Louisiana Public Service Commission v. FERC ( 2021 )


Menu:
  •  United States Court of Appeals
    FOR THE DISTRICT OF COLUMBIA CIRCUIT
    Argued December 10, 2020           Decided August 20, 2021
    No. 20-1024
    LOUISIANA PUBLIC SERVICE COMMISSION,
    PETITIONER
    v.
    FEDERAL ENERGY REGULATORY COMMISSION,
    RESPONDENT
    ENTERGY SERVICES, LLC AND ARKANSAS PUBLIC SERVICE
    COMMISSION,
    INTERVENORS
    On Petition for Review of Orders of the
    Federal Energy Regulatory Commission
    Michael R. Fontham argued the cause for petitioner. With
    him on the briefs were Dana M. Shelton and Justin A. Swaim.
    Lona T. Perry, Deputy Solicitor, Federal Energy
    Regulatory Commission, argued the cause for respondent.
    With her on the brief were David L. Morenoff, Acting General
    Counsel, and Robert H. Solomon, Solicitor.
    Glen Ortman, Dennis Lane, Gregory W. Camet, Mark
    Strain, and Marnie A. McCormick were on the brief for
    intervenors Entergy Services, LLC and Arkansas Public
    2
    Service Commission in support of respondent. Jennifer S.
    Amerkhail and Marie Denyse Zosa entered appearances.
    Before: HENDERSON, PILLARD, and KATSAS, Circuit
    Judges.
    Opinion of the Court filed by Circuit Judge KATSAS.
    KATSAS, Circuit Judge: The Federal Energy Regulatory
    Commission required Entergy Corporation’s five operating
    companies to roughly equalize their electricity production
    costs. In determining which costs must be equalized, FERC
    excluded purchased-power costs that a Louisiana affiliate
    incurred in 2005 and amortized in 2008 and 2009. The agency
    reasoned that the governing tariff excluded the disputed
    amortization expenses.      The Louisiana Public Service
    Commission (LPSC) challenges this exclusion.
    I
    Entergy, a public-utility holding company, owns five
    operating companies that sell electricity in four states,
    including Louisiana. The companies have been governed by a
    system agreement requiring them to act as a “single economic
    unit.” LPSC v. FERC, 
    184 F.3d 892
    , 894 (D.C. Cir. 1999)
    (LPSC I). The agreement provided for the companies to
    operate power facilities jointly, and it required a “rough
    equalization” of their production costs. LPSC v. FERC, 
    522 F.3d 378
    , 383–84 (D.C. Cir. 2008) (LPSC II) (cleaned up).1
    FERC has long reviewed the operating companies’
    allocation of production costs, which affect electricity rates.
    See LPSC II, 
    522 F.3d at 389
    –90. In 2005, FERC determined
    1
    The agreement terminated in August 2016, after the events
    underlying this petition.
    3
    that the production costs were not roughly equal and imposed
    a “bandwidth remedy” to achieve rough equalization after the
    fact: Whenever the yearly production costs of an individual
    operating company deviated from the average by more than
    11%, companies with lower costs were required to pay
    companies with higher costs as necessary to bring all five
    companies within that range. LPSC, 111 FERC ¶ 61,311,
    PP 28, 145 (2005). Although FERC initially made the
    bandwidth remedy effective in 2006, we set aside that effective
    date in 2008. See LPSC II, 
    522 F.3d at 400
    . In 2011, on
    remand from this Court, FERC extended the bandwidth remedy
    to production costs incurred on or after June 1, 2005. See
    LPSC, 137 FERC ¶ 61,047, P 34 (2011).
