 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



Argued December 12, 2019            Decided August 11, 2020

                        No. 18-7177

                   KEITH ALLEN, ET AL.,
                       APPELLEES

                             v.

    DISTRICT OF COLUMBIA, A MUNICIPAL CORPORATION,
                     APPELLANT


                 Consolidated with 18-7178


        Appeals from the United States District Court
                for the District of Columbia
                    (No. 1:00-cv-00591)


    Richard S. Love, Senior Assistant Attorney General,
Office of the Attorney General for the District of Columbia,
argued the cause for appellant. With him on the briefs were
Karl A. Racine, Attorney General, Loren L. AliKhan, Solicitor
General, and Caroline S. Van Zile, Deputy Solicitor General.

     Michael J. Murali argued the cause for appellees. On the
brief was Ronald L. Drake.

   Before: SRINIVASAN, Chief Judge, and GRIFFITH and
KATSAS, Circuit Judges.
                               2
    Opinion for the Court filed by Circuit Judge KATSAS.

    KATSAS, Circuit Judge: In 2009, Congress enacted an
appropriations rider prohibiting the District of Columbia from
paying more than $4,000 in attorneys’ fees for any past
proceeding under the Individuals with Disabilities Education
Act (IDEA). These appeals present the question whether the
District must pay interest on amounts that exceed the payment
cap. They also present various challenges to the cap itself.

                                I

                               A

     The IDEA provides federal funds to States and the District
of Columbia to educate children with disabilities. 20 U.S.C.
§§ 1401(31), 1411(a)(1). In exchange, recipients must offer a
free appropriate public education to all eligible children. Id.
§ 1412(a)(1). Parents alleging that their child’s education falls
short of this standard are entitled to an administrative hearing,
id. § 1415(b)(6), (f), at which they have a “right to be
accompanied and advised by counsel,” id. § 1415(h)(1).
Parents aggrieved by a hearing officer’s decision may seek
review in a civil action. Id. § 1415(i)(2). Courts may “award
reasonable attorneys’ fees” to parents who prevail in the
administrative hearing or the lawsuit. Id. § 1415(i)(3)(B)(i);
see Moore v. District of Columbia, 907 F.2d 165, 167 (D.C.
Cir. 1990) (en banc).

     The District of Columbia has long struggled to comply
with the IDEA. By 1998, the District’s failures had “reached
crisis proportions.” Calloway v. District of Columbia, 216 F.3d
1, 3 (D.C. Cir. 2000) (cleaned up). This led to a flurry of
successful IDEA challenges, which in turn led to mounting
awards of attorneys’ fees. In 1998, the District was paying over
$10 million per year in IDEA attorneys’ fees, and Congress
                               3
grew concerned that these payments were diverting resources
from the D.C. public schools. See id. at 4.

     Congress responded by passing a series of appropriations
riders limiting the amount that the District could pay in IDEA
attorneys’ fees. For 1999, 2000, and 2001, Congress capped
the amount per proceeding that the District could pay out of
current appropriations. District of Columbia Appropriations
Act, 2001, Pub. L. No. 106-522, § 122(a), 114 Stat. 2440, 2464
(2000); District of Columbia Appropriations Act, 2000, Pub. L.
No. 106-113, § 129(a), 113 Stat. 1501, 1517 (1999); Omnibus
Consolidated and Emergency Supplemental Appropriations
Act, 1999, Pub. L. No. 105-277, § 130, 112 Stat. 2681, 2681-
138 (1998). For 2002, Congress provided that no current or
future appropriations for the District could be used to pay past
IDEA attorneys’ fees that exceeded caps in place when the
work was performed. District of Columbia Appropriations
Act, 2002, Pub. L. No. 107-96, § 140(a), 115 Stat. 923, 958
(2001) (2002 Act).

     For 2003 to 2008, Congress passed annual riders
prohibiting the District from paying more than $4,000 per
proceeding out of current appropriations for IDEA attorneys’
fees. Consolidated Appropriations Act, 2008, Pub. L. No. 110-
161, § 819(a), 121 Stat. 1844, 2040 (2007); Revised
Continuing Appropriations Resolution, 2007, Pub. L. No. 110-
5, § 101(a)(9), 121 Stat. 8, 9; Transportation, Treasury,
Housing and Urban Development, the Judiciary, the District of
Columbia, and Independent Agencies Appropriations Act,
2006, Pub. L. No. 109-115, § 122, 119 Stat. 2396, 2519 (2005);
District of Columbia Appropriations Act, 2005, Pub. L. No.
108-335, § 327(1), 118 Stat. 1322, 1344 (2004); Consolidated
Appropriations Act, 2004, Pub. L. No. 108-199, § 432(1), 118
Stat. 3, 141; Consolidated Appropriations Resolution, 2003,
Pub. L. No. 108-7, § 144(1), 117 Stat. 11, 131–32.
                               4
     For 2009, Congress passed a final appropriations rider.
Like the 2002 Act, it applied to current and future
appropriations. It provides that no funds appropriated for the
District “may be made available … to pay the fees of an
attorney who represents a party in or defends an IDEA
proceeding which was initiated prior to the date of the
enactment of this Act in an amount in excess of $4,000 for that
proceeding.” Omnibus Appropriations Act, 2009, Pub. L. No.
111-8, § 814(a)(1), 123 Stat. 524, 697 (2009 Act).

