. 87705. Over email,
Doudna and Jinek agreed “[i]t would be great to test some
alternate designs of the guide RNA” and to “discuss further
tomorrow.” J.A. 87705, 67065.
According to Doudna, she and Jinek instructed the two
graduate students to continue trying to replicate the Au-
gust 9, 2012 test. J.A. 67396–97 (citations omitted). On
October 19, 2012, Regents filed a second provisional appli-
cation, “P2” (U.S. Patent App. No. 61/716,256). Doudna
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claims that, on October 29, the second student reported ev-
idence of successful editing, and, soon after, reported repli-
cation of this result. J.A. 67397–400 (citations omitted).
II.
Throughout their research efforts, Regents and Broad
filed patent applications relating to CRISPR technology.
Both Regents and Broad claimed in those applications to
be the inventor of the CRISPR technology at issue here,
and, as a result, the Patent Trial and Appeal Board
(“Board”) declared Interference No. 106,115 (“’115 interfer-
ence”), which is the subject of this appeal.5 The ’115 inter-
ference covers Count 1, which recites claim 18 of U.S.
Patent No. 8,697,359 or claim 156 of U.S. Patent Applica-
tion No. 15/981,807. Final Decision, 2022 WL 1664028,
at *4–5. Claim 18 of the ’359 patent recites:
18. The CRISPR-Cas system of claim 15, wherein
the guide RNAs comprise a guide sequence fused to
a tracr sequence.
Id. at *4. Claim 15 of the ’359 patent recites:
15. An engineered, programmable, non-naturally
occurring Type II CRISPR-Cas system comprising
a Cas9 protein and at least one guide RNA that tar-
gets and hybridizes to a target sequence of a DNA
molecule in a eukaryotic cell, wherein the DNA
molecule encodes and the eukaryotic cell expresses
at least one gene product and the Cas9 protein
cleaves the DNA molecules, whereby expression of
the at least one gene product is altered; and,
5 This court previously affirmed the Board’s termi-
nation of a separate interference proceeding that involved
the same parties. See Regents of the Univ. of Cal. v. Broad
Inst., Inc., 903 F.3d 1286, 1289 (Fed. Cir. 2018).
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wherein the Cas9 protein and the guide RNA do not
naturally occur together.
Id. at *4. Claim 156 of the ’807 application recites:
156. A eukaryotic cell comprising a target DNA
molecule and an engineered and/or non-naturally
occurring Type II Clustered Regularly Interspaced
Short Palindromic Repeats (CRISPR) ––– CRISPR
associated (Cas) (CRISPR-Cas) system comprising
a) a Cas9 protein, or a nucleic acid comprising a
nucleotide sequence encoding said Cas9 protein;
and
b) a single molecule DNA-targeting RNA, or a nu-
cleic acid comprising a nucleotide sequence encod-
ing said single molecule DNA-targeting RNA;
wherein the single molecule DNA-targeting RNA
comprises:
i) a targeter-RNA that is capable of hybridizing
with a target sequence in the target DNA molecule,
and
ii) an activator-RNA that is capable of hybridizing
with the targeter-RNA to form a double-stranded
RNA duplex of a protein-binding segment,
wherein the activator-RNA and the targeter-RNA
are covalently linked to one another with interven-
ing nucleotides; and
wherein the single molecule DNA-targeting RNA is
capable of forming a complex with the Cas9 pro-
tein, thereby targeting the Cas9 protein to the tar-
get DNA molecule, whereby said system is capable
of cleaving or editing the target DNA molecule or
modulating transcription of at least one gene en-
coded by the target DNA molecule.
Id. at *4–5.
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Each party filed preliminary motions before the Board,
three of which are relevant to this appeal: two from Broad
and one from Regents. Before ruling on the parties’ pre-
liminary motions, the Board addressed a claim construc-
tion dispute about the claim term “guide RNA.” This term
appears in most of Broad’s claims and is relevant to both of
Broad’s motions. Broad argued that the term “guide RNA”
is “generic,” meaning it is not limited to a single- or dual-
molecule RNA configuration. J.A. 33. The Board disagreed
and determined that the broadest reasonable interpreta-
tion of the claim term “‘guide RNA’ encompasses only a sin-
gle-molecule RNA configuration.” Id. The Board
subsequently addressed each of the parties’ motions in
turn.
First, Broad moved to change the interference count
from Count 1, which covers CRISPR-Cas9 systems that use
sgRNA, to Broad’s proposed “generic” Count 2, which co-
vers both single- and dual-molecule RNA configurations.