    In the meantime, Entergy filed a tariff establishing a
    formula to calculate production costs subject to the bandwidth
    remedy, which FERC largely accepted. LPSC, 117 FERC
    ¶ 61,203, P 75 (2006). The formula incorporated cost data
    from the operating companies’ annual Form 1 reports, which
    classify assets and expenses according to FERC’s Uniform
    System of Accounts. See 18 C.F.R. pt. 101. The bandwidth
    formula was keyed mostly to these FERC accounts. The
    formula included a variable for purchased-power expenses
    (PURP), which utilities incur when buying power on wholesale
    markets. PURP incorporated expenses recorded in FERC
    Account 555, which covers purchased-power expenses. See 
    id.
    pt. 101, acct. 555.
    The bandwidth remedy led to annual compliance
    proceedings. In April of each year, the operating companies
    would report production-cost data for the preceding year on
    Form 1. Using that data, Entergy would determine whether any
    of its operating companies fell outside the 11% bandwidth and
    report the results to FERC.
    4
    This petition concerns how the bandwidth formula
    accounts for deferred production costs. Utilities often must
    spread over many years their recovery of large, non-recurring
    costs. To do this, a company offsets those costs by creating a
    regulatory asset—a type of credit. The company then
    amortizes the asset in later years, creating debits chargeable to
    customers. Over time, FERC and Entergy have taken different
    positions on whether the bandwidth formula should recognize
    these production costs when an operating company incurs them
    or in later years as it amortizes the associated regulatory asset.
    Historically, the Entergy companies recorded regulatory
    assets and their related amortization expenses in two FERC
    accounts not referenced in the bandwidth formula—Account
    407.3 (Regulatory Debits) and Account 407.4 (Regulatory
    Credits). Entergy continued this practice in its first bandwidth
    filing, the 2007 filing concerning 2006 production data. In
    excluding regulatory assets and their amortization from the
    bandwidth calculation, Entergy effectively accounted for
    deferred production costs when they were incurred, rather than
    when the related amortization expenses were recorded. But
    FERC rejected this approach. It prohibited the companies from
    recording regulatory assets and amortization expenses in
    Accounts 407.3 and 407.4 when the assets and expenses could
    be traced to another account. See Entergy Servs., Inc., 130
    FERC ¶ 61,023, PP 261–65 (2010). And when the assets and
    expenses could be traced to accounts incorporated into the
    bandwidth formula, it ordered Entergy to treat amortization
    expenses as production costs for purposes of the formula. See
    LPSC, 132 FERC ¶ 61,253, P 34 (2010).
    Perhaps anticipating these rulings, Entergy revised its
    accounting for deferred purchased-power costs during the 2008
    bandwidth proceedings for 2007 cost data. Because the
    regulatory assets and related amortization expenses could be
    5
    traced to Account 555, Entergy began recording them there,
    rather than in Accounts 407.3 and 407.4. And because the
    bandwidth formula defined purchased-power expenses by
    reference to Account 555, this approach included amortization
    expenses in the bandwidth calculation. Entergy thus counted
    deferred purchased-power costs when the associated regulatory
    assets were amortized, rather than when the underlying costs
    actually were incurred.
    LPSC challenged this approach, and the parties reached a
    settlement. See Entergy Servs., Inc., 128 FERC ¶ 61,181
    (2009). It required Entergy to amend the bandwidth formula
    “starting with the 2009 Bandwidth Calculation (i.e., effective
    May 31, 2009) to provide that all purchased power costs will
    be included in the Bandwidth Calculation in the year the costs
    are incurred, regardless of whether they are deferred on the
    individual Operating Company’s books.” J.A. 1298.
    Pursuant to the settlement, Entergy proposed amending the
    definition of PURP. Under the amendment, PURP still would
    include most purchased-power expenses recorded in Account
    555, but it would “exclud[e] the effects, debits and credits,
    resulting from a regulatory decision that causes the deferral of
    the recovery of current year costs or the amortization of
    previously deferred costs.” J.A. 1327. FERC accepted the
    proposal and made the amendment effective May 31, 2009,
    before the 2009 bandwidth proceedings. See Entergy Servs.,
    Inc., 128 FERC ¶ 61,069, P 11 (2009). Under the amendment,
    the bandwidth formula again considered deferred purchased-
    power costs when the operating companies incurred them, not
    when the companies amortized the relevant regulatory assets.
