Miso Transmission Owners v. Federal Energy Regulatory Commission

United States Court of Appeals
FOR THE DISTRICT OF COLUMBIA CIRCUIT
Argued March 17, 2026 Decided June 5, 2026
No. 25-1045
MISO TRANSMISSION O WNERS , ET AL.,
P ETITIONERS
v.
FEDERAL ENERGY R EGULATORY C OMMISSION,
R ESPONDENT
NORRIS ELECTRIC C OOPERATIVE, ET AL.,
INTERVENORS
Consolidated with 25-1066, 25-1069, 25-1115, 25-1124,
25-1126
On Petitions for Review of Orders of the
Federal Energy Regulatory Commission
Christopher R. Jones and Ruth M. Porter argued the
causes for petitioners MISO Transmission Owners, et al. With
them on the joint briefs were C. Dixon Wallace, III, Wendy N.
Reed, and Matthew J. Binette. Abraham F. Johns III and Anne
K. Dailey entered appearances.

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Dana M. Shelton argued the causes for Customer
petitioner. With her on the briefs were Noel J. Darce and
Justin A. Swaim.
Sean A. Atkins, Nicholas J. Cicale, Catherine McCarthy,
Richard L. Roberts, Shaun M. Boedicker, Karen Bruni, Mary
E. Grover, Colin Francis, S. Mark Sciarrotta, Steven M. Nadel,
William M. Keyser, Jeffrey M. Jakubiak, and Melinda Warner
were on the brief for amici curiae in support of Transmission
Owner petitioners.
Jared B. Fish, Senior Attorney, Federal Energy
Regulatory Commission, argued the cause for respondent.
With him on the brief were David L. Morenoff, Deputy General
Counsel, and Robert H. Solomon, Solicitor.
Ruth M. Porter argued the cause for intervenors MISO
Transmission Owners in support of respondent. With her on
the brief were Wendy N. Reed and Matthew J. Binette.
Jeffrey M. Bayne argued the cause for Customers
intervenors in support of respondent. With him on the brief
were James K. Mitchell, Kenneth R. Stark, Matthew L. Garber,
Gerit F. Hull, Jason T. Gray, Noel J. Darce, Dana M. Shelton,
Justin A. Swaim, Stephen C. Pearson, David E. Pomper,
Michael R. Postar, Bhaveeta K. Mody, Andrea I. Sarmentero
Garzon, Kevin M. Kurzeja, Katherine Ann Wade, and James H.
Holt.
Before: P AN and GARCIA , Circuit Judges, and EDWARDS ,
Senior Circuit Judge.
Opinion for the Court filed by Senior Circuit Judge
EDWARDS .

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EDWARDS , Senior Circuit Judge: The petitions for review
in this case involve claims raised by two petitioners
challenging actions taken by respondent Federal Energy
Regulatory Commission (“FERC” or the “Commission”). The
first petitioner includes a group of electric transmission
companies (“Transmission Owners”) doing business within the
province of Midcontinent Independent System Operator, Inc.
(“MISO”). MISO is a non-profit, independent organization that
administers the interstate electric grid in the Midcontinent
region on behalf of Transmission Owners. The second
petitioner is Louisiana Public Service Commission (“LPSC”),
one of many state regulatory commissions within the
Midcontinent region that is overseen by MISO.
This case arises from a long-running dispute over one
component of the rates charged by Transmission Owners to
electricity customers. The disputed component, the return-on-
equity (“Return”), reflects the rate Transmission Owners
receive as compensation for their investments in MISO’s
transmission facilities. On November 12, 2013, a group of
customers filed a complaint with FERC to contest MISO’s
Return as unlawful. That complaint argued that the Return
violated FERC’s obligation to ensure “just and reasonable”
rates under the Federal Power Act (“FPA”). 16 U.S.C.
§§ 824d(a), 824e(a). On February 12, 2015, a second set of
customers filed a separate complaint with FERC challenging
the same Return.
In MISO Transmission Owners v. FERC, 45 F.4th 248
(D.C. Cir. 2022), this court vacated FERC’s initial series of
orders issued in response to those complaints and remanded the
case to FERC to “reopen proceedings.” Id. at 265.
Transmission Owners and LPSC now petition for review of the
orders FERC issued on remand. Transmission Owners argue
that in ordering retroactive refunds with interest for an eight-

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year period, FERC ignored the limits on its authority under
FPA section 206, 16 U.S.C. § 824e. Transmission Owners’
principal claims are that FERC erred in (1) ordering
Transmission Owners to pay years of refunds and interest
beyond what the statute allows; and (2) entertaining a second
complaint that transparently sought only to impermissibly
extend the statutory 15-month limit on refunds under FPA
section 206(b). LPSC, in turn, argues that FERC should have
ordered Transmission Owners to pay more refunds than FERC
deemed reasonable. For the reasons stated below, we deny in
part and dismiss in part Transmission Owners’ petitions for
review, and we deny LPSC’s petitions for review.
I. B ACKGROUND
A. Federal Power Act
Historically, “power grids were run by ‘vertically
integrated monopolies.’” NextEra Energy Res., LLC v. FERC,
118 F.4th 361, 365 (D.C. Cir. 2024) (quoting Midwest ISO
Transmission Owners v. FERC, 373 F.3d 1361, 1363 (D.C. Cir.
2004)). Under that model, a single company owned the
facilities that generated electricity, transmitted it, and
distributed it to customers. See id. “Utilities sold these services
in bundled packages to customers in limited geographic areas.”
Id. By the mid-twentieth century, however, technological
advances enabled new entrants to generate electricity at a lower
cost. See Atl. City Elec. Co. v. FERC, 295 F.3d 1, 4 (D.C. Cir.
2002). Yet, those entrants were largely shut out of the market
because “incumbent utilities used their control of transmission
lines to keep competitors out of the market.” MISO
Transmission Owners, 45 F.4th at 253. “This practice resulted
in artificially high electricity prices for consumers.” NextEra
Energy, 118 F.4th at 365.

