                          PUBLISHED

UNITED STATES COURT OF APPEALS
                FOR THE FOURTH CIRCUIT


DONALD F. RIESETT,                     
                Plaintiff-Appellant,
                 v.
W.B. DONER & COMPANY; DONER                  No. 01-2307
INTERNATIONAL, LIMITED, d/b/a Doner
& Company, Limited, d/b/a Doner
Cardwell Hawkins,
              Defendants-Appellees.
                                       
DONALD F. RIESETT,                     
                 Plaintiff-Appellee,
                 v.
W.B. DONER & COMPANY; DONER                  No. 01-2339
INTERNATIONAL, LIMITED, d/b/a Doner
& Company, Limited, d/b/a Doner
Cardwell Hawkins,
             Defendants-Appellants.
                                       
          Appeals from the United States District Court
           for the District of Maryland, at Baltimore.
           Frederic N. Smalkin, Chief District Judge.
                         (CA-00-2026-S)

                      Argued: May 8, 2002

                      Decided: June 6, 2002

      Before WILKINSON, Chief Judge, and WILKINS and
                  LUTTIG, Circuit Judges.
2                RIESETT v. W.B. DONER & COMPANY
Affirmed in part and vacated and remanded in part by published opin-
ion. Judge Luttig wrote the opinion, in which Chief Judge Wilkinson
and Wilkins joined.


                            COUNSEL

ARGUED: James A. Dunbar, VENABLE, BAETJER & HOWARD,
L.L.P., Towson, Maryland, for Appellant. Robert Michael Jackson,
HONIGMAN, MILLER, SCHWARTZ & COHN, L.L.P., Detroit,
Michigan, for Appellees. ON BRIEF: Kathleen E. Wherthey, VEN-
ABLE, BAETJER & HOWARD, L.L.P., Rockville, Maryland, for
Appellant. Robert J. Muchnick, HONIGMAN, MILLER,
SCHWARTZ & COHN, L.L.P., Detroit, Michigan; Abbey G. Hairs-
ton, SEYFARTH SHAW, Baltimore, Maryland, for Appellees.


                             OPINION

LUTTIG, Circuit Judge:

   W.B. Doner & Co. is an S corporation incorporated under the laws
of Michigan. Donald Riesett, a citizen of Maryland, worked for Doner
until February, 2000. While employed at Doner, Riesett held Doner
stock, pursuant to a Shareholder Agreement, which provided:

    [u]pon the termination of a Shareholder’s employment with
    the Company for any reason . . . Company will buy, and
    such shareholder . . . will sell, all of such Shareholder’s
    Shares for the price established under Section 4.1 or .2
    below, as applicable, with settlement to be made in accor-
    dance with Section 5 below.

J.A. 66. Doner did not redeem the stock after Riesett’s termination of
employment, and on June 30, 2000 Riesett filed a twelve-count com-
plaint against Doner, under the diversity jurisdiction of 28 U.S.C.
§ 1332, alleging breach of contract and violations of state law. J.A.
11-79. On February 14, 2001 the parties entered into a Settlement
Agreement that required Doner to pay Riesett several hundred thou-
                 RIESETT v. W.B. DONER & COMPANY                      3
sand dollars in damages (some of it payable immediately, the remain-
der payable in 120 monthly installments). J.A. 340-41. Doner also
agreed to redeem Riesett’s stock for $142,257.70 (subject to adjust-
ments), most of it payable in four yearly installments, each due on
May 31st. In the event of default by Doner, the Settlement Agreement
provides:

    Riesett shall provide Doner with written notice of such
    untimely payment. If Doner fails to make any payment
    required under this Agreement with [sic] five (5) business
    days of receipt of notice from Riesett, then all further
    amounts due under this Agreement or those agreements
    shall become immediately due and payable.

J.A. 342. Doner further agreed to provide Riesett’s accountant with
information "reasonably necessary to form an opinion as to the proper
valuation of Riesett’s stock in Doner." J.A. 341.

   Despite the settlement agreement, further litigation ensued. Riesett
filed an amended complaint in the district court, post-settlement, with
two new counts. Count XIII sought an order requiring Doner to pro-
duce certain documents that Riesett believed to be relevant to the val-
uation of Riesett’s Doner stock. J.A. 194-95. In Count XIV, Riesett
asserted his right, as a shareholder of Doner, to a distribution to
defray taxes on his income, which the other shareholders of Doner
received in January 2001. Finally, Riesett filed a motion to enforce
the settlement agreement by accelerating all the stock redemption
installment payments because the scheduled May 31, 2001 payment
arrived late.