    This petition concerns application of the amendment to the
    2009 and 2010 bandwidth proceedings, which involve
    production costs for 2008 and 2009. FERC reopened these
    6
    proceedings after it discovered accounting errors in the delayed
    bandwidth proceeding for 2005 production costs. There, an
    administrative law judge ruled that the operating companies
    had erroneously recorded certain regulatory assets and their
    associated amortization expenses in Accounts 407.3 and 407.4.
    LPSC, 157 FERC ¶ 63,018, P 101 (2016). One of these
    deferrals is at issue—a $56.3 million purchased-power cost that
    Entergy Louisiana, one of the operating companies, incurred in
    2005. To blunt its impact on ratepayers, LPSC had ordered the
    company to establish a regulatory asset and amortize it over
    four years. 
    Id.
     The ALJ ruled that Entergy Louisiana should
    have recorded the asset and its amortization in Account 555,
    and that Entergy had to revise the bandwidth calculation
    accordingly. 
    Id.
     PP 113–14. FERC agreed, but stressed that
    any corrections “should be limited to accounting adjustments
    that have been shown to have a bandwidth implication.” LPSC,
    163 FERC ¶ 61,116, PP 119–20 (2018) (Recalculation Order).
    Recognizing that the error implicated the bandwidth
    calculations for later years, FERC ordered Entergy Louisiana
    to refile its Form 1 report and ordered Entergy to adjust
    bandwidth payments for subsequent years “to ensure that
    legitimate production costs are properly accounted for on the
    FERC Form 1 reports and reflected in rates under the filed
    formula.” 
    Id.
     P 121.
    Entergy corrected the accounting and bandwidth
    calculations for the $56.3 million regulatory credit that Entergy
    Louisiana received in 2005 and the associated amortization
    expenses that it recorded in 2006 and 2007. But Entergy did
    not change its calculations for the amortization expenses
    recorded in 2008 and 2009. It reasoned that those expenses
    would not affect the bandwidth remedy under the 2009
    amendment, which expressly excluded amortization expenses
    from the calculation of purchased-power costs.
    7
    Entergy’s calculation locked a portion of Entergy
    Louisiana’s $56.3 million production cost out of the bandwidth
    remedy. When Entergy Louisiana incurred that cost in 2005,
    the bandwidth formula recognized deferred purchased-power
    costs only upon amortization, so the bandwidth calculation for
    2005 did not account for the costs. But for amortization
    expenses realized in 2008 and 2009, Entergy read the amended
    bandwidth formula to recognize deferred purchased-power
    costs only when they were actually incurred, so its revised
    calculations excluded those amortization expenses. As a result,
    Entergy Louisiana never received bandwidth credit for portions
    of the 2005 production cost that it amortized in 2008 and 2009.
    FERC agreed with Entergy that the 2009 amendment
    excluded these amortization expenses. LPSC, 167 FERC
    ¶ 61,186, PP 23–25 (2019) (Compliance Order). It reasoned
    that because the amended bandwidth formula was part of the
    filed rate, FERC could not include the amortization expenses
    in the bandwidth calculation. 
    Id.
     P 29. On rehearing, FERC
    rejected LPSC’s proposed interpretation of the 2009
    amendment and its fallback arguments for departing from the
    amendment. See LPSC, 169 FERC ¶ 61,247 (2019) (Rehearing
    Order).
    LPSC now seeks review of FERC’s ruling. We have
    jurisdiction to consider its petition under 16 U.S.C. § 825l(b).