                               B

    In these eleven consolidated cases, the plaintiffs are
hundreds of parents who prevailed against the District in IDEA
proceedings initiated before the 2009 Act was enacted. They
were awarded attorneys’ fees at various times between 2001
and 2009. The District has refused to pay fees that exceed the
current cap of $4,000 per proceeding.

     In 2015, the plaintiffs moved to compel the District to pay
the balance of their attorneys’ fees with interest. The district
court held that the 2009 Act applies to all the plaintiffs’ IDEA
proceedings. See Allen v. District of Columbia, 128 F. Supp.
3d 74, 81–82 (D.D.C. 2015) (Allen I). The court further held
that the payment cap does not violate the separation of powers,
the Takings Clause, or the Equal Protection Clause. Id. at 83–
84. The court referred the matter to a magistrate judge to
determine the amounts due in each of the cases. Id. at 85.

     The magistrate judge separately calculated how much the
District owed and how much it could lawfully pay. He
determined that the District owed a total of about $3.7 million
in fee awards, which had accumulated over $1.3 million in
interest. Applying the payment cap, the magistrate judge
recommended that the District be required to pay about
                                 5
$514,000 in fee awards and costs. He did not recommend that
the District be required to pay any interest.

     Both sides filed objections to the magistrate judge’s report
and recommendation. The plaintiffs objected to its failure to
include interest; the District did not mention that issue. While
the dispute was pending before the district court, the District
paid the plaintiffs some $427,000, which it characterized as
including all undisputed fees plus interest on those fees. The
district court prodded the parties to clarify their exact positions
on and calculation of interest. The plaintiffs then asserted that
the District should be required to pay interest on the full
amount of fee awards, not just on amounts up to the payment
cap. The District responded that it could not be compelled to
pay interest on debts that it was legally forbidden to pay off.

     The district court agreed with the plaintiffs. It held that the
District’s position was both forfeited and meritless. Allen v.
District of Columbia, 263 F. Supp. 3d 14, 32–33 (D.D.C. 2017)
(Allen II). After modifying the magistrate judge’s calculations,
the court ordered the District to pay some $220,000 in further
outstanding fee awards, as limited by the payment cap, and
about $1.4 million in interest accumulated on the entire amount
of all unpaid awards. See id. at 46.

                                 II

    The District raises only one contention on appeal: that it
cannot be compelled to pay interest on fee awards that
Congress has prohibited it from paying.

                                 A

    The district court held that the District forfeited this
argument by not raising it under the court’s Local Rule 72.3(b).
                                6
That rule requires a party to file written objections to a
magistrate judge’s report and recommendation within 14 days.

     The District did not forfeit the interest issue. Because the
magistrate judge did not recommend requiring it to pay any
interest, much less interest on the full fee awards, the District
had no reason to object on that basis. Nor was the question
otherwise fairly teed up. To the contrary, before referring the
matter to the magistrate judge, the district court ruled that the
District “must pay plaintiffs $4,000—less any amount already
paid—plus interest, for each action.” J.A. 216. This
formulation at least suggested that interest would be due only
on amounts up to the $4,000 cap. The court also instructed the
magistrate judge “to calculate the amount of interest due from
the date of judgment until October 1, 2015, so that any further
statutory change authorizing additional payments in the
outstanding judgments will be readily actionable.” Allen I, 128
F. Supp. 3d at 85. This further suggested that the District would
pay interest on the full awards only if Congress lifted the fee
cap. In turn, the magistrate judge separately determined the
“amount of fees and costs due now pursuant to the $4,000 fee
cap”—with no provision for interest—and the “amount of the
remaining judgment with interest” calculated on the entire fee
awards. J.A. 268 (cleaned up). Finally, the magistrate judge’s
proposed orders would have required the District to pay only
the outstanding below-cap fees, plus costs, with no interest.