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In response, FERC undertook “a restructuring of the
power industry.” Atl. City Elec., 295 F.3d at 4. As part of that
effort, FERC “required utilities to provide open access to their
transmission lines in a nondiscriminatory fashion.” Id. At the
same time, FERC encouraged the development of independent
system operators, neutral entities charged with administering
the grid on a nondiscriminatory basis. See id. at 5.
MISO is one such operator. It is responsible for impartially
managing the transmission grid across the geographic region
spanning from Louisiana to Minnesota and into Manitoba. See
MISO Transmission Owners, 45 F.4th at 253. In return, it
charges customers transmission rates designed to recover costs
and provide transmission owners a reasonable return on their
investment in transmission facilities. Id. This case concerns the
latter component of that rate, the Return.
MISO’s rates, including the Return, are subject to
oversight under the Federal Power Act. See id.; see also FERC
v. Elec. Power Supply Ass’n, 577 U.S. 260, 266 (2016). The
FPA requires FERC to ensure that all rates subject to its
jurisdiction are “just and reasonable” and not “undu[ly]
preferen[tial].” 16 U.S.C. § 824d(a)-(b). That mandate is
implemented through two complementary provisions.
Section 205 permits utilities to propose new rates, which
FERC reviews to determine whether they are lawful. See id.
§ 824d(d)-(e); see also NRG Power Mktg., LLC v. FERC, 862
F.3d 108, 114 (D.C. Cir. 2017).
This case arises under section 206, which authorizes
FERC, upon complaint or on its own motion, to review and
modify existing rates. See 16 U.S.C. § 824e. To do so, FERC
must engage in a two-step inquiry. See Emera Me. v. FERC,
854 F.3d 9, 24 (D.C. Cir. 2017). First, FERC must determine

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whether the existing rate is “unjust” or “unreasonable.” 16
U.S.C. § 824e(a); see also Emera Me., 854 F.3d at 24-25.
Second, if FERC makes such a finding, then it must “determine
the just and reasonable rate . . . to be thereafter observed and in
force” and “fix” that rate “by order.” 16 U.S.C. § 824e(a).
Section 206(a)’s command that the new rate be “thereafter
observed” makes clear that FERC’s ratemaking authority is
prospective. FERC may correct unlawful rates going forward,
but it generally may not revise rates already charged. See City
of Anaheim v. FERC, 558 F.3d 521, 523-24 (D.C. Cir. 2009).
Section 206(b) provides a limited exception for
retrospective monetary relief. That provision requires FERC,
when it institutes a section 206 proceeding in response to the
filing of a complaint, to establish a “refund effective date” that
falls on, or within five months after, the filing of the complaint.
16 U.S.C. § 824e(b). If FERC later determines that the
challenged rate is unlawfully high, it may, at the conclusion of
the proceeding, “order refunds of any amounts paid . . . in
excess of those which would have been paid under the just and
reasonable rate” during the 15 months following the
established refund effective date. Id.
Because the challenged rate remains in effect during the
pendency of the proceeding, customers must continue to pay it.
See MISO Transmission Owners, 45 F.4th at 253. The refund
mechanism allows a limited period of retroactive relief to be
granted. Section 206 strictly prohibits retroactive relief outside
the 15-month refund window. As we have explained,
“[r]efunds of any amounts paid outside of the refund period are
forbidden.” Exxon Mobil Corp. v. FERC, 571 F.3d 1208, 1215
(D.C. Cir. 2009) (internal quotation marks and citation
omitted).

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Section 206 therefore establishes a tightly constrained
remedial scheme. On the one hand, FERC may not permit
utilities to charge unjust or unreasonable rates. On the other, it
may not require utilities to return funds already collected,
except within the limited refund period authorized by section
206(b).
At the same time, the FPA confers a more general grant of
authority that operates alongside those constraints. Section 309
authorizes FERC “to perform any and all acts, and to prescribe,
issue, make, amend, and rescind such orders . . . as it may find
necessary or appropriate to carry out the provisions of [the
FPA].” 16 U.S.C. § 825h. This section “vests the Commission
with broad remedial authority.” Xcel Energy Servs. Inc. v.
FERC, 815 F.3d 947, 954 (D.C. Cir. 2016).
But the authority under section 309 is not unbounded.
Section 309 does not permit FERC to “contravene any terms of
the [FPA]” and “cannot be used to supersede specific statutory
strictures,” TNA Merch. Projects, Inc. v. FERC, 857 F.3d 354,
359 (D.C. Cir. 2017) (citation omitted), such as those provided
by section 206.
As this case shows, there are situations when section 206
and section 309 may be in tension. Petitioners have raised a
legitimate claim here that FERC relied on its authority under
section 309 in a way that appears inconsistent with the refund
limitations imposed by section 206. FERC claims that, given
the circumstances of this case, the two statutory provisions are
not in conflict.
B. Facts and Procedural History
We assume familiarity with the facts and procedural
history of this case, as recounted in our prior opinion, MISO

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Transmission Owners v. FERC, 45 F.4th 248 (D.C. Cir. 2022).
We relate them only as relevant to the present case.
1. Initial Proceedings Before FERC
The petitions before the court arise from a protracted series
of section 206 proceedings before FERC concerning the
lawfulness of the return-on-equity rate administered by MISO.
The proceedings began on November 12, 2013, when a group
of customers filed a complaint (“First Complaint”) under FPA
section 206. The First Complaint challenged, in relevant part,
the 12.38% Return paid to Transmission Owners as “unjust and
unreasonable.” Joint Appendix (“J.A.”) 14 (capitalization
altered); see also J.A. 11. FERC established hearing
procedures before an Administrative Law Judge for the First
Complaint and established a refund effective date of November
12, 2013. Before FERC resolved the First Complaint, however,
a second complaint (“Second Complaint”) raising related
challenges to the same 12.38% Return was filed. FERC
likewise set the Second Complaint for hearing and established
a refund effective date of February 12, 2015.
On September 28, 2016, following a hearing and decision
by an Administrative Law Judge, FERC issued Opinion 551,
in which it resolved the First Complaint. See Ass’n of Bus.
Advocating Tariff Equity v. Midcontinent Indep. Sys. Operator,
Inc., 156 FERC ¶ 61,234 (Sep. 28, 2016) (“Opinion 551”).
There, FERC fixed a new “just and reasonable” Return of
10.32%. Id. ¶ 67, J.A. 882. It also ordered refunds, with
interest, for the 15-month refund period from November 13,
2013 through February 11, 2015. Numerous parties sought
rehearing of Opinion 551.
Before FERC ruled on the rehearing applications or the
Second Complaint, this court issued Emera Maine v. FERC,

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854 F.3d 9 (D.C. Cir. 2017). In Emera Maine, this court held
that FERC had unlawfully collapsed section 206’s required
two-step inquiry by proceeding directly to the selection of a
replacement rate without first determining whether the existing
rate was unjust and unreasonable. See 854 F.3d at 26-27. It thus
vacated the contested actions in Opinions 531, 531-A, and 531-
B. See id. at 30. Because FERC had relied extensively on
Opinion 531 in issuing Opinion 551, it decided to reopen the
First Complaint proceeding.
In Opinion 569, issued on November 21, 2019, FERC
granted rehearing in part of Opinion No. 551. See Ass’n of Bus.
Advocating Tariff Equity v. Midcontinent Indep. Sys. Operator,
Inc., 169 FERC ¶ 61,129 (Nov. 21, 2019) (“Opinion 569”).
Opinion 569 corrected the Emera Maine issue in the First
Complaint proceeding. Accordingly, FERC applied the revised
methodology and found the 12.38% Return to be unjust and
unreasonable. It then established a new Return of 9.88%
effective September 28, 2016, the date of Opinion 551. It
ordered Transmission Owners to provide refunds for the 15-
month refund period from November 12, 2013 through
February 11, 2015 and also from the effective date of the relief,
September 28, 2016, through the date of Opinion 569. Turning
to the Second Complaint, FERC considered whether the
newly-effective 9.88% Return set by the First Complaint
proceeding was just and reasonable and found that it was.
Accordingly, it dismissed the Second Complaint and ordered
no refunds for the corresponding refund period.
Multiple parties sought rehearing of Opinion 569. On May
21, 2020, FERC issued Opinion 569-A, in which it granted in
part the requests for rehearing. See Ass’n of Bus. Advocating
Tariff Equity v. Midcontinent Indep. Sys. Operator, Inc., 171
FERC ¶ 61,154 (May 21, 2020) (“Opinion 569-A”). There,
FERC abandoned portions of the methodology adopted in