    II
    We review FERC orders under the Administrative
    Procedure Act, which requires us to set aside decisions that are
    “arbitrary, capricious, an abuse of discretion, or otherwise not
    in accordance with law.” 5 U.S.C. § 706(2)(A); see Verso
    Corp. v. FERC, 
    898 F.3d 1
    , 7 (D.C. Cir. 2018). In a “technical
    area like electricity rate design,” we give FERC a significant
    degree of deference. FERC v. Elec. Power Supply Ass’n, 577
    
    8 U.S. 260
    , 292 (2016). We must accept FERC’s factual findings
    if they are “supported by substantial evidence.” 16 U.S.C.
    § 825l(b). We must also defer to FERC’s reasonable
    interpretation of tariffs, PSEG Energy Res. & Trade LLC v.
    FERC, 
    665 F.3d 203
    , 208 (D.C. Cir. 2011), and of its own prior
    orders, NSTAR Elec. & Gas. Corp. v. FERC, 
    481 F.3d 794
    , 799
    (D.C. Cir. 2007).
    The Federal Power Act requires electric utilities to charge
    “just and reasonable” rates. 16 U.S.C. § 824d(a). If FERC
    finds that a rate is unreasonable, it may establish a just and
    reasonable rate. Id. § 824e(a). Under this authority, FERC
    may reallocate production costs under the Entergy system
    agreement, including by ensuring compliance with the
    bandwidth remedy. LPSC II, 
    522 F.3d at 390
    –91. But because
    the bandwidth formula is part of a filed rate, FERC’s discretion
    is significantly limited. See LPSC v. FERC, 
    771 F.3d 903
    , 910
    (5th Cir. 2014) (LPSC III); LPSC v. FERC, 606 F. App’x 1, 4
    (D.C. Cir. 2015) (LPSC IV). Under the filed-rate doctrine, a
    utility “may not charge, or be forced by [FERC] to charge, a
    rate different from the one on file.” SFPP, L.P. v. FERC, 
    967 F.3d 788
    , 801–02 (D.C. Cir. 2020) (cleaned up); see also 16
    U.S.C. § 824d(c), (d) (requiring regulated utilities to
    prospectively file rates with FERC). As a corollary, FERC may
    adjust rates only prospectively. See id. § 824e(a). It cannot
    alter rates to retroactively correct for a past under-collection.
    Verso Corp., 898 F.3d at 10.
    A
    Because this case turns on the effect of the 2009
    amendment, we first decide what it means. We review FERC’s
    tariff interpretations with a “Chevron-like analysis.” PSEG,
    665 F.3d at 208 (cleaned up). Under that framework, we must
    9
    enforce unambiguous tariff language, but we defer to FERC’s
    reasonable interpretation of ambiguous text. Id.
    The 2009 amendment added the emphasized language to
    the definition of the PURP variable in the bandwidth formula:
    PURP = Purchased Power Expense recorded in FERC
    Account 555, but excluding payments made pursuant
    to Section 30.09(d) of this Service Schedule and
    excluding the effects, debits and credits, resulting
    from a regulatory decision that causes the deferral of
    the recovery of current year costs or the amortization
    of previously deferred costs.
    J.A. 1327 (emphasis added). The parties dispute whether the
    amendment applies to costs that are amortized after its adoption
    but rest on deferral decisions that predate it. FERC and Entergy
    contend that the amendment does so apply, while LPSC
    contends that it does not.
    We agree with FERC, for nothing in the amendment turns
    on the timing of a deferral decision. The amendment does not
    target deferral decisions as such, but rather their “effects.” So
    long as a purchased-power expense arises after the
    amendment’s effective date and results from a deferral
    decision, the amendment applies by its terms. And when a
    regulatory decision orders a company to amortize a previously
    incurred cost over several years, the ensuing amortizations
    plainly qualify as such “effects.”
    In response, LPSC highlights the phrase “debits and
    credits.” It argues that the amendment applies only if it would
    exclude both the debits and credits associated with a particular
    deferral decision. And so, LPSC concludes, the amendment
    does not exclude the “debits” of a preexisting deferral decision
    10
    because the related “credits” occurred at the time of the
    deferral—before the amendment had become effective.