     The District did not need to object to something that the
magistrate judge had not recommended. Neither the court’s
instructions to the magistrate judge nor the magistrate judge’s
report and recommendation fairly warned that the District
might be required to pay interest on the full fee awards. And
as soon as the district court raised that possibility, the District
promptly objected, thus preserving the issue.
                                7
                                B

    On the merits, the District contends that the 2009 fee cap
prohibits it from paying interest on the full judgment amounts.
We review this question of law de novo. See Conservation
Force v. Salazar, 699 F.3d 538, 542 (D.C. Cir. 2012).

     The plaintiffs’ argument is straightforward: By its terms,
the 2009 Act prohibits the use of any appropriated funds to pay
more than $4,000 per IDEA proceeding for “the fees of an
attorney.” Pub. L. No. 111-8, § 814(a)(1), 123 Stat. at 697. But
without exception, another statute provides that “[i]nterest shall
be allowed on any money judgment in a civil case recovered in
a district court.” 28 U.S.C. § 1961(a). And “any money
judgment” includes an award of attorneys’ fees. Akinseye v.
District of Columbia, 339 F.3d 970, 972 (D.C. Cir. 2003).
Thus, the 2009 Act prohibits payment of certain fees, yet
section 1961(a) nonetheless requires payment of interest on
those fees. The argument is beguilingly simple, but it
overlooks an important background principle.

     The Supreme Court has explained that, “where a common-
law principle is well established, … courts may take it as a
given that Congress has legislated with an expectation that the
principle will apply except when a statutory purpose to the
contrary is evident.” Astoria Fed. Sav. & Loan Ass’n v.
Solimino, 501 U.S. 104, 108 (1991) (cleaned up). “In order to
abrogate a common-law principle, the statute must ‘speak
directly’ to the question addressed by the common law.”
United States v. Texas, 507 U.S. 529, 534 (1993) (quoting
Mobil Oil Corp. v. Higginbotham, 436 U.S. 618, 625 (1978)).
The Court repeatedly has applied this principle to narrow the
scope of seemingly unbounded statutes. For example, although
the Patent Act provides a patentee with the textually
unqualified right to exclude others from his invention, the
                                8
Supreme Court has recognized an “unwritten limit”—that the
patentee loses this right upon sale of the invention—based on
the common law’s “antipathy toward restraints on alienation.”
Impression Prods., Inc. v. Lexmark Int’l, 137 S. Ct. 1523, 1531,
1536 (2017). In construing statutory causes of action, the Court
has invoked common-law principles to impose causation
requirements that do not appear in the governing text. See, e.g.,
Comcast Corp. v. NAACP, 140 S. Ct. 1009, 1014–17 (2020)
(42 U.S.C. § 1981); Holmes v. SIPC, 503 U.S. 258, 265–68
(1992) (civil RICO); Associated Gen. Contractors of CA v.
California State Council of Carpenters, 459 U.S. 519, 529–35
(1983) (Clayton Act). And although criminal statutes often
seem to impose strict liability, the Court, invoking background
principles, does not “construe mere omission from a criminal
enactment of any mention of criminal intent as dispensing with
it.” Morissette v. United States, 342 U.S. 246, 250 (1952).

     This case implicates another well-established common-law
principle: If the law makes a debt unpayable, then interest on the
debt is also unpayable. This rule flows from the meaning of
interest, which is “given on money demands as damages for
delay in payment.” Redfield v. Ystalyfera Iron Co., 110 U.S.
174, 176 (1884); see also Library of Congress v. Shaw, 478
U.S. 310, 322 (1986) (interest is “designed to compensate for
the belated receipt of money”); Shoemaker v. United States,
147 U.S. 282, 321 (1893) (“Interest accrues … in the nature of
damages, by reason of the failure of the debtor to pay the
principal when due.”). When Congress has prohibited a
monetary payment, its delayed receipt is not wrongful; instead,
it is obligatory. And a party cannot fairly be made to pay
“damages” for doing what the law requires.