J.A. 33–35. The Board determined Broad’s proposed Count
2 included several additional, unexplained changes beyond
the expansion from sgRNA to single- and dual-molecule
RNA configurations. J.A. 35. For example, while Count 1
is directed to a system or a eukaryotic cell, Broad’s pro-
posed Count 2 is directed to a method. J.A. 35. The Board
deemed Broad’s lack of explanation for the additional
changes a major defect and denied Broad’s motion “on this
basis alone.” J.A. 35.
Second, Broad alternatively argued that if the Board
denied its prior motion to change the count, the Board
should remove certain claims from the interference pro-
ceeding. J.A. 41–42. Broad premised its alternative mo-
tion on the assumption that if the Board denied its prior
motion, the Board must have determined that claims to eu-
karyotic CRISPR-Cas9 systems containing sgRNA are sep-
arately patentable from claims to single- and dual-
molecule RNA configurations. The Board disagreed with
Broad’s assumption that the Board made a determination
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about separately patentable inventions and clarified that
it did not reach such a determination. J.A. 43. The Board
asserted that it had denied Broad’s prior motion because
Broad failed to explain the reasons for its proposed changes
to the count. Id. The Board determined that Broad’s mis-
taken assumption led Broad to fail to make a persuasive
argument showing that the claims it sought to remove from
the interference proceeding did not correspond to Count 1.
Id. (citing 37 C.F.R. § 41.207(b)(2)); J.A. 47–53. On this ba-
sis, the Board denied Broad’s alternative motion.
Third, Regents moved to be accorded the benefit of the
May 2012 filing date of its P1 application for purposes of
determining priority.6 J.A. 80. In the alternative, Regents
argued that it should be accorded the benefit of the October
2012 filing date of its P2 application, or the January 2013
filing date of its third provisional patent application, “P3”
(U.S. Patent App. No. 61/757,640). J.A. 105. The Board
determined that neither P1 nor P2 were a constructive re-
duction to practice of Count 1 because neither satisfied the
written description requirement of 35 U.S.C. § 112.
J.A. 104–05. The Board determined that P3 was a con-
structive reduction to practice of Count 1 because P3 suffi-
ciently described and enabled an embodiment of Count 1.
J.A. 106–07. Accordingly, the Board denied Regents’ mo-
tion with respect to P1 and P2 but granted it with respect
to P3. J.A. 107.
6 In an interference proceeding, a party may be ac-
corded the benefit of the filing date of its patent application
if that application is a constructive reduction to practice of
at least one embodiment within the count of the interfer-
ence. Falko-Gunter Falkner v. Inglis, 448 F.3d 1357, 1362
(Fed. Cir. 2006). A constructive reduction to practice must
be a described and enabled (pursuant to 35 U.S.C. § 112)
anticipation of the subject matter of the count.
37 C.F.R. § 41.201.
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As a result of the Board’s resolution of the parties’ pre-
liminary motions, the Board designated Regents as the
junior party and Broad as the senior party for purposes of
the priority phase of the interference proceeding. J.A. 109.
The interference proceeding continued under Count 1.
The Board determined Broad is entitled to priority over
Regents with respect to Count 1. Final Decision, 2022 WL
1664028, at *1. The Board decided Broad reduced to prac-
tice by October 5, 2012, when Zhang submitted the manu-
script to Science.7 Id. at *33. The Board rejected Regents’
earliest asserted date of reduction to practice of August 9,
2012, which was based on emails about Raible’s second mi-
croinjection test.8 Id. at *13–14. It further rejected Re-
gents’ earliest asserted date of conception on March 1,
2012, and later asserted dates through June 28, 2012,
which were based on various disclosures: notebook entries,
emails, and reports surrounding Regents’ microinjection
and expression vector tests. Id. at *24–26. Lastly, the
Board rejected Regents’ assertion that Broad “derived the
system recited in Count 1 entirely from” Regents. Id.
at *34–37.
Regents appeals the Board’s decisions on conception
and written description. Broad conditionally cross-appeals
the Board’s decision on claim construction. We have juris-
diction under pre-America Invents Act
28 U.S.C. § 1295(a)(4)(A). Technical Corrections—Leahy–
7 The Board did not evaluate Broad’s asserted dates
of actual reduction to practice or conception in July and Au-
gust 2012, since it rejected earlier dates Regents asserted
for conception and actual reduction to practice. Id. at *26.
8 The Board did not decide Regents’ other asserted
dates of actual reduction to practice, since they postdated
October 5, 2012, the date by which the Board determined
Broad established actual reduction to practice. Id. at *14.