    LPSC’s interpretation defies grammar. As nouns set off
    by commas, “debits and credits” are “explanatory
    equivalent[s]” of “effects,” the immediately preceding noun.
    Appositives, The Chicago Manual of Style § 6.28 (17th ed.
    2017); see R. Huddleston & G. Pullum, The Cambridge
    Grammar of the English Language 1357–58 (1st ed. 2002). In
    this context, “and” assumes its “distributive sense”—i.e., it
    means “A and B, jointly or severally.” Or and And, Garner’s
    Dictionary of Legal Usage (3d ed. 2011) (emphasis added); see
    also Huddleston & Pullum, supra, at 1281 (distributive sense
    is the “default”). The amendment treats debits and credits as
    distinct classes of excluded “effects.” After all, an effect is
    “[s]omething brought about by a cause or agent; a result.”
    Effect, American Heritage Dictionary (5th ed. 2018). And no
    fair reading of that term requires both a debit and a credit to
    constitute an effect resulting from a deferral decision. Instead,
    debits that arise from a deferral decision are “effects” of the
    decision regardless of whether the amendment also happens to
    cover a related credit.
    LPSC’s interpretation is also in tension with the rest of the
    amendment, which contemplates decisions that create only
    debits or only credits. Recall that the amendment excludes the
    effects of regulatory decisions that cause “the deferral of the
    recovery of current year costs or the amortization of previously
    deferred costs.” J.A. 1327 (emphasis added). A decision that
    requires a company to defer cost recovery causes only a credit,
    while a decision that permits the company to amortize
    previously deferred costs causes only debits. By listing these
    causes disjunctively, the amendment confirms its extension to
    regulatory decisions that cause only credits or only debits. In
    contrast, to apply only to decisions that cause both a credit and
    11
    a debit, the amendment would have had to cover regulatory
    decisions that cause “the deferral of the recovery of costs and
    the amortization of those costs.”
    LPSC next argues that other evidence, such as trial
    testimony and the settlement agreement that precipitated the
    amendment, show an intent to limit the amendment to later
    deferral decisions. According to LPSC, the settlement
    agreement is particularly important because it too is part of the
    filed rate. But because the amendment “unambiguously
    addresses the matter at issue,” its language controls. PSEG,
    665 F.3d at 208 (cleaned up). As for the settlement agreement,
    it simply required Entergy to amend the definition of the PURP
    variable in the future; the agreement itself did not alter the
    bandwidth formula, so it is not part of the filed rate.2
    In sum, the 2009 amendment is not limited to deferral
    decisions that postdate it. So long as an amortized purchased-
    power expense “result[s] from” a deferral decision, the
    amendment applies.
    B
    Our construction of the 2009 amendment largely resolves
    this appeal. As noted, the bandwidth formula is part of the filed
    rate. See LPSC III, 771 F.3d at 910; LPSC IV, 606 F. App’x at
    4. In the proceedings below, FERC found that the amendment
    was part of the bandwidth formula—and thus the filed rate—
    2
    To the extent LPSC contends that the settlement agreement
    should control over the amendment, we cannot consider its
    argument. The 60-day deadline to challenge FERC’s order
    approving the 2009 amendment has long expired. See 16 U.S.C.
    § 825l(b). Challenging the validity of that amendment would
    constitute an untimely collateral attack on the order approving it. See
    Pac. Gas & Elec. Co. v. FERC, 
    533 F.3d 820
    , 825 (D.C. Cir. 2008).
    12
    for the 2009 and 2010 proceedings. See Rehearing Order, 169
    FERC ¶ 61,247, P 29; Compliance Order, 167 FERC ¶ 61,186,
    P 25. This ruling, which no party disputed below, is consistent
    with FERC’s order accepting the amendment and ruling that it
    was effective for the 2009 bandwidth proceedings. Entergy
    Servs., Inc., 128 FERC ¶ 61,069, P 11.