     This principle is as old as the Republic. As far back as
1789, the Supreme Court held that an American debtor owed
no interest to a British creditor for the time between September
                               9
1775 and March 1783, when the Continental Congress had
made it illegal to “make any remittances” to British subjects.
Hoare v. Allen, 2 U.S. (2 Dall.) 102, 103 (1789). The Court
explained that “[w]here a person is prevented by law, from
paying the principal, he shall not be compelled to pay interest
during the prohibition.” Id. This followed from the nature of
interest: “Interest is paid for the use or forbearance of money.
But in the case before us, there could be no forbearance;
because the plaintiff could not enforce the payment of the
principal; nor could the defendants pay [the plaintiff],
consistent with law ….” Id. The Court later applied the same
rule in Brown v. Hiatts, 82 U.S. (15 Wall.) 177 (1872), which
arose from legislation prohibiting certain payments during the
Civil War. The Court gave the same explanation: “Interest is
the compensation allowed by law, or fixed by the parties, for
the use or forbearance of money, or as damages for its
detention, and it would be manifestly unjust to exact such
compensation, or damages, when the payment of the principal
debt was interdicted.” Id. at 185. The Court stated that “[a]s a
general rule it may be safely laid down that wherever the law
prohibits the payment of the principal, interest during the
existence of the prohibition is not demandable.” Id. at 186
(cleaned up).

     We have no basis to conclude that section 1961(a)
abrogated this background rule. Judgments are normally
enforceable, so a statute providing for interest on judgments
does not “speak directly,” United States v. Texas, 507 U.S. at
534, to specific cases where Congress has prohibited their
payment. To be sure, section 1961(a) provides for interest on
“any” district-court judgment. But “generic terms like ‘any’ or
‘every’ do not rebut” settled background rules. Kiobel v. Royal
Dutch Petroleum Co., 569 U.S. 108, 118 (2013). For example,
given the background presumption against extraterritoriality, a
statute covering “any civil action” does not sweep in civil
                               10
actions based on acts committed abroad. See id. And given the
background presumption that a crime requires bad intent, a
statute reaching “any communication containing any threat …
to injure” does not sweep in threats made through negligence.
Elonis v. United States, 135 S. Ct. 2001, 2009–11 (2015).
Likewise, a statute providing for interest on “any” judgment
does not abrogate the background rule governing interest on
debts for which Congress has prohibited payment.

     The specific context of the 2009 Act reinforces this
conclusion. Recall that by 1998 the District was paying over
$10 million annually to IDEA attorneys, which prompted
Congress to adopt eleven different appropriations riders
culminating in the 2009 Act. The obvious purpose of these
riders was to limit the amount that the District pays to IDEA
attorneys. But requiring payment of interest on fee awards that
the District was prohibited from paying would have precisely
the opposite effect. Over time, that would force the District to
pay more to IDEA attorneys than it would have had to pay
without the cap. Indeed, the plaintiffs’ position would convert
a permanent payment cap imposed on the District into a
permanent annuity for IDEA attorneys. We should not “lightly
conclude” that Congress enacted such a “self-defeating
statute.” Quarles v. United States, 139 S. Ct. 1872, 1879
(2019); see also A. Scalia & B. Garner, Reading Law: The
Interpretation of Legal Texts 63 (2012). Of course, we must be
careful in invoking statutory purposes to depart from seemingly
clear statutory text. But here, a relevant background rule has
operated for centuries, and we need only read the governing
statute in light of that rule.

     The district court and the plaintiffs offer various responses
to the Brown line of cases, but none is persuasive. The district
court asserted that here, unlike in those cases, payment of the
principal “was never suspended.” Allen II, 263 F. Supp. 3d at
                              11
33. That is incorrect; Congress has prohibited payment of fee
awards over $4,000 in individual IDEA proceedings for over
two decades. For their part, the plaintiffs contend that Brown
is distinguishable because these cases do not involve a war.
But Brown, like Hoare before it, turned squarely on the nature
of interest, not the nature of war. See 82 U.S. at 186 (“As a
general rule it may be safely laid down that wherever the law
prohibits the payment of the principal, interest during the
existence of the prohibition is not demandable.”). Finally, the
plaintiffs contend that section 1961(a) has superseded the
Brown line of cases. They are mistaken. As explained above,
these cases establish a firm background common-law rule,
which section 1961(a) does not speak clearly to abrogate.

    For these reasons, we hold that the District cannot be
compelled to pay interest on the portion of fee awards that it
has been legally prohibited from paying off.

                              III

     On cross-appeal, the plaintiffs argue that the 2009 fee cap
does not apply at all to most of the fee awards at issue. They
further raise separation of powers and takings challenges to the
cap. And they contend that the cap breaches the District’s duty
of good faith and fair dealing. We review these legal
arguments de novo. See Conservation Force, 699 F.3d at 542.

                               A

     We begin with the plaintiffs’ statutory arguments. First,
the plaintiffs invoke the presumption against statutory
retroactivity, see Landgraf v. USI Film Prods., 511 U.S. 244
(1994), to contend that the 2009 Act should not be applied to
their fee awards. But the statute does speak clearly to its own
temporal scope; by its terms, it applies to fees in IDEA
                                12
proceedings “initiated prior to the date of the enactment of this
Act.” Pub. L. No. 111-8, § 814(a)(1), 123 Stat. at 697.