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Opinion 569 and reintroduced a risk-premium model that it had
previously rejected. FERC combined that risk-premium model
with methodologies incorporated in Opinion 569 and used the
resulting framework to derive a revised Return of 10.02% in
the First Complaint proceeding. It again made the Return
effective as of September 28, 2016, the date of Opinion 551,
and ordered refunds from then through the date of Opinion
569-A. Additionally, FERC ordered refunds for the 15-month
refund period from November 12, 2013 through February 11,
2015. With respect to the Second Complaint, FERC affirmed
the results of Opinion 569 and again declined to order refunds.
Opinion 569-B, issued on November 19, 2020, corrected
certain inputs to the risk-premium model but otherwise
sustained the results of Opinion 569-A. See Ass’n of Bus.
Advocating Tariff Equity v. Midcontinent Indep. Sys. Operator,
Inc., 173 FERC ¶ 61,159 (Nov. 19, 2020) (“Opinion 569-B”).
2. This Court’s 2022 Decision in MISO
Transmission Owners
Transmission Owners and customer groups separately
petitioned for review of Opinions 551, 569, 569-A, and 569-B,
and those challenges were consolidated for review. In MISO
Transmission Owners, decided August 2022, this court found
that FERC’s decision to reintroduce the risk-premium model in
Opinion 569-A “after initially, and forcefully, rejecting it” in
Opinion 569 was arbitrary and capricious under the
Administrative Procedure Act (“APA”), 5 U.S.C. § 706(2). 45
F.4th at 264. The court explained that although “FERC is . . .
entitled to change its mind[,] . . . it must provide a ‘reasoned
explanation’ for its decision,” and “FERC failed to do that.” Id.
(citation omitted). The court added that “[b]ecause FERC
adopted that significant portion of its model in an arbitrary and
capricious fashion, the new Return produced by that model

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cannot stand.” Id. Thus, the court vacated all four orders and
“remand[ed] for FERC to reopen proceedings.” Id. at 265. It
dismissed Transmission Owners’ petition for review in light of
the vacatur. See id.
In reaching its holding, the court rendered several
additional determinations that are pertinent to the present
proceeding. First, the court acknowledged that it is unlawful
under Emera Maine for FERC to “fail[] to sufficiently explain
why the existing rate [is] unjust and unreasonable at step one
of the [s]ection 206 inquiry,” id. at 261 (citing Emera Me., 854
F.3d at 26-27), as FERC had done in Opinion 551. The court
found that FERC appropriately responded to the error in
Opinion 551 by subsequently adopting a new methodology “to
more effectively verify that an existing rate is in fact unjust and
unreasonable.” Id.
Second, the court held that in resolving the Second
Complaint, FERC had properly used the new Return set by the
First Complaint proceeding rather than the Return in effect at
the time the Second Complaint was filed. See id. at 262. The
court explained that because “the [FPA] uses the present-tense
verb ‘is,’ . . . FERC must look to the current Return at the time
of decision.” Id. It further emphasized that, under the FPA,
FERC must “set a Return ‘to be thereafter observed and in
force.’” Id. Applying that mandate, the court reasoned that
“[o]nce FERC sets a new Return in the first proceeding, it must
observe and enforce that Return until it lawfully changes,
including in ongoing proceedings.” Id.
Third, the court found that FERC’s decision to maintain
an “imperfect correspondence” between “unadjusted betas in
[a third party’s] capital-asset formula” and “adjusted betas for
[FERC’s own] capital-asset formula” was reasonable “based
on the evidence [FERC] had before it.” Id. at 260 (citation

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omitted). The court explained that FERC “had to choose
between ‘imperfect correspondence’ and no size adjustment at
all.” Id. “That is the kind of technical choice to which we are
‘particularly deferential,’” the court explained. Id. (quoting
Pub. Serv. Comm’n of Ky. v. FERC, 397 F.3d 1004, 1006 (D.C.
Cir. 2005)). Thus, the court found that FERC’s decision to
maintain the mismatch between the betas was not arbitrary and
capricious. See id.
Fourth, based on the “same logic,” the court “reject[ed]
the challenge to FERC’s decision to combine adjusted betas
based on the New York Stock Exchange with an expected
return based on the S&P 500.” Id. The court accepted that “it
would not be reasonable [for FERC] to calculate an expected
return using all 2,800 companies in the New York Stock
Exchange.” Id. The court added that “no party provided
adjusted betas from the appropriate time frame based on the
S&P 500.” Id. Thus, FERC had reasonably done “the best it
could with the data it had.” Id.
3. Remand and Rehearing Orders Following the
Court’s August 2022 Decision
Following the issuance of this court’s decision in August
2022, FERC reconsidered the matters at issue and rendered a
Remand Order on October 17, 2024. Ass’n of Bus. Advocating
Tariff Equity v. Midcontinent Indep. Sys. Operator, Inc., 189
FERC ¶ 61,036 (Oct. 17, 2024) (“Remand Order”). In that
order, FERC reversed aspects of the vacated orders criticized
by this court while retaining portions that the court had either
approved or left undisturbed. Applying the approved revised
methodology, FERC undertook the two-step inquiry
necessitated by section 206(a) of the Federal Power Act. At
step one in the First Complaint proceeding, FERC concluded
that the existing 12.38% Return was unjust and unreasonable.