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Smith America Invents Act, Pub. L. No. 112-274, 126 Stat.
2456, 2458 (2013).
STANDARD OF REVIEW
We set aside agency decisions if they are “arbitrary, ca-
pricious, an abuse of discretion, or otherwise not in accord-
ance with law, and we set aside factual findings that are
unsupported by substantial evidence.” Falkner, 448 F.3d
at 1363 (citations omitted). Substantial evidence is “such
relevant evidence as a reasonable mind might accept as ad-
equate to support a conclusion.” Consol. Edison Co. v.
NLRB, 305 U.S. 197, 229 (1938). We review questions of
law de novo. Falkner, 448 F.3d at 1363.
“Conception and inventorship are ultimately questions
of law that we review de novo[.]” In re VerHoef, 888 F.3d
1362, 1365 (Fed. Cir. 2018), as amended (May 7, 2018).
Conception and inventorship are premised on underlying
fact findings that we review for substantial evidence. Id.
Written description is a question of fact that we review for
substantial evidence. Falkner, 448 F.3d at 1363.
DISCUSSION
I. Conception
Conception is defined as “the formation in the mind of
the inventor, of a definite and permanent idea of the com-
plete and operative invention, as it is hereafter to be ap-
plied in practice.” Burroughs Wellcome Co. v. Barr Lab’ys,
Inc., 40 F.3d 1223, 1228 (Fed. Cir. 1994). “Conception is
complete only when the idea is so clearly defined in the in-
ventor’s mind that only ordinary skill would be necessary
to reduce the invention to practice, without extensive re-
search or experimentation.” Id.
A.
The Board determined that Regents did not prove con-
ception of the invention prior to Broad’s actual reduction to
practice on October 5, 2012, because Regents’ scientists did
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not know their CRISPR-Cas9 system would produce the ef-
fects on genes in a eukaryotic cell recited in Count 1. Final
Decision, 2022 WL 1664028, at *14–26, *33–37. Regents
argues the Board legally erred by requiring Regents’ scien-
tists to know that their invention would work. Appellant
Br. 30–44. We hold that the Board legally erred by conflat-
ing the distinct legal standards for conception and reduc-
tion to practice.
There are three stages to the inventive process: (1) con-
ception, (2) reasonable diligence, and (3) reduction to prac-
tice. Mahurkar v. C.R. Bard, Inc., 79 F.3d 1572, 1577
(Fed. Cir. 1996). At the conception stage, it is well-estab-
lished that “an inventor need not know that his invention
will work for conception to be complete.” Burroughs,
40 F.3d at 1228. Knowledge that the invention will work,
“necessarily, can rest only on an actual reduction to prac-
tice.” Applegate v. Scherer, 332 F.2d 571, 573
(CCPA 1964); see also Univ. of Pittsburgh of Common-
wealth Sys. of Higher Educ. v. Hedrick, 573 F.3d 1290,
1299 (Fed. Cir. 2009) (“Proof that the invention works to a
scientific certainty is reduction to practice.”). The Board
therefore legally erred by requiring Regents’ scientists to
know their invention would work to prove conception.
B.
The Board relied almost exclusively on Regents’ scien-
tists’ statements expressing uncertainty about whether the
experiments had succeeded and suggesting modifications
to their CRISPR-Cas9 system to conclude that they did not
have a “definite and permanent idea.” Final Decision,
2022 WL 1664028, at *22–26 (citing Burroughs, 40 F.3d
at 1229–30). Regents argues that the Board legally erred
by focusing on those statements without considering
whether Regents’ scientists actually and substantively
modified the system. Appellant Br. 30–44. We agree.
Burroughs distinguished between “factual uncer-
tainty . . . that bears on the problem of conception” and
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“general uncertainty surrounding experimental sciences.”
40 F.3d at 1229. Factual uncertainty is when “the subse-
quent course of experimentation, especially experimental
failures, reveals uncertainty that so undermines the speci-
ficity of the inventor’s idea that it is not yet a definite and
permanent reflection of the complete invention as it will be
used in practice.” Id. “[W]hat matters for conception is
whether the inventors had a definite and permanent idea
of the operative inventions,” as evidenced in Burroughs by
the fact that “no prolonged period of extensive research, ex-
periment, and modification followed the alleged concep-
tion.” Id. at 1230. The Board therefore legally erred by
focusing on Regents’ scientists’ statements of uncertainty,
without considering whether those statements led to mod-
ifications in their experiments that substantively changed
their original idea, when determining whether they had a
“definite and permanent idea.” See id.
C.