     Next, the plaintiffs argue that the 2009 Act, which is an
appropriations statute, should not be construed to modify
substantive law. Insofar as the plaintiffs suggest that the
funding restrictions in the 2009 Act do not govern future
appropriations, they again overlook clear statutory text. By its
terms, the 2009 Act restricts use of “the funds contained in this
Act or in any other Act making appropriations for the
government of the District of Columbia for fiscal year 2009 or
any succeeding fiscal year.” Pub. L. No. 111-8, § 814(a), 123
Stat. at 697. Moreover, we have held that the 2002 Act, which
was similarly worded in this respect, applied to current and
future appropriations. See Whatley v. District of Columbia, 447
F.3d 814, 820 (D.C. Cir. 2006).

     The plaintiffs briefly suggest that the payment cap applies
only to federally appropriated funds and thus does not prohibit
use of the District’s other revenue sources to pay off the fee
awards. But the plaintiffs fail to identify any such sources or
otherwise to develop this theory beyond bald assertion. We do
not consider arguments raised in such skeletal form. Schneider
v. Kissinger, 412 F.3d 190, 200 n.1 (D.C. Cir. 2005). In any
event, in construing the 2002 Act, we took it for granted that a
prohibition on the District’s ability to spend federally
appropriated funds amounts to a blanket spending prohibition.
See Whatley, 447 F.3d at 819–20 (“the District is never to pay
fees for work done or fees requested in the relevant years”).

                                B

     We next consider the plaintiffs’ constitutional challenges
to the fee cap. First, the plaintiffs contend that the cap violates
the separation of powers by commanding the courts to reopen
final judgments, which is unconstitutional under Plaut v.
                               13
Spendthrift Farm, Inc., 514 U.S. 211 (1995). But the 2009 Act
does no such thing. Instead, it limits the future use of funds to
“pay” for attorneys’ fees in IDEA proceedings initiated prior to
its enactment. Pub. L. No. 111-8, § 814(a)(1), 123 Stat. at 697.
As we explained in construing the 1999 appropriations rider,
such a statute does not prevent the entry of future judgments.
See Calloway, 216 F.3d at 18–19. Nor does it retroactively
“reverse” past final judgments. See Plaut, 514 U.S. at 225.

     The plaintiffs further contend that the 2009 Act violates
the separation of powers by purporting to bind future
Congresses. The 2009 Act does continue to govern current and
future appropriations, but nothing in it prevents (or could
prevent) a future Congress from lifting its payment restrictions.
As we explained in Whatley, barring “payment in subsequent
fiscal years” is different from purporting to bar subsequent
statutory amendments. 447 F.3d at 821–22 (cleaned up).

      Finally, the plaintiffs argue that the fee cap violates the
Takings Clause of the Fifth Amendment, which prohibits
“private property” from being “taken for public use, without
just compensation.” But the 2009 Act did not effect a per se
taking, because it neither appropriated nor physically invaded
the plaintiffs’ fee awards. See Lingle v. Chevron U.S.A. Inc.,
544 U.S. 528, 537 (2005). Nor does the 2009 Act effect a
regulatory taking, which turns on the economic impact of the
challenged regulation, its interference with reasonable
investment-backed expectations, and its character. Penn Cent.
Transp. Co. v. New York City, 438 U.S. 104, 124 (1978). Here,
the economic impact of the fee cap is limited, as the plaintiffs
still may recover attorneys’ fees of $4,000 per proceeding plus
costs and interest on that amount. Moreover, the fee cap does
not interfere with any reasonable expectations, for each of the
awards at issue was entered at a time when Congress had
already limited the District’s ability to pay IDEA fee awards.
                               14
Far from upsetting the status quo, the 2009 Act merely carried
it forward. Finally, the fee cap involves the allocation of scarce
public resources—a kind of government action unlikely to
amount to a taking.

                                C

     The plaintiffs argue that the District breached a duty of
good faith and fair dealing when it lobbied for the fee cap while
negotiating consent judgments in two of the cases under
review. The plaintiffs failed to raise this argument before the
district court, so we do not consider it. See Keepseagle v.
Perdue, 856 F.3d 1039, 1053 (D.C. Cir. 2017).

                               IV

     For these reasons, we reverse the district court’s judgment
requiring payment of interest on above-cap fees, affirm the
district court’s judgment in all other respects, and remand for
further proceedings consistent with this opinion.

                                                     So ordered.