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Proceeding to step two, FERC determined that a just and
reasonable replacement Return was 9.98%. FERC therefore
ordered Transmission Owners to “provide refunds based on
this 9.98% base [Return], with interest, for the First Complaint
proceeding’s 15-month refund period from November 12,
2013, through February 11, 2015, and for the period from
September 28, 2016, to the date of this order.” Id. ¶ 33, J.A.
1799.
Turning to the Second Complaint, FERC noted that this
court had “upheld the Commission’s determinations to treat the
[Return] to be analyzed under the first prong of section 206 in
the Second Complaint as the [Return] that the Commission
fixed as the replacement rate in the First Complaint, rather than
the [Return] in effect at the time the Second Complaint was
filed.” Id. ¶ 34, J.A. 1799. Accordingly, it evaluated whether a
9.98% Return was unjust and unreasonable. FERC found that
it was not. Accordingly, FERC declined to order refunds in the
Second Complaint proceeding.
Transmission Owners and LPSC sought rehearing of the
Remand Order. FERC sustained the results of the Remand
Order in the Rehearing Order issued on March 25, 2025. See
Ass’n of Bus. Advocating Tariff Equity v. Midcontinent Indep.
Sys. Operator, Inc., 190 FERC ¶ 61,184 (Mar. 25, 2025)
(“Rehearing Order”).
Beginning with LPSC’s request for rehearing, FERC
rejected LPSC’s argument that “the Commission should
correct the ‘imperfect correspondence’ in applying a size
premium adjustment based on raw betas to a [capital asset
pricing model] analysis that uses adjusted betas.” Id. ¶ 36, J.A.
1921 (citation omitted). FERC explained that it had “found
that, despite the difference, the size premium adjustment was
still appropriate,” and this court affirmed that approach in

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MISO Transmission Owners. Id. ¶ 37, J.A. 1922. Next, FERC
rejected LPSC’s argument that FERC should match the New
York Stock Exchange betas to the S&P 500 benchmark based
on new evidence LPSC submitted in its request for rehearing.
FERC explained that “[t]he Commission generally does not
allow the introduction of new evidence at the rehearing stage
of a proceeding.” Id. ¶ 42, J.A. 1924. “[F]or the sake of clarity,”
FERC added that LPSC’s proposed data was incomplete and
reaffirmed that its existing methodology was reasonable. Id.,
J.A. 1924-25. Last, FERC rejected LPSC’s contention that
FERC should have resolved the Second Complaint based on
the 12.38% Return in effect during the relevant refund period.
FERC explained that in MISO Transmission Owners, this court
affirmed FERC’s “approach of using the just and reasonable
base [Return] established in the First Complaint as the existing
rate to be analyzed in the Second Complaint.” Id. ¶ 49, J.A.
1928. Thus, FERC reasoned that this court had rejected
LPSC’s argument, and so it did the same.
FERC then turned to Transmission Owners’ request for
rehearing. First, it rejected Transmission Owners’ argument
that FERC had erred by requiring refunds from September 28,
2016 through October 17, 2024, the date of the Remand Order.
FERC explained that its approach “is just and reasonable
because it is dictated by the procedural facts of this proceeding,
and it is necessary to correct a legal error.” Id. ¶ 53, J.A. 1930.
FERC added that its approach is consistent with the authority
provided to the Commission under section 309 of the FPA and
does not run afoul of the 15-month refund limit established in
section 206(b). FERC also rejected Transmission Owners’
argument that FERC should have “dismiss[ed] the Second
Complaint ‘outright’ as an unlawful extension of the [15]-
month refund period in section 206.” Id. ¶ 88, J.A. 1948
(citation omitted). FERC explained that it has permitted
successive complaints where, as here, they rely on new and

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more current financial data. Additionally, FERC noted that
Transmission Owners’ request was moot because FERC did
not order refunds under the Second Complaint.
The following chart summarizes the relevant events.
Date Event Relevant Details
November
12, 2013
First
Complaint
• Challenged 12.38% Return as
unjust and unreasonable
• Refund effective date:
November 12, 2013
February 12,
2015
Second
Complaint
• Challenged 12.38% Return as
unjust and unreasonable
• Refund effective date:
February 12, 2015
September
28, 2016
Opinion 551 First Complaint Proceeding
• New Return = 10.32%
• Effective date of relief:
September 28, 2016
• Refund period: November 13,
2013 – February 11, 2015
Second Complaint Proceeding
• Second Complaint not
addressed in this opinion
April 14,
2017
Emera Maine v.
FERC, 854
F.3d 9 (D.C.
Cir. 2017)
• Vacated Opinion 531, on
which Opinion 551 was based

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November
21, 2019
Opinion 569 First Complaint Proceeding
• Step 1: 12.38% Return =
unjust and unreasonable
• Step 2: New Return = 9.88%
• Effective date of relief:
September 28, 2016 (ordered
refunds from then through
November 21, 2019)
• Refund period: November 12,
2013 – February 11, 2015
Second Complaint Proceeding
• Step 1: 9.88% Return = not
unjust and unreasonable
• Dismissed Second Complaint
• No refunds ordered
May 21, 2020 Opinion 569-A First Complaint Proceeding
• Step 1: 12.38% Return =
unjust and unreasonable
• Step 2: New Return = 10.02%
• Effective date of relief:
September 28, 2016 (ordered
refunds from then through
May 21, 2020)
• Refund period: November 12,
2013 – February 11, 2015

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Second Complaint Proceeding
• Step 1: 10.02% Return = not
unjust and unreasonable
• Dismissed Second Complaint
• No refunds ordered
November
19, 2020
Opinion 569-B • Sustained the results of
Opinion 569-A and corrected
certain inputs to Return
methodology
August 9,
2022
MISO
Transmission
Owners v.
FERC, 45 F.4th
248 (D.C. Cir.
2022)
• Vacated Opinions 551, 569,
569-A, and 569-B
• Remanded to FERC to reopen
proceedings
October 17,
2024
Remand Order First Complaint Proceeding
• Step 1: 12.38% Return =
unjust and unreasonable
• Step 2: New Return = 9.98%
• Effective date of relief:
September 28, 2016 (ordered
refunds from then through
October 17, 2024)
• Refund period: November 12,
2013 – February 11, 2015
Second Complaint Proceeding
• Step 1: 9.98% Return = not
unjust and unreasonable

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• Declined to establish a new
Return
• No refunds ordered
March 25,
2025
Rehearing
Order
• Sustained the results of the
Remand Order
Transmission Owners and LPSC timely petitioned for
review of the Remand Order and Rehearing Order.
II. ANALYSIS
A. Standard of Review
Our review of FERC’s orders under the APA proceeds
along familiar lines. “In general, this court will set aside a
decision [by FERC] only if it is arbitrary and capricious or
otherwise contrary to law.” TNA Merch. Projects, 857 F.3d at
358 (alteration in original) (internal quotation marks and
citation omitted); see also 5 U.S.C. § 706(2)(A), (C). That
inquiry is bounded by a basic principle: “FERC is a creature of
statute” and possesses “only those authorities conferred upon it
by Congress.” Atl. City Elec., 295 F.3d at 8 (citation omitted).
“In the absence of statutory authorization for its act, an
agency’s action is plainly contrary to law and cannot stand.”
Id. (internal quotation marks and citation omitted).
In assessing whether FERC has acted within those bounds,
this court “exercise[s] independent judgment” to reach “the
best reading of the statute.” Loper Bright Enters. v. Raimondo,
603 U.S. 369, 394, 400 (2024). Otherwise, this court
“review[s] FERC’s orders under the deferential arbitrary-and-
capricious standard of review.” LSP Transmission Holdings II,
LLC v. FERC, 45 F.4th 979, 991 (D.C. Cir. 2022). “Under that