Regents argues the Board erred by failing to consider
whether scientists at Regents or elsewhere were able to
successfully experiment on Regents’ scientists’ idea using
only “routine skill” or “routine techniques.” Appellant
Br. 35–41. Instead, Regents argues, the Board improperly
“focused solely on [Regents’] purported struggles in reduc-
ing its invention to practice” and related statements of
doubt, taking a “singular focus on inventor success.” Id.
at 35, 37–40.
The key question here is “whether [Regents’ scientists]
had formed the idea of [the invention’s] use for [its in-
tended] purpose in sufficiently final form that only the ex-
ercise of ordinary skill remained to reduce it to practice”
“without extensive research or experimentation.” Bur-
roughs, 40 F.3d at 1228, 1231 (emphasis added). Third-
party evidence of experimental difficulties is relevant to
this inquiry. Amgen, Inc. v. Chugai Pharm. Co., 927 F.2d
1200, 1207 (Fed. Cir. 1991) (in determining there was no
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conception, noting that “several companies, as well as
Amgen and GI, were unsuccessful”). So, too, is third-party
evidence of experimental success using routine skill or
methods. Brand v. Thomas, 96 F.2d 301, 303 (CCPA 1938).
Also relevant is whether an alleged inventor contem-
plated the use of routine skill or methods at an asserted
conception date, or used such routine skill or methods dur-
ing subsequent, successful experimentation conducted by
the alleged inventor. In Burroughs, we credited alleged in-
ventors’ “normal course of clinical trials that mark the path
of any drug to the marketplace” to “confirm[]” that “only
the exercise of ordinary skill remained to reduce [the in-
vention] to practice.” 40 F.3d at 1229–31. Burroughs cited
MacMillan v. Moffett, which determined that the success of
“standard” tests contemplated by an alleged inventor at an
asserted date indicated that he had “thought specifically
about” the use of “available” methods to produce the
claimed invention. 432 F.2d 1237, 1238–39 (CCPA 1970);
see also Lazo v. Tso, 480 F.2d 908, 910–11 (CCPA 1973)
(crediting an alleged inventor’s “master plan” at an as-
serted date, which he then used to obtain “encouraging re-
sults” with a “basic concept of testing”).
The Board erred in its analysis by failing to consider
routine methods or skill, and, instead, focusing almost en-
tirely on Regents’ scientists’ statements about perceived
experimental difficulties and doubts about success. First,
the Board legally erred by expressly refusing to consider
whether a person of ordinary skill in the art could have re-
duced the invention to practice. The Board decided it was
insufficient that Regents’ disclosures only described “the
mechanics of a CRISPR-Cas9 system” and determined that
it was not enough for Regents’ scientists to have “conceived
of the mechanics of” the system; they must have had an
“operative invention.” Final Decision, 2022 WL 1664028,
at *26 (emphases added).
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The Board relied on Hitzeman v. Rutter for the conclu-
sion that “[w]e do not base our decision on a lack of reason-
able expectation of success by [Regents’ scientists as
persons ‘of at least ordinary skill’] that the system would
be capable of editing DNA in a eukaryotic cell,” and that
“we are not persuaded by either party’s evidence of what
those [skilled] in the art expected at the time.” Id. at *24–
26 (citing 243 F.3d 1345, 1358–59 (Fed. Cir. 2001)). In
Hitzeman, we found that a “bare hope” of a result “never
before . . . achieved” is not sufficient to establish concep-
tion. 243 F.3d at 1357. We arrived at this conclusion be-
cause “Hitzeman chose to claim the invention by reciting
the particular result of an intracellular process,” for which
there was no method known by skilled artisans or contem-
plated by Hitzeman that would achieve that result. Id.
at 1356–57 (“[I]t appears that Hitzeman remained unclear
for at least two years after reducing his invention to prac-
tice as to how the particles are formed in yeast.”). We con-
cluded that
the critical deficiency is that Hitzeman specifically
claimed the result of a biological process (i.e., the
expression by yeast of the S-protein, followed by
the assembly of the S-protein into particles) with
no more than a hope, or wish, that yeast would per-
form this assembly process that had never before
been achieved in yeast.
Id. Thus, we held that “complete conception has not oc-
curred” if “a research plan requires extensive research be-
fore the inventor can have a reasonable expectation that
the limitations of the count will actually be met.” Id.
at 1357 (emphasis added). To determine whether an al-
leged inventor “can” reasonably expect reduction to prac-
tice, the court considered the reasonable expectation of a
person of ordinary skill in the art. Id. We focused on
whether “[o]ne skilled in the art at the time” of asserted
conception would “have been able to reasonably predict”
that experimentation would produce the claimed result.