    This finding obligated Entergy to exclude the disputed
    expenses from the bandwidth calculation. Even though the
    purchased-power expenses that Entergy Louisiana amortized
    in 2008 and 2009 were recorded in Account 555, they were also
    “effects” (or “debits”) “resulting from a regulatory decision
    that causes the deferral of the recovery of current year costs.”
    The 2009 amendment thus unambiguously excluded them from
    the bandwidth calculation. And FERC was bound to enforce
    the amendment as part of the filed rate, which it could not
    waive or retroactively amend. See NSTAR, 
    481 F.3d at 800
    .
    C
    LPSC raises three fallback arguments to support including
    the amortized expenses in the bandwidth formula despite the
    2009 amendment. They are unpersuasive.
    First, LPSC contends that FERC failed to follow its
    Recalculation Order, which required Entergy to adjust
    bandwidth payments after correcting the accounting errors
    uncovered in the 2005 bandwidth proceeding. 163 FERC
    ¶ 61,116, P 121. LPSC claims that this required Entergy to
    include amortization expenses in its subsequent bandwidth
    calculations for later years. But the Recalculation Order
    mandated corrections to ensure that Entergy Louisiana’s
    expense was “reflected in rates under the filed formula.” 
    Id.
    And beginning with bandwidth calculations for 2008 expenses,
    the “filed formula” included the 2009 amendment, which
    FERC was bound to apply. See NSTAR, 
    481 F.3d at 800
    .
    13
    Second, LPSC contends that applying the amendment to
    expenses that stem from the 2005 deferral decision would
    violate the prohibition on retroactive ratemaking. According
    to LPSC, the 2005 rate must govern because it was effective
    when LPSC ordered Entergy Louisiana to defer recovering the
    $56.3 million expense. By changing the applicable rate, LPSC
    reasons, FERC retroactively removed a benefit that Entergy
    Louisiana could reasonably expect to receive.
    LPSC misunderstands the rule against retroactive
    ratemaking. As discussed, the bandwidth remedy turns on
    production costs recorded in the preceding year. At most, the
    rule prohibited FERC from changing the rate for expenses that
    the companies had already recorded. See NSTAR, 
    481 F.3d at 800
    . For example, as the ALJ in these proceedings held, the
    rule prohibited applying the 2009 amendment to 2005
    production costs, which would have allowed Entergy
    Louisiana to fully account for its costs. LPSC, 157 FERC
    ¶ 63,018, P 111. Although LPSC’s 2005 deferral decision led
    to the amortization expenses at issue, Entergy Louisiana
    incurred those expenses in 2008 and 2009. And the rule against
    retroactive ratemaking does not protect a utility’s expectation
    that a rate will not change in the future. By seeking to change
    the rate that would otherwise govern production expenses
    recorded in 2008 and 2009, LPSC itself asks for an improper
    retroactive rate increase. As FERC correctly concluded, it
    cannot adjust current rates to make up for “over- or under-
    collection in prior periods.” Old Dominion Elec. Coop. v.
    FERC, 
    892 F.3d 1223
    , 1227 (D.C. Cir. 2018) (cleaned up).
    Alternatively, LPSC contends that the rule against
    retroactive ratemaking at least prohibited FERC from applying
    the 2009 amendment to expenses that the operating companies
    had incurred before FERC approved the amendment—that is,
    to production costs between January 2008 and May 2009.
    14
    Because LPSC did not raise this argument before FERC, we
    cannot consider it. See 16 U.S.C. § 825l(b). In its rehearing
    motion, LPSC argued only that the rule required the 2005 rate
    to govern all amortization expenses related to the deferral. It
    did not seek to apply the filed rate for the year in which
    expenses were amortized. Indeed, LPSC asserted to the ALJ
    that the amendment was “effective beginning with the 2009
    Bandwidth filing for the 2008 test year.” J.A. 90. And it told
    FERC that the settlement agreement “unambiguously applies
    to costs and deferrals going forward, beginning in the 2008 test
    year used for the 2009 Bandwidth Calculation.” J.A. 1335.