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standard, we uphold FERC decisions if the agency has
examined the relevant considerations and articulated a
satisfactory explanation for its action, including a rational
connection between the facts found and the choice made.” Id.
(internal quotation marks and citation omitted). However, a
FERC order will be set aside if it is “unreasonable[] or
inadequately explained.” Id. (citation omitted).
B. Transmission Owners’ Petitions for Review
Transmission Owners petition for review of the Remand
and Rehearing Orders under the APA. They first argue that
FERC exceeded its statutory authority by backdating the
effective date of the Return to September 28, 2016 and ordering
refunds through October 17, 2024, contending that the Federal
Power Act permits only prospective relief and limits refunds to
a 15-month period. They also assert that FERC erred in
permitting successive complaints challenging the same Return,
thereby circumventing that same limitation.
Those arguments fail. First, FERC acted within its
authority in backdating relief to align with the vacatur ordered
in this court’s 2022 decision in MISO Transmission Owners,
which set aside the relevant Return determinations and
authorized a commensurate remedy. Second, Transmission
Owners have not established Article III standing to challenge
FERC’s consideration of a successive complaint, having failed
to show redressability for one injury and imminence for the
other. The petitions are therefore denied in part and dismissed
in part.

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20
1. FERC Lawfully Ordered Refunds from
September 2016 to October 2024
Transmission Owners do not contest FERC’s authority to
order refunds for the 15-month period spanning from
November 12, 2013 to February 11, 2015. After all, FPA
section 206(b) expressly authorizes such relief. Rather, they
challenge FERC’s authority under FPA section 309 to
retroactively apply the new Return effective September 28,
2016 and to order refunds from that date through October 17,
2024. In their view, such a retroactive remedy exceeds FERC’s
statutory authority under the FPA because section 206
authorizes only two forms of relief at the conclusion of a
proceeding: (1) prospective rate adjustments under section
206(a); and (2) “retroactive refunds . . . under section 206(b),
but only for the 15-month period from the refund effective
date.” Br. of Transmission Owners 14 (cleaned up).
As discussed above, Transmission Owners are generally
correct. However, there is a clear exception in play in this case.
Where, as here, FERC is “remedy[ing] its own errors after
being reversed in court[,] . . . ‘[t]his court has . . . recognized
FERC’s authority to order retroactive rate adjustments.’” City
of Anaheim, 558 F.3d at 525 (citation omitted). This exception
applies in a section 206 case, even though it involves a “stricter
set of procedures than section 205” of the FPA. Id. (cleaned
up). Thus, we have observed that in a section 206 proceeding
on remand from this court, FERC may “advanc[e] the
‘effective date’” of a remedy to “cure” a defect identified by
this court. La. Pub. Serv. Comm’n v. FERC, 866 F.3d 426, 430-
31 (D.C. Cir. 2017) (citation omitted). In so finding, this court
added that FERC has “ample authority to remedy its own errors
after being reversed in court, notwithstanding the prohibition
on retroactive ratemaking.” Id. at 431 (emphasis added). This
authority is based in part on the concept that when FERC sets

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21
a new rate that is subject to further review, the relevant
stakeholders are “aware in advance of the risk of litigation-
induced change” and thus on notice that “judicial invalidation
of Commission decisions [could] result[] in retroactive
changes in rates.” W. Deptford Energy, LLC v. FERC, 766 F.3d
10, 22-23 (D.C. Cir. 2014).
This limited exception to the strictures of section 206
plainly applies to the present action. Here, FERC was
responding to this court’s August 2022 decision in MISO
Transmission Owners when it backdated the effective date of
the Return to September 28, 2016. As already explained, the
court determined in MISO Transmission Owners that the
Return set by Opinion 569-A was legally erroneous and
vacated Opinions 551, 569, 569-A, and 569-B as a result. See
45 F.4th at 264. In so holding, the court also tacitly
acknowledged a legal error in Opinion 551, the first opinion
issued in the series, based on this court’s earlier decision in
Emera Maine. See id. at 255, 261.
Because this court invalidated both the initial and
subsequent Return determinations, FERC reasonably
backdated the effective date of the relief ordered to September
28, 2016, the date of Opinion 551, pursuant to its remedial
authority under FPA section 309. Thus, the relief ordered
aligns with the scope of the error identified by this court.
This result makes sense. An alternative approach would
deprive FERC of the ability to give effect to judicial reversals
and would undermine its statutory obligation to ensure just and
reasonable rates. Additionally, “[w]ithout such corrective
power, [regulated parties] would be substantially and
irreparably injured by FERC errors, and judicial review would
be powerless to protect them from much of the losses so

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22
incurred.” TNA Merch. Projects, 857 F.3d at 361 (second
alteration in original) (citation omitted).
Transmission Owners’ arguments to the contrary do not
persuade us to depart from this clear precedent. For example,
they claim that “FERC went far beyond ‘responding to an
adverse court decision’ here when it decided in 2018 to re-open
the hearing, take new evidence, [and] continue to ‘fiddl[e]’
with the [Return] until it finally issued Opinion 569-A.” Reply
Br. of Transmission Owners 13 (second alteration in original).
But Transmission Owners identify no authority to support their
claim that FERC was required to do the bare minimum to
correct its errors. Nor does their argument account for the scope
of this court’s vacatur in MISO Transmission Owners. Because
that decision vacated all four prior opinions in full, any alleged
defects in FERC’s intermediate steps are of no consequence
here. The relevant inquiry for our purposes is whether FERC’s
ultimate remedy appropriately cures the errors identified by
this court. We find that it does.
Additionally, although Transmission Owners mistakenly
argue that FERC’s order of refunds over the contested time
period “finds no support in the statute and is thus ultra vires,”
Br. of Transmission Owners 14, they do not argue that the
effective date selected by FERC was unreasonable. This is
telling. As noted, FERC’s action was within the bounds of
section 309, which authorizes the agency “to perform any and
all acts, and to prescribe, issue, make, amend, and rescind such
orders . . . as it may find necessary or appropriate to carry out
the provisions of [the FPA].” 16 U.S.C. § 825h. We are
satisfied that the refund dates selected by FERC were both
reasonable and consistent with established caselaw, and
Transmission Owners suggest nothing to refute this
conclusion.