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Id. (citation and quotations omitted) (also considering
whether experimentation would be “reasonably predicta-
ble”).
Unlike in Hitzeman, the claim limitations at issue do
not describe the result of using the single RNA CRISPR-
Cas9 system in a eukaryotic cell, but rather “a single RNA
CRISPR-Cas9 system that functions in eukaryotic cells.”
Final Decision, 2022 WL 1664028, at *2 (emphasis added).
The Board erred by refusing to consider whether a person
of ordinary skill could have achieved the function of editing
eukaryotic DNA. See id. at *24–26. The appropriate anal-
ysis should turn on whether Regents’ scientists “had
formed the idea of their use for that purpose in sufficiently
final form that only the exercise of ordinary skill remained
to reduce it to practice”—more than a “general hope,” but
less than knowing with certainty that the invention would
work. Burroughs, 40 F.3d at 1230–31 (emphasis added).
Second, the Board legally erred in failing to consider
evidence of purported experimental success by others pre-
sented on the record. See Amgen, 927 F.2d at 1206–07. For
example, the Board acknowledged Regents’ argument that,
despite difficulties, “in the end only routine materials and
techniques, as described by” Regents’ scientists, “were re-
quired for a sgRNA CRISPR-Cas9 that can edit DNA in eu-
karyotic cells.” Final Decision, 2022 WL 1664028, at *25.
Elsewhere, the Board rejected Regents’ “attempts to shift
our focus to the activities of other, competing inventors, ra-
ther than the activities of its own inventors.” Id. at *34. It
was legal error for the Board to categorically disregard ev-
idence of purported experimental success by others.
Third, the Board legally erred by failing to consider
whether Regents’ scientists described routine methods or
skill in their disclosures at asserted conception dates, and
whether they used routine methods or skill in subsequent,
purportedly successful experiments. See Burroughs,
40 F.3d at 1229–31; MacMillan, 432 F.2d at 1238–39. The
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Board determined that Regents did not “directly address”
Broad’s argument that Regents’ scientists’ emails during
the experiments in human cells showed that Regents’ sci-
entists “had to redesign their components and strategy be-
yond what would have been routine techniques for one of
ordinary skill in the art.” Final Decision, 2022 WL
1664028, at *21–22. Later, the Board addressed Regents’
argument that Regents’ scientists “had the materials” (i.e.,
the single RNA CRISPR Cas9 system and routine tech-
niques for eukaryotic DNA editing) that were eventually
used to achieve “one unrecognized positive result” in the
zebrafish experiments on August 8, 2012, and to achieve
alleged actual reduction to practice in the human cell ex-
periments by October 31, 2012. Id. at *24. The Board de-
termined that Regents’ scientists “engaged in a ‘prolonged
period of extensive research, experiment, and modification’
following the alleged conception on 1 March 2012,” during
which Regents’ scientists encountered “several failures
with zebrafish embryos and several months of failed exper-
iments and doubt with human cells.” Id. (quoting Bur-
roughs, 40 F.3d at 1230). The Board went on to conclude
that, “[g]iven that the scientists performing these experi-
ments were of at least ordinary skill,” these perceived fail-
ures and doubts showed that Regents’ scientists’ “idea” was
“not yet a definite and permanent reflection of the complete
invention as it [would] be used in practice.” Id. (quoting
Burroughs, 40 F.3d at 1229) (quotations omitted) (empha-
sis added). While the Board mentioned Regents’ argument
that only routine techniques were necessary to achieve re-
duction to practice, the Board did not actually consider
whether, despite subsequent, perceived difficulties and
doubts, Regents’ scientists described routine methods or
skill at the asserted conception dates and used those meth-
ods or that skill to achieve purported successes during sub-
sequent experimentation. This constitutes legal error.
In its analysis, the Board assumed that an alleged in-
ventor’s experimental difficulties must indicate that a
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skilled artisan could not have carried out the invention
without undue experimentation. Final Decision, 2022 WL
1664028, at *24 (citing Burroughs, 40 F.3d at 1230). The
Board determined that conception in this case was not com-
plete due to extensive experimentation, despite acknowl-
edging Regents’ argument that Regents’ scientists had
“described” “routine materials and techniques” and then
used them to successfully “edit DNA in eukaryotic cells.”