   The district court granted summary judgment to Riesett on Count
XIII, J.A. 437-41, but granted summary judgment to Doner on Count
XIV, J.A. 441-45. Finally, the district court granted in part and denied
in part Riesett’s motion to enforce the settlement agreement. The dis-
trict court refused to accelerate the remaining stock redemption
installment payments, as Riesett requested, but instead ordered Doner
to pay Riesett interest at the prime rate for the delay in the payment
that should have arrived on May 31, 2001.
4                 RIESETT v. W.B. DONER & COMPANY
   Because the district court entered a final judgment on all these
claims pursuant to Fed. R. Civ. P. 54(b), we have jurisdiction over the
parties’ cross-appeals.

                                   I.

   We begin with Count XIV of Riesett’s amended complaint, where
Riesett seeks enforcement of his rights as a shareholder of Doner.
Doner is an S corporation, and its shareholders receive distributions,
at the beginning of each calendar year, to help them defray taxes on
the income allocated to them by Doner and reflected on their K-1
statements. In January of 2001, Doner gave each of its shareholders
a check for 43.5% of the income allocated on their form K-1 to defray
tax liabilities.

   Doner refused to give Riesett such a disbursement because Doner
claimed he was no longer a shareholder. Riesett still received his form
K-1 on March 2, 2001, which allocated nearly $800,000 in taxable
income to Riesett for Doner’s fiscal year ending on February 29,
2000, and faced a significant personal tax liability on that income,
without receiving the customary distribution from Doner to defray
this cost. Riesett claims he is still a Doner shareholder notwithstand-
ing his termination of employment, and claims that Doner violated
Mich. Comp. Laws Ann. § 450.1301(3)1 by withholding the distribu-
tion and treating him differently than other shareholders in the same
class.

   The district court concluded that Riesett’s shareholder status termi-
nated when his employment ended in February, 2000, even though,
by March 2, 2001, Riesett had not yet surrendered his stock certifi-
cates to Doner and had not received full payment for the stock. J.A.
444. The district court reasoned that "[t]he unconditional requirement
that Riesett transfer his shares to Doner upon termination of his
employment clearly indicates that the parties contemplated that Rie-
    1
    "[E]ach share shall be equal to every other share of the same class."
Mich. Comp. Laws Ann. § 450.1301(3). See also Polish American Pub-
lishing Co. v. Wojcik, 273 N.W. 771, 774 (Mich. 1937) ("All persons
who own shares of stock in a corporation at the time a dividend is
declared thereon are entitled to share in the dividend.").
                  RIESETT v. W.B. DONER & COMPANY                       5
sett would be a shareholder only while employed for the corporation."2
J.A. 444.

   We do not agree with the district court that Doner was entitled to
summary judgment on the ground that Riesett was no longer a share-
holder. The Shareholder agreement does not state that title to an
employee’s stock immediately passes to Doner upon that employee’s
termination; rather, it merely obligates the employee to sell and the
company to buy all of the shares the employee owns at some point
in time after termination of employment. The text of the Shareholder
agreement bears repeating:

      [u]pon the termination of a Shareholder’s employment with
      the Company for any reason . . . Company will buy, and
      such shareholder . . . will sell, all of such Shareholder’s
      Shares for the price established under Section 4.1 or .2
      below, as applicable, with settlement to be made in accor-
      dance with Section 5 below.

J.A. 66 (emphasis added). Section 5 provides when the "closing" or
such a sale or purchase of stock would take place:

      The Closing Date will be . . . (b) if the purchase is made
      other than under clause (a) above, the later of (1) 90 days
      after the date of the event giving rise to the purchase of
      Shares from the Shareholder and (2) 30 days after the finan-
      cial statements needed to determine the Book Value of such
      Shareholder’s Shares have been completed.

J.A. 69. A reasonable jury could certainly conclude that, under the
Shareholder Agreement, a terminated employee retains his rights as
  2
   The district court further relied on Jenkins v. Haworth, Inc., 572 F.
Supp. 591, 601 (W.D. Mich. 1983) (holding that a terminated employee
was no longer a shareholder, even though he had not yet surrendered his
stock certificates nor received payment for them, because of a Buy/Sell
agreement in the Shareholder contract similar to the one in this case).
Jenkins is not mandatory authority. It is a federal district court opinion
predicting what the Michigan state supreme court would do, not an
authoritative interpretation from a state court.
6                   RIESETT v. W.B. DONER & COMPANY
a shareholder until "closing," and that Riesett therefore retained his
rights as a shareholder after termination. Indeed, it is even possible,
although we need not reach the issue, that the shareholder agreement
unambiguously means that an employee does not automatically lose
his shareholder status upon termination of employment. The agree-
ment did not require Riesett to sell his stock immediately (and he did
not), nor did it automatically strip Riesett of his status or rights as a
shareholder upon termination. The agreement easily could have been
drafted with provisions that would have eliminated any ambiguities
and clearly stated that employees immediately lose their rights as
shareholders upon termination of employment.3 It was not so drafted,
and the district court erred in granting summary judgment on this
ground.