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23
This court has “ma[de] it clear that FERC enjoys broad
authority when its past actions are determined to be wrong.”
TNA Merch. Projects, 857 F.3d at 361; see also La. Pub. Serv.
Comm’n, 866 F.3d at 431 (explaining that FERC has “ample
authority to remedy its own errors after being reversed in
court” (emphasis added)). Thus, it was eminently reasonable
for FERC to use its broad authority under section 309 to
backdate the remedy to accord with the scope of MISO
Transmission Owners’ vacatur.
2. Transmission Owners Lack Standing to
Challenge FERC’s Consideration of the Second
Complaint
Transmission Owners also argue that FERC erred in
permitting serial complaints challenging the same Return.
They insist that such successive complaints “circumvent the
FPA’s express [15]-month limit on refunds.” Br. of
Transmission Owners 37 (capitalization altered). “When
petitioners seek direct review of agency action in our court,
they ‘bear[] the burden’ of establishing their standing.”
Entergy Ark., LLC v. FERC, 134 F.4th 576, 580 (D.C. Cir.
2025) (alteration in original) (quoting Twin Rivers Paper Co.
LLC v. SEC, 934 F.3d 607, 613 (D.C. Cir. 2019)).
Transmission Owners have failed to make the requisite
showing for this claim. Thus, we must dismiss it for lack of
jurisdiction.
To establish Article III standing, a petitioner “must have
(1) suffered an injury in fact, (2) that is fairly traceable to the
challenged conduct of the defendant, and (3) that is likely to be
redressed by a favorable judicial decision.” Spokeo, Inc. v.
Robins, 578 U.S. 330, 338 (2016). FERC argues that
Transmission Owners “suffer[ed] no concrete injury . . . from
FERC’s consideration of the Second Complaint” because the

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24
Commission “dismissed that complaint” and “did not order any
refunds stemming from the Second Complaint.” Br. of FERC
65. Transmission Owners respond that they “were subjected to
the costs and burdens of defending against an illegal successive
complaint here and face the real threat of repeatedly being
forced to do so in the future.” Reply Br. of Transmission
Owners 16. But Transmission Owners’ first injury is
concededly not redressable, and their second injury is
concededly not imminent.
First, Transmission Owners claim injury from being
“subjected to the costs and burdens of defending against an
illegal successive complaint here.” Id. (emphasis added). But,
at Oral Argument, Transmission Owners’ counsel represented
that they are not requesting to be refunded for the costs and
burdens already incurred from defending against the Second
Complaint here. See Oral Argument at 35:00-36:30. Rather,
counsel asserted that Transmission Owners seek an order from
this court barring FERC’s future consideration of successive
complaints. See id. But they concede that such an order does
nothing to redress the injury of having to defend against the
Second Complaint here. See id. Thus, Transmission Owners
make no argument that this injury is redressable.
“[R]edressability is an ‘irreducible’ component of standing.”
Uzuegbunam v. Preczewski, 592 U.S. 279, 291 (2021) (quoting
Spokeo, 578 U.S. at 338). Without it, Transmission Owners’
theory of injury premised on the costs and burdens of
defending against the Second Complaint here does not satisfy
the requirements of Article III.
Second, Transmission Owners claim injury from “the real
threat of repeatedly being forced to [defend against a
successive complaint] in the future.” Reply Br. of
Transmission Owners 16. But Transmission Owners bear the
burden of showing that this constitutes an injury that is

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25
“concrete and particularized” and “actual or imminent.” Lujan
v. Defs. of Wildlife, 504 U.S. 555, 560 (1992) (citation
omitted). “[I]mminence” requires “that the injury
is certainly impending.” Clapper v. Amnesty Int’l USA, 568
U.S. 398, 409 (2013) (quoting Lujan, 504 U.S. at 565 n.2).
“Thus, [the Supreme Court] ha[s] repeatedly reiterated that
‘threatened injury must be certainly impending to constitute
injury in fact,’ and that ‘[a]llegations of possible future injury’
are not sufficient.” Id. (third alteration in original) (quoting
Whitmore v. Arkansas, 495 U.S. 149, 158 (1990)).
Transmission Owners fail to make the requisite showing.
They claim there is a “real threat” that they will “repeatedly
be[] forced” to “defend[] against an illegal successive
complaint . . . in the future.” Reply Br. of Transmission Owners
16. While it is, of course, possible that Transmission Owners
will be called to defend against a successive complaint in the
future, they offer no evidence that such injury is likely, much
less certainly impending. See Util. Workers Union of Am. Local
464 v. FERC, 896 F.3d 573, 577 (D.C. Cir. 2018) (“Where, as
here, a case comes to us on a petition directly from an agency,
the petitioner[] . . . must support each element of its claim to
standing by affidavit or other evidence, including whatever
evidence the administrative record may already contain.”
(internal quotation marks and citation omitted)).
In sum, Transmission Owners fail to satisfy the court that
the threat of having to defend against successive complaints is
actual or imminent enough to satisfy the requirements of
Article III standing. We thus must dismiss this claim for lack
of jurisdiction.

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26
C. Louisiana Public Service Commission’s Petitions for
Review
LPSC also petitions for review of FERC’s orders issued
on remand. LPSC first argues that FERC acted contrary to law
in relying on the 9.98% Return established in the First
Complaint proceeding rather than the 12.38% Return in effect
when the Second Complaint was filed. It also contends that
FERC acted arbitrarily and capriciously in maintaining a
mismatch in beta inputs and in rejecting additional data LPSC
submitted on remand. LPSC has standing to press its claims,
but the claims lack merit.
LPSC’s challenge to FERC’s use of the 9.98% Return is
foreclosed by the law-of-the-case doctrine. The court’s
decision in MISO Transmission Owners makes it clear that
FERC must apply the Return in effect at the time of decision,
including in related proceedings. That same decision also bars
LPSC’s renewed attack on FERC’s use of “mismatched” betas,
which MISO Transmission Owners upheld as a reasonable
technical judgment. Finally, FERC reasonably declined to
consider LPSC’s newly submitted data because it was
introduced too late in the proceedings. Accordingly, we deny
LPSC’s petitions for review.
1. LPSC Established Its Standing
As a threshold matter, FERC challenges LPSC’s standing
to press its claims. But, as LPSC makes obvious and
irrefutable, it has Article III standing because its customers are
directly subject to the rates established by the challenged
orders.
As discussed, a petitioner “seek[ing] direct review of
agency action in our court . . . bear[s] the burden of establishing