Final Decision, 2022 WL 1664028, at *24, *25. However,
we have held that “the existence of research or experimen-
tation does not necessarily indicate, by itself, that complete
conception did not exist,” and that there must be a “nexus
between the research or experimentation and the subject
for which patent protection is sought.” Sewall v. Walters,
21 F.3d 411, 415 n.3 (Fed. Cir. 1994) (citing Bac v. Loomis,
252 F.2d 571, 577 (CCPA 1958)). In Rey–Bellet v. Engel-
hardt, our predecessor court determined that there was
conception, partly due to an absence of “extensive re-
search,” but mainly because a disclosure offered as corrob-
oration required only “routine skill.” 493 F.2d 1380, 1387
(CCPA 1974). There, the Board failed to consider that “the
extent of testing or other research done after the mental
formulation of an invention is not a reliable indicator that
[‘perplexing intricate difficulties’] . . . have been encoun-
tered” that show a skilled artisan could not have reduced
the invention to practice. Id. (citing Alpert v. Slatin,
305 F.2d 891, 894 (CCPA 1962)). In this case, the Board
erred in determining that Regents’ scientists’ experimen-
tation was extensive or undue, without asking whether Re-
gents’ scientists described the use of routine methods or
skill at asserted conception dates, or later used routine
methods or skill to successfully edit eukaryotic DNA.
In sum, the Board erred by failing to consider routine
methods or skill, focusing almost entirely on Regents’ sci-
entists’ perceived experimental difficulties and related
statements of doubt. We thus vacate the Board’s decision
on conception and remand for the Board to decide on
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conception under the proper application of the legal frame-
work.9 On remand, the later party to reduce to practice
will have the opportunity to show, under a conception date
established by the correct standard, either (1) it was “the
first to conceive of the invention and that it exercised rea-
sonable diligence in later reducing that invention to prac-
tice,” Cooper v. Goldfarb, 154 F.3d 1321, 1327 (Fed. Cir.
1998), or (2) it had “prior conception of the claimed subject
matter and communication of the conception to the adverse
claimant.” Price v. Symsek, 988 F.2d 1187, 1190 (Fed. Cir.
1993).
II. Written Description
We turn next to Regents’ challenge to the Board’s writ-
ten description determination. In resolving Regents’ pre-
liminary motion, the Board determined that Regents’ P1
and P2 applications lacked written description support for
Count 1, which covers a single RNA CRISPR-Cas9 system
that functions in eukaryotic cells. Regents argues the
Board applied the wrong legal standard for written descrip-
tion by requiring the P1 application to “convince” a person
of ordinary skill in the art that the invention will work in
eukaryotes.10 Appellant Br. 55–56, 60–66. Regents also
9 Regents also raises an Administrative Procedure
Act (“APA”) challenge to the Board’s conception analysis.
Appellant Br. 47–54. We need not resolve that challenge
because we have determined that vacatur and remand are
warranted as to the Board’s conception analysis.
10 Although Regents argues in passing that its P2 ap-
plication also includes adequate written description sup-
port, Regents does not challenge the Board’s written
description determination for its P2 application on any sep-
arate grounds from its challenge to the Board’s determina-
tion for its P1 application. Appellant Br. 57. We thus only
address P1 for the remainder of this section. See Trading
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separately argues that the Board’s written description
analysis violates the reasoned decision-making require-
ment of the APA. Appellant Br. 47, 54–55. We address
each argument in turn.
Turning to Regents’ first argument, Regents argues the
Board applied the wrong legal standard for written descrip-
tion. Specifically, Regents argues the Board legally erred
by rejecting P1’s identification of the essential components
of the CRISPR-Cas9 complex of Count 1, its explanation of
why the complex works, and its explanation of how to use
the complex in eukaryotes. Appellant Br. 56. Instead, ac-
cording to Regents, the Board required the P1 application
to “convince” a person of ordinary skill in the art that the
invention will work in eukaryotes despite obstacles raised
by Broad. Appellant Br. 55–56, 60–66. We disagree with
Regents that the Board legally erred.
Section 112 of the Patent Act provides that a patent
specification must contain a written description of the in-
vention. 35 U.S.C. § 112(a). To satisfy the written descrip-
tion requirement, a patent’s disclosure must “clearly allow
persons of ordinary skill in the art to recognize that [the
inventor] invented what is claimed.” Ariad Pharms., Inc.
v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en
banc) (alteration in original) (citations omitted). That is,
the test for sufficiency is whether the disclosure “reasona-
bly conveys to those skilled in the art that the inventor had
possession of the claimed subject matter as of the filing
date.” Id. (citations omitted). This test and its concept of
possession requires us to determine how a person of ordi-
nary skill in the art would understand the four corners of
the specification. Id.