    LPSC cannot now pivot to new arguments that it previously
    conceded. See Cal. Dep’t of Water Res. v. FERC, 
    306 F.3d 1121
    , 1125 (D.C. Cir. 2002).3
    Third, LPSC contends that FERC arbitrarily declined to
    account for the amortized expenses under 16 U.S.C. § 825h,
    which allows FERC to “perform any and all acts . . . as it may
    find necessary or appropriate” to enforce the Federal Power
    Act. But the filed-rate doctrine “restrict[s] the remedies that
    FERC may order” under § 825h, Verso Corp., 898 F.3d at 10,
    by depriving it of “discretion to waive the operation of a filed
    rate or to retroactively change or adjust a rate for good cause or
    for any other equitable considerations,” Old Dominion, 892
    F.3d at 1230. And, to reiterate, the filed rate required FERC to
    exclude the disputed expenses from the bandwidth calculation.
    LPSC objects that the filed-rate doctrine does not apply
    “when judicial invalidation of Commission decisions has
    3
    Given our disposition, we need not consider FERC’s
    alternative ruling that LPSC consented to any retroactive rate.
    Rehearing Order, 169 FERC ¶ 61,247, P 30; see also NSTAR, 
    481 F.3d at 801
     (parties can “agree[] to make a rate effective
    retroactively” (cleaned up)).
    15
    resulted in retroactive changes in rates.” W. Deptford Energy,
    LLC v. FERC, 
    766 F.3d 10
    , 22 (D.C. Cir. 2014). But the
    exception LPSC invokes is narrow: FERC can retroactively
    correct for legal error only where, among other requirements,
    the parties “were aware in advance of the risk of litigation-
    induced change.” 
    Id. at 23
    . To create notice, there must be a
    close link between the claimed error and the change
    retroactively imposed on remand. Usually this means that the
    rate itself is subject to challenge, though in one case the
    challenge concerned the lawfulness of a rate in a settlement
    agreement that a party had accepted “in reliance on an unlawful
    FERC order.” Pub. Utils. Comm’n of Cal. v. FERC, 
    988 F.2d 154
    , 162–66 (D.C. Cir. 1993).
    Here, there was no notice that the rate set by the 2009
    amendment was subject to change. The validity of the
    amendment itself has never been questioned. Instead, LPSC
    offers an attenuated chain of causation between an unrelated
    legal error and approval of the amendment: This Court
    invalidated FERC’s decision to make the bandwidth remedy
    effective in 2006, which led FERC to extend the remedy to
    some costs incurred in 2005, which led an ALJ to discover that
    the operating companies had mistakenly recorded amortization
    expenses in non-bandwidth accounts. Had the arbitrary
    effective date not substantially delayed bandwidth proceedings
    for the 2005 production costs, LPSC continues, Entergy would
    have discovered the error in time to propose a different 2009
    amendment permitting all deferred-production costs to be
    recognized in the bandwidth calculation. Even assuming that
    LPSC’s inferences are true and that legal errors unrelated to
    underlying rates can trigger the exception, more than bare, but-
    for causation is required to overcome the “nearly impenetrable
    shield” against retroactive ratemaking. Old Dominion, 892
    F.3d at 1230. The litigation over the bandwidth’s start date
    could not have given notice that an ALJ would find accounting
    16
    errors significant enough to affect settlement negotiations over
    the 2009 amendment. The notice exception to the filed-rate
    doctrine does not apply. And because the filed-rate doctrine
    does apply, LPSC’s § 825h argument is without merit. See
    Verso Corp., 898 F.3d at 10.
    III
    For these reasons, we deny the petition for review.
    So ordered.