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27
[its] standing.” Entergy Ark., 134 F.4th at 580 (internal
quotation marks and citation omitted). Because “ordinary rules
of forfeiture apply to standing,” arguments “raised for the first
time in reply” are generally forfeited. Id. at 581 (quoting Twin
Rivers, 934 F.3d at 615). Accordingly, a petitioner must
establish standing in its opening brief. See Sierra Club v. EPA,
292 F.3d 895, 900 (D.C. Cir. 2002).
“We have ‘codified’ these principles in Circuit Rule
28(a)(7).” Entergy Ark., 134 F.4th at 581 (citation omitted).
The revised rule, effective August 11, 2025, requires a
petitioner’s opening brief to “set forth the basis for the claim
of standing” and to include “arguments and cite evidence
establishing by a ‘substantial probability’ the claim of
standing.” D.C. Cir. R. 28(a)(7) (2025) (citing Sierra Club v.
EPA, 292 F.3d at 898).
We have, however, recognized limited exceptions to these
rules. For example, we have permitted petitioners to cure
deficiencies in a reply brief where the “reply brief fleshes out
a timely raised theory of standing and also makes standing
‘patently obvious and irrefutable.’” Sierra Club v. U.S. DOE,
107 F.4th 1012, 1015 (D.C. Cir. 2024) (quoting Twin Rivers,
934 F.3d at 614-15). Where standing is that clear, we may be
assured “that the government suffered no prejudice from the
lateness of the petitioner’s showing.” Id. Although the recent
amendment to Rule 28(a)(7) eliminated one prior exception, it
does not disturb this principle. Cf. Entergy Ark., 134 F.4th at
582 n.3 (explaining that the amendment to Rule 28(a)(7)
removed the textual predicate for a different and inapplicable
exception). LPSC succeeds in establishing that its standing is
“patently obvious and irrefutable” on reply.
The Federal Power Act permits “[a]ny party to a
proceeding under this chapter aggrieved by an order issued by

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28
the Commission in such proceeding” to obtain judicial review
of that order. 16 U.S.C. § 825l(b). “In addition, a petitioner
‘must satisfy the requirements of constitutional standing.’”
Miss. Valley Gas Co. v. FERC, 68 F.3d 503, 507 (D.C. Cir.
1995) (citation omitted). “Both of these thresholds require that
[the petitioner] establish ‘injury in fact’ to a protected interest.”
Id. (citation omitted).
In its opening brief, LPSC explains that it was “aggrieved
by orders issued by FERC because the orders that are the
subject of the LPSC’s petitions for review result in increased
rates for certain LPSC-jurisdictional customers.” Br. for LPSC
17. On reply, LPSC elaborates that the Return set by the
Remand Order is an “inflated” rate and that “customers that
pay a higher, unlawful rate suffer economic injury.” Reply Br.
for LPSC 4. LPSC adds that “[i]n a compliance filing to
effectuate FERC Opinion Nos. [sic] 569-A and Opinion No.
569-B, the Transmission Owners provided FERC with revised
. . . records” listing at least one LPSC customer as subject to
the disputed rates. Id. at 5 (emphasis removed). LPSC adds that
FERC accepted this filing. See id. at 5-6 (citing J.A. 1975-77).
Thus, LPSC explains, its “standing is patently obvious.” Id. at
4. We agree.
The FPA authorizes “[a]ny party . . . aggrieved” by a
FERC order to seek judicial review, 16 U.S.C. § 825l(b), and
LPSC readily meets that standard. So too does it satisfy the
requirements of Article III injury-in-fact. The record shows
that at least one LPSC-jurisdictional customer is subject to the
Return set by the orders on review. Moreover, at oral argument,
FERC’s counsel did not doubt that any of LPSC’s customers
are, in fact, subject to the disputed rates.
We have found that “injury in fact” is “clearly
demonstrated” where FERC orders challenged by the

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29
petitioner “affect the rates it will pay . . . and are directly within
the authority conferred upon FERC.” Miss. Valley Gas, 68 F.3d
at 508. Additionally, as discussed in greater detail below,
LPSC raises essentially the same claims as the customer
petitioners in MISO Transmission Owners. LPSC even argues
substantially the same theory of standing as at least some of the
customer petitioners. And, in MISO Transmission Owners, the
court did not doubt any of the customers’ standing. In fact, this
court subsequently confirmed that MISO Transmission Owners
“involved concrete, imminent harm[] because of . . .
overcharges on rates.” Indus. Energy Consumers of Am. v.
FERC, 125 F.4th 1156, 1161-62 (D.C. Cir. 2025).
LPSC’s injury is also indisputably “‘fairly traceable’ to the
FERC orders, and not the result of independent choices by a
party not before the [c]ourt.” Nw. Requirements Utils. v. FERC,
798 F.3d 796, 806 (9th Cir. 2015) (citation omitted); see also
Lujan, 504 U.S. at 560 (explaining the requirement that an
injury “be fairly traceable to the challenged action of the
defendant, and not the result of the independent action of some
third party not before the court” (cleaned up)). Last, LPSC
“meets the remaining criterion for Article III standing because
it is likely that its alleged injury could be redressed by a
favorable decision from this court.” Miss. Valley Gas, 68 F.3d
at 508. Thus, we are satisfied that LPSC’s standing is so
“patently obvious and irrefutable . . . that [FERC] suffered no
prejudice from the lateness of the petitioner’s showing.” Sierra
Club v. U.S. DOE, 107 F.4th at 1015 (internal quotation marks
and citation omitted). However, while LPSC has standing to
press its claims, those claims all fail for the reasons discussed
below.

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30
2. Law-of-the-Case Bars LPSC’s Challenge to
FERC’s Resolution of the Second Complaint
LPSC asserts that FERC unlawfully decided the Second
Complaint based on the 9.98% Return produced in the First
Complaint proceeding, rather than the 12.38% Return that was
in effect when the Second Complaint was filed. However, the
decision in MISO Transmission Owners resolved this precise
question. LPSC’s claim is thus barred by law-of-the-case
doctrine.
The central premise of the law-of-the-case doctrine is that
“the same issue presented a second time in the same case in
the same court should lead to the same result.” LaShawn A. v.
Barry, 87 F.3d 1389, 1393 (D.C. Cir. 1996) (en banc). Where,
as here, “there is an appeal from the [agency’s] judgment
entered after remand, the decision on the first appeal
establishes the law of the case to be followed on the second.”
U.S. Off. of Pers. Mgmt. v. Fed. Lab. Rels. Auth., 905 F.2d 430,
434 (D.C. Cir. 1990) (citation omitted). In adopting such a rule,
we explained that “an appellate court cannot efficiently
perform its duty to provide expeditious justice to all if a
question, once considered and decided by it were to be litigated
anew in the same case upon any and every subsequent appeal.”
Id. (cleaned up). Such a rule “also discourages ‘panel
shopping’ at the circuit level.” Id. (citation omitted).
“The Supreme Court has instructed the lower courts to be
‘loathe’ to reconsider issues already decided ‘in the absence of
extraordinary circumstances such as where the initial decision
was “clearly erroneous and would work a manifest injustice.”’”
LaShawn A., 87 F.3d at 1393 (quoting Christianson v. Colt
Indus. Operating Corp., 486 U.S. 800, 817 (1988)). No such
circumstances are present here, and, thus, we decline to
reconsider the following issues.