Techs. Int’l, Inc. v. IBG LLC, 921 F.3d 1378, 1385 (Fed. Cir.
2019) (“[A] conclusory assertion with no analysis is insuffi-
cient to preserve the issue for appeal.” (citation omitted)).
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Key to this appeal is the well-established principle that
“the level of detail required to satisfy the written descrip-
tion requirement varies depending on the nature and scope
of the claims and on the complexity and predictability of the
relevant technology.” Id. (emphasis added) (citation omit-
ted). When the technology at issue is “complex” and “highly
unpredictable,” as is the case here, the level of detail re-
quired to satisfy the written description requirement may
be greater.11 See, e.g., J.A. 91, 103; Ariad, 598 F.3d
at 1351. Nonetheless, it is also well-established that work-
ing examples or an actual reduction to practice are not nec-
essary to satisfy the written description requirement.
Ariad, 598 F.3d at 1352.
Contrary to Regents’ arguments, the Board did not re-
quire P1 to convince a person of ordinary skill in the art of
the success of Regents’ invention. The Board correctly an-
alyzed whether a person of ordinary skill in the art would
understand that Regents had possession of the claimed
subject matter, given the Board’s uncontested determina-
tion that the subject matter at issue is highly unpredictable
and complex. See J.A. 103. The Board determined that at
the time of filing in 2012, a person of ordinary skill in the
art would have been aware of the complexities and the un-
predictable nature of adapting prokaryotic systems to eu-
karyotic cells. J.A. 88–91. Given that the P1 applicants
failed to disclose specific instructions or conditions neces-
sary for CRISPR-Cas9 activity in a eukaryotic cell, or an
indication that no specific instructions or conditions were
necessary, the Board ruled that a person of ordinary skill
in the art would not understand P1 to show or establish
possession. J.A. 91. In so ruling, the Board properly tai-
lored its analysis to the specific facts of this case, rather
11 Neither party challenges the Board’s determina-
tions about the complexity and predictability of the art on
appeal.
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than applying a one-size-fits-all approach. Ariad, 598 F.3d
at 1351; Capon v. Eshhar, 418 F.3d 1349, 1357–58
(Fed. Cir. 2005). Each case must be decided in relation to
the specific facts and circumstances presented, and that is
what the Board did here.
We note that the Board inquired into whether P1 pro-
vided results of successful working examples. Yet the
Board did not do so to determine whether P1 would con-
vince a person of ordinary skill in the art that the invention
would work. J.A. 103 (recognizing there is no “general re-
quirement” to provide working examples or an expectation
of success). Instead, the Board inquired about working ex-
amples as but one indication, in addition to others, of
whether a person of ordinary skill in the art would under-
stand P1 to establish possession despite the complex and
unpredictable nature of the technology at hand. In doing
so, the Board faithfully applied our precedent. See Capon,
418 F.3d at 1357–58; see also LizardTech, Inc. v. Earth Res.
Mapping, Inc., 424 F.3d 1336, 1345 (Fed. Cir. 2005) (ex-
plaining that “only enough must be included to convince a
person of skill in the art that the inventor possessed the
invention” (emphasis added)). Both in form and in sub-
stance, the Board correctly assessed possession and thus
did not commit legal error.
We turn next to Regents’ APA challenge to the Board’s
written description analysis. Regents argues the Board’s
decision is arbitrary and capricious because in determining
P1 lacks adequate written description support, the Board
exclusively relied on doubts a person of ordinary skill in the
art might have about using only one of the methods pro-
posed by P1—expression vectors—to express the CRISPR-
Cas9 system in eukaryotes. Appellant Br. 54. According
to Regents, the Board never engaged with Regents’ argu-
ment that P1’s disclosure of microinjection, as an alterna-
tive method, would negate those doubts. Id. at 52. Regents
says this is error because a person of ordinary skill in the
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art would understand P1’s disclosure of microinjection to
establish possession. We disagree.
The APA requires agencies to follow a “logical and ra-
tional” process in reaching their decisions. Allentown Mack
Sales and Serv., Inc. v. NLRB, 522 U.S. 359, 374 (1998).
This requirement does not require an agency to “address
every argument raised by a party or explain every possible
reason supporting its conclusion.” Synopsys, Inc. v. Mentor
Graphics Corp., 814 F.3d 1309, 1322 (Fed. Cir. 2016), over-
ruled on other grounds by Aqua Prods., Inc. v. Matal,
872 F.3d 1290 (Fed. Cir. 2017) (en banc).
The Board’s written description analysis satisfies the
APA. The Board thoroughly considered both parties’ argu-
ments and the evidence supporting those arguments.