   We nevertheless affirm the district court’s grant of summary judg-
ment to Doner on Count XIV because, regardless of whether Riesett
remained a shareholder of Doner, he released this claim through the
Settlement Agreement he signed on February 14, 2001. Riesett agreed
to release Doner from:

        any claims for any other relief which have or could have
        arisen out of the employment relationship, or any other
        occurrence whatsoever to the date of execution of the agree-
        ment, whether presently asserted or otherwise, whether
        known or unknown, whether suspected or unsuspected.

J.A. 343 (emphasis added). Riesett’s claim accrued in January of
2001, when the distribution to the shareholders occurred. See Mich.
Comp. Laws Ann. § 600.5827 ("[a] claim accrues at the time the
wrong upon which the claim is based was done regardless of the time
when the damage results"). The settlement agreement was signed
after that and therefore released Doner from liability for not making
a distribution to Riesett. Riesett’s argument that the claim accrued on
    3
   We are not the first court to make this observation regarding buy-sell
agreements in closely-held corporations. See Stephenson v. Drever, 947
P.2d 1301, 1305 ("[T]he parties have the power to agree that a share-
holder loses his status as a shareholder upon some event other than actual
transfer of shares to another.") (citing Stephenson v. Drever, 57 Cal.
Rptr. 2d. 662, 664 (Cal. Ct. App. 1997)).
                 RIESETT v. W.B. DONER & COMPANY                      7
March 2, 2001 is without merit. Although Riesett received his form
K-1 on that date, the allegedly wrongful distribution to Doner’s share-
holders, with Riesett excluded, occurred in January. Perhaps, Riesett
learned of his claim on March 2, 2001, but the release covers claims
"known or unknown" that existed on February 14. Accordingly, the
district court’s grant of summary judgment to Doner on Count XIV
is affirmed.

                                  II.

   We next address Count XIII. After the parties executed the Settle-
ment Agreement, Riesett’s accountant demanded the following docu-
ments from Doner: Doner’s annual audited financial statements and
federal tax returns, a complete analysis of stockholder equity transac-
tions that occurred from March 1, 1981 through February 28, 2001,
and any analysis of shareholder retained earnings for the period 1982
through 2001. Doner refused to turn them over, and Riesett sued. The
district court granted Riesett’s motion for summary judgment on
Count XIII, concluding that Riesett’s accountant was entitled to these
documents pursuant to the Settlement Agreement, which provides:

    Riesett’s accountant shall have the right to obtain from
    Doner’s accountants all information reasonably necessary
    to form an opinion as to the proper valuation of Riesett’s
    stock in Doner. . . . Upon receipt of the requested informa-
    tion, [Riesett’s accountant] will have the right to obtain from
    Doner’s accountants additional information necessary and
    appropriate to form an opinion as to the proper valuation
    of Riesett’s stock in Doner.

J.A. 341 (emphasis added).

   Doner deems this request unreasonable and unnecessary to calcu-
late "book value" as defined in the Shareholder Agreement, and fur-
ther contends that the only documents necessary to calculate the
"book value" as defined in the Shareholder Agreement are the balance
sheet and schedule of combined book value per share of common
stock for the end of the fiscal year 1999. Doner’s arguments are
beside the point because they disregard the language of the Settlement
Agreement. As the district court correctly observed, the Settlement
8                 RIESETT v. W.B. DONER & COMPANY
Agreement does not require that the information requested by Rie-
sett’s accountant be relevant to "book value" as defined in the Share-
holder Agreement. J.A. 438. Rather, the only limitation on the
information available to Riesett’s accountant is that it be "reasonably
necessary to form an opinion" as to the "proper valuation" of Rie-
sett’s stock. J.A. 341 (emphasis added). Nowhere does the Settlement
Agreement define "proper valuation" as "book value" under the
Shareholder Agreement; indeed, the Agreement does not provide any
definition of "proper valuation." Because the parties used such an
imprecise term, we conclude, as did the district court, that the Settle-
ment Agreement entitles Riesett to make an independent assessment
of the value of his stock, and that the requested documents are "rea-
sonably necessary" to that end. The district court’s grant of summary
judgment to Riesett on this issue is affirmed.