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31
Here, LPSC argues that FERC unlawfully decided the
Second Complaint based on the 9.98% Return produced by the
First Complaint proceeding, rather than the 12.38% Return that
was in effect when the Second Complaint was filed. But, as
discussed, the court in MISO Transmission Owners squarely
rejected the same argument. The court held that FERC properly
used the new Return established by the First Complaint
proceeding to resolve the Second Complaint. See MISO
Transmission Owners, 45 F.4th at 262. It explained that
“[o]nce FERC sets a new Return in the first proceeding, it must
observe and enforce that Return until it lawfully changes,
including in ongoing proceedings.” Id.
On remand, FERC followed that instruction. It thus
resolved the Second Complaint using the Return “that the
Commission fixed as the replacement rate in the First
Complaint, rather than the [Return] in effect at the time the
Second Complaint was filed.” Remand Order ¶ 34, J.A. 1799.
Applying that methodology, it found “that the 9.98% base
[Return] established in the First Complaint proceeding ha[d]
not been shown to be unjust and unreasonable.” Id. ¶ 35, J.A.
1800. Accordingly, FERC concluded “that no refunds w[ould]
be ordered in the Second Complaint proceeding.” Id. ¶ 42, J.A.
1802.
LPSC seeks to relitigate FERC’s methodology in
resolving the Second Complaint. But because this issue was
“already decided” and LPSC presents no “extraordinary
circumstances” to compel our reconsideration, we decline to
depart from MISO Transmission Owners’ holding. LaShawn
A., 87 F.3d at 1393 (citation omitted). The prior panel resolved
the issue, and FERC relied on its guidance in the Remand
Order and Rehearing Order. To permit LPSC to relitigate this
issue where no extraordinary circumstances are present would
undoubtedly prevent this court from “efficiently perform[ing]

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32
its duty to provide expeditious justice to all.” Off. of Pers.
Mgmt., 905 F.2d at 434 (citation omitted).
3. Law-of-the-Case Bars LPSC’s Challenge to
FERC’s Use of Mismatched Betas
LPSC next argues that FERC improperly maintained a
“mismatch between betas used in the base capital-asset model
and those applied in the size premium adjustment calculation”
in the Remand Order, as affirmed by the Rehearing Order. Br.
for LPSC 37 (capitalization altered). According to LPSC, this
conceded “‘imperfect correspondence’ is inconsistent with the
evidence, arbitrary, and should be remanded.” Id. (quoting
Rehearing Order ¶ 38, J.A. 1922). But that argument is
foreclosed by this court’s decision in MISO Transmission
Owners, which upheld the same methodology that FERC
employed here.
In Opinions 569, 569-A, and 569-B, FERC used adjusted
betas in its base capital-asset pricing model while applying a
size premium derived from unadjusted betas. The court in
MISO Transmission Owners held that FERC’s decision to
maintain that “imperfect correspondence” was reasonable
“based on the evidence [FERC] had before it.” 45 F.4th at 260.
Because FERC “had to choose between ‘imperfect
correspondence’ and no size adjustment at all,” the court
deferred to FERC’s judgment on that “kind of technical
choice” and concluded that FERC’s approach was not arbitrary
and capricious under the APA. Id.
On remand, FERC declined to “make any changes to the
[capital asset pricing model] analysis that was used in Opinion
Nos. 569-A and 569-B.” Remand Order ¶ 38, J.A. 1801. LPSC
sought rehearing, asserting that the court in MISO
Transmission Owners had “mistakenly concluded” the record

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33
did not allow the mismatch to be corrected. J.A. 1865. It
therefore directed FERC to data it claimed would eliminate the
issue. FERC rejected LPSC’s reading, explaining that the court
did not assume a lack of evidence but instead upheld the
Commission’s judgment to retain the size adjustment despite
the mismatch. See Rehearing Order ¶ 38, J.A. 1922. FERC
further noted that the data LPSC invoked “was already in the
record,” and thus was before the court in MISO Transmission
Owners. Id. ¶ 39, J.A. 1922-23. Accordingly, FERC found that
LPSC “ha[d] not provided a reason for the Commission to
reach a different determination” and declined to revisit the
issue. Id., J.A. 1923.
LPSC continues to press the matter before the court. But
MISO Transmission Owners already upheld FERC’s approach
as reasonable on the record, and LPSC identifies no
extraordinary circumstances that warrant our reconsideration.
We, therefore, decline to revisit the issue under law-of-the-case
doctrine.
LPSC responds that “MISO [Transmission Owners] . . .
only decid[ed] that the use of the size premium adjustment was
not unjust and unreasonable despite the imperfect
correspondence,” and not “whether the betas in the base
capital-asset model should be corrected.” Reply Br. for LPSC
21. But the court did not cabin its analysis so narrowly. Rather,
it upheld FERC’s decision to retain an “imperfect
correspondence” after considering both the mismatch and
whether it could be eliminated. By sustaining that approach,
the court necessarily rejected any requirement for FERC to
conform the betas.
LPSC “concedes” that if the court already considered that
possibility, “the issue is likely barred.” Id. Because we find that
the court did engage in such consideration, we agree that

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34
LPSC’s challenge is foreclosed by the law-of-the-case
doctrine.
4. FERC Reasonably Rejected LPSC’s Late-Filed
Evidence
Finally, LPSC contends that FERC acted arbitrarily and
capriciously in rejecting its proposed S&P 500-based beta data,
which it submitted on remand to address the evidentiary gap
identified in MISO Transmission Owners. It argues that
FERC’s dismissal of that evidence was insufficiently reasoned
and that FERC could not rely on procedural objections after
choosing to address the submission.
Those arguments fail. FERC reasonably declined to
consider LPSC’s evidence because it was submitted too late.
FERC explained that it “generally does not allow the
introduction of new evidence at the rehearing stage of a
proceeding, as it disrupts the administrative process and
prevents other parties from responding.” Rehearing Order ¶ 42,
J.A. 1924. That approach is consistent with this court’s
precedent. We have held that FERC “has no obligation to
consider new factual evidence that petitioners failed to submit
prior to their petitions for rehearing.” Exxon Corp. v. FERC,
114 F.3d 1252, 1260 (D.C. Cir. 1997). Because LPSC was
aware of the relevant issues earlier in the proceedings, FERC
acted within its discretion in refusing to reopen the record at
the rehearing stage.
Given that dispositive ground, we need not address
FERC’s alternative rationale for rejecting the evidence. An
agency does not forfeit a valid and independently sufficient
ground by also explaining why the same evidence would fail
on the merits. See Salt River Project Agric. Improvement &
Power Dist. v. United States, 762 F.2d 1053, 1061 n.8 (D.C.

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35
Cir. 1985) (“When it is clear that based on the valid findings
the agency would have reached the same ultimate result, we do
not improperly invade the administrative province by
affirming.”). Thus, FERC’s decision to comment on the merits
of the submission “for the sake of clarity” does not undermine
its procedural ruling. Rehearing Order ¶ 42, J.A. 1924.
Accordingly, FERC’s decision not to consider LPSC’s
late-filed evidence was not arbitrary or capricious.
III. CONCLUSION
For the reasons stated above, we deny in part and dismiss
in part Transmission Owners’ petitions for review.
Additionally, we deny LPSC’s petitions for review.
So ordered.

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