J.A. 80–107. Many of the parties’ arguments are not spe-
cific to expression vectors or microinjection. J.A. 82 (Broad
arguing that “the unpredictable nature, well-known obsta-
cles, and prior failures and difficulties in adapting prior art
prokaryotic systems to eukaryotic cells” support that P1
lacks written description). And many of the Board’s deter-
minations stand independent of the specific method used,
expression vectors or microinjection, to achieve the inven-
tion. J.A. 81 (Regents “does not direct us to a disclosure in
P1 of results from a CRISPR-Cas system in any of these
eukaryotic cells.”). We see no indication that the Board
limited its written description analysis to using expression
vectors rather than microinjection, as Regents suggests. In
the absence of any such indication, we cannot say that the
Board’s determinations are in fact limited to the use of ex-
pression vectors, nor can we say that the Board’s decision
is arbitrary or capricious. See Regents of the Univ. of Minn.
v. Gilead Scis., Inc., 61 F.4th 1350, 1358–59 (Fed. Cir.
2023).
III. Claim Construction
We turn to Broad’s cross-appeal. The Board deter-
mined that the broadest reasonable interpretation of the
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claim term “‘guide RNA’ encompasses only a single-mole-
cule RNA configuration.” J.A. 33. Broad argues that the
Board’s claim construction analysis is erroneous because
the term “guide RNA” had a plain and ordinary meaning in
the art at the time of filing, and Broad’s patents do not de-
fine the term more narrowly. Cross-Appellant Br. 83–85.
Regents argues Broad’s cross-appeal is moot because the
Board denied Broad’s preliminary motions on inde-
pendently sufficient grounds, unrelated to claim construc-
tion, that Broad does not challenge on appeal. Appellant
Reply Br. 35, 43–48. Broad responds that the Board’s
claim construction necessarily impacted its decisions on
Broad’s preliminary motions. Cross-Appellant Reply
Br. 26. We agree with Regents that Broad’s cross-appeal is
moot.
“The test for mootness is whether the relief sought, if
granted, would make a difference to the legal interests of
the parties.” Acceleration Bay LLC v. 2K Sports, Inc.,
15 F.4th 1069, 1076 (Fed. Cir. 2021) (internal quotations
and citations omitted). Thus, an issue is only moot when
“it is impossible for a court to grant any effectual relief
whatever.” Mission Prod. Holdings, Inc. v. Tempnology,
LLC, 587 U.S. 370, 376–77 (2019) (quoting Chafin v.
Chafin, 568 U.S. 165, 172 (2013)).
Even if we agree with Broad that the Board’s claim con-
struction analysis was erroneous, we could not grant Broad
any effectual relief. The Board’s denial of Broad’s prelimi-
nary motions would remain intact because both rulings
were based on independently sufficient grounds for denial,
irrespective of the Board’s claim construction ruling. Ac-
celeration Bay, 15 F.4th at 1076–77. For Broad’s motion to
change the count, the Board stated that it denied Broad’s
motion irrespective of claim construction. J.A. 35 (denying
Broad’s motion on the independent “basis alone” that
Broad failed to explain all of its proposed changes to the
count). For Broad’s other, alternative motion, the Board
determined Broad’s entire motion was premised on the
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incorrect assumption that the Board must have deter-
mined that claims to eukaryotic CRISPR-Cas9 systems
containing sgRNA are a separately patentable invention
from single- and dual-molecule RNA claims. J.A. 42–43.
This assumption led Broad to fail to make any meaningful
argument as to why any claims it sought to remove from
the interference proceeding would not be anticipated or
rendered obvious by Count 1, regardless of claim construc-
tion. J.A. 42–43, 51–53. Yet Broad chose to only appeal
the Board’s claim construction analysis. Because the relief
sought would not have an impact on the legal interests of
the parties, we must dismiss Broad’s cross-appeal as moot.
C ONCLUSION
For the above reasons, we affirm the Board’s written
description decision and dismiss Broad’s cross-appeal as
moot. We hold that the Board incorrectly applied the legal
standard for conception. We vacate the Board’s determina-
tion as to conception and remand for further proceedings.
On remand, we instruct the Board to reconsider the issue
of conception in a manner consistent with this opinion.
AFFIRMED-IN-PART, VACATED-IN-PART, AND
REMANDED AS TO THE MAIN APPEAL
DISMISSED AS TO THE CROSS-APPEAL
C OSTS
No costs.
Case: 22-1653 Document: 4 Page: 29 Filed: 05/12/2025

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