                                   III.

   Finally, we turn to Riesett’s contention that the district court should
have accelerated Doner’s payments because of the late arrival of an
installment due on May 31, 2001. The Settlement Agreement pro-
vides that, in the event of default by Doner,

     Riesett shall provide Doner with written notice of such
     untimely payment. If Doner fails to make any payment
     required under this Agreement with [sic] five (5) business
     days of receipt of notice from Riesett, then all further
     amounts due under this Agreement or those agreements
     shall become immediately due and payable.

J.A. 342 (emphasis added).

   Doner had agreed to redeem Riesett’s stock for $142,257.70 (sub-
ject to adjustments), with most of that sum payable in four yearly
installments, each due on May 31. When Doner failed to make pay-
ment on May 31, 2001, Riesett sent a three-line notice of default
addressed to H. Barry Levine (Vice Chairman of Doner) by certified
mail. A return receipt shows an indecipherable signature (but not
Levine’s) and a date of delivery of June 1, 2001. J.A. 566. Doner
claims that Levine "does not recall" receiving the letter of May 31,
but that when Levine learned of the default on July 27, 2001, he
                 RIESETT v. W.B. DONER & COMPANY                      9
promptly cured the default by mailing a payment of $26,673.36 to
Riesett on July 31, 2001. J.A. 566. (This was the amount due Riesett
on May 31, but without interest for Doner’s two-month delay.)

   The district court found that even though Riesett complied with the
notice requirement, it would be "unreasonable and unconscionable" to
impose upon Doner the "harsh sanction" of accelerating the entire
amount due Riesett for the redemption of his stock. J.A. 568. Instead,
the district court ordered Doner to pay interest at the prime rate for
the delay in payment from May 31, 2001 to August 2, 2001, when the
check of $26,673.36 was received by Riesett. Id. We must address
two issues: first, whether the conditions for enforcing the acceleration
clause were satisfied, and second, if they were, whether we should
nevertheless deny enforcement of that contractual provision.

                                  A.

   Under the Settlement Agreement, only two conditions must be met
for Riesett to invoke the acceleration clause. First, Riesett must "pro-
vide Doner with written notice" of the untimely payment. Second,
Doner must "fail[ ] to make" the delinquent payment "with [sic] five
(5) business days of receipt of notice from Riesett." We find it diffi-
cult to credit Doner’s argument that Riesett failed to "provide Doner
with written notice," (emphasis added), as did the district court, which
found Doner’s arguments on this point to be "specious." J.A. 567.
Someone at Doner signed the certified mail receipt, and although Rie-
sett addressed the notice to Mr. Levine, nowhere does the Settlement
Agreement require that Mr. Levine, or any specific officer at Doner,
personally receive notice from Riesett. Nor does the Settlement
Agreement require that notice be sent to Doner’s counsel, as Doner
appears to believe. See Appellant’s Br. at 40. We conclude, as did the
district court, that Riesett’s notice, addressed to Mr. Levine and sent
by certified mail, with the return receipt signed and received, sufficed
to "provide Doner with written notice" of the late payment.

   We are also satisfied that Doner "fail[ed] to make" the delinquent
payment within "five (5) business days of receipt of notice from Rie-
sett," as the certified mail receipt was signed on June 1, 2001 and
Doner did not mail the payment to Riesett until July 31, 2001. Again,
the acceleration clause hinges on whether Doner was provided with
10                RIESETT v. W.B. DONER & COMPANY
notice, not whether Mr. Levine (or any particular officer at Doner)
received notice. We know that someone at Doner received notice and
signed the certified mail receipt. Perhaps this employee dropped the
ball by failing to deliver the package to Mr. Levine, or perhaps Mr.
Levine received the package but forgot about it — he did not deny
receiving the certified mail sent by Riesett, but merely asserted that
he "did not recall" receiving it. J.A. 447. Whatever the story, missteps
by Doner personnel do not render Riesett’s notice defective under the
language of the Settlement Agreement. Riesett fulfilled his obliga-
tions to notify Doner, and Doner failed to make the late payment
within the required five days.

                                   B.

   Notwithstanding Riesett’s notice to Doner, the district court denied
enforcement of the acceleration clause, in part because it believed that
enforcement of the clause would be "unconscionable" given the cir-
cumstances of this case. To the extent the district court’s opinion sug-
gests or intimates that Doner could rely on the unconscionability
doctrine to escape its contractual obligations under the Settlement
Agreement, this was a mistake. When the substantive terms of a con-
tract are so one-sided that a court is led to conclude that some defect
in bargaining process (such as fraud, duress, or incompetence of a
contracting party) led to the formation of the contract, then the uncon-
scionability doctrine may be useful in helping courts ferret out such
contracts, whose enforcement would neither promote the autonomy of
the contracting parties nor enhance social welfare.4 The unconsciona-
bility doctrine has no application to contracts, such as the Settlement
Agreement in this case, which were entered into by sophisticated par-
ties who bargained at arms’ length and were represented by counsel
throughout the negotiations. See Stenke v. Masland Development Co.,
Inc., 394 N.W.2d 418, 424 (Mich. Ct. App. 1986) (refusing to find a

  4
   See, e.g., Northwestern National Insurance Co. v. Donovan, 916 F.2d
372, 377 (7th Cir. 1990) ("Perhaps the correct inference to be drawn
from . . . cases that might be cited is that ‘unconscionability’ is little
more than an umbrella term for fraud, duress, illegality, and violation of
a fiduciary relationship.").
                   RIESETT v. W.B. DONER & COMPANY                        11
lease agreement unconscionable because it was "extensively negoti-
ated by experienced and knowledgeable persons").5

   Doner attempts to defend the district court’s decision not to accel-
erate by claiming that it "substantially performed" its contractual obli-
gations, because the payment arrived 61 days late and Levine
"promptly corrected" the breach when it was brought to his attention.
Doner misunderstands the doctrine of substantial performance. First,
liability for breach of contract is strict, so Doner’s contention that
Levine "acted in good faith" by promptly sending payment to Riesett
once the breach was brought to his attention is not sufficient to estab-
lish that Doner substantially performed its obligations under the set-
tlement agreement. Notwithstanding the observation in Jacob &
Youngs, Inc. v. Kent, 129 N.E. 889 (N.Y. 1921), that the contractor’s
failure to use the Reading pipe specified in the contract had been "un-
intentional," the court’s finding of substantial performance in that
case rested on the facts that the performance was "substantially" what
the homeowner had bargained for and on Judge Cardozo’s belief that
the parties had not sufficiently stated in their contract that use of the
  5
    Neither the parties nor the district court discussed the choice of law
issue for interpretation of the settlement agreement. In the briefs, the par-
ties seem to assume without explanation that Michigan contract law
applies. As a federal court sitting in diversity, we must apply the choice
of law rules of the forum state, see Klaxon Co. v. Stentor Electric Mfg.
Co., 313 U.S. 487 (1941), in this case, Maryland. Absent a choice-of-law
provision in the contract, Maryland applies the law of the jurisdiction
where the contract was made to matters regarding the validity and inter-
pretation of contract provisions, see American Motorists Insurance Co.
v. ARTRA Group, Inc., 659 A.2d 1295, 1301 (Md. 1995), and a contract
is made where the last act necessary to make the contract binding occurs,
see Commercial Union Insurance Co. v. Porter Hayden Co., 698 A.2d
1167, 1200 (1997). See also Continental Cablevision of New England,
Inc. v. United Broadcasting Co., 873 F.2d 717, 720-21 (4th Cir. 1989)
(explaining that, under Maryland choice of law rules, construction of set-
tlement agreement is governed by the law of state to which agreement
was mailed for execution by sole remaining party).
  The settlement agreement was signed first by Donald Riesett on Febru-
ary 14, 2001, and last by Doner’s representative in Michigan on February
19, 2001. The signatures by Doner’s representative would be the "last act
necessary" to make the settlement agreement binding.
12                RIESETT v. W.B. DONER & COMPANY
Reading pipe was a condition precedent to receipt of payment. See
Jacob & Youngs, 129 N.E. at 891 ("This is not to say that the parties
are not free by apt and certain words to effectuate a purpose that per-
formance of every term shall be a condition of recovery. . . . This is
merely to say that the law will be slow to impute the purpose, in the
silence of the parties, where the significance of the default is griev-
ously out of proportion to the oppression of the forfeiture.").
Although a breaching party’s inadvertence may, in some cases, be rel-
evant evidence as to whether the defect was "insubstantial," the doc-
trine of substantial performance ultimately turns on whether "all the
essentials necessary to the full accomplishment of the purposes for
which the thing contracted has been performed with such approxima-
tion that a party obtains substantially what is called for by the con-
tract," Gibson v. Group Insurance Co., 369 N.W.2d 484, 486 (Mich.
Ct. App. 1985) (quoting 6A Michigan Law & Practice, Contracts,
§ 314, pp. 315-316), not on the breaching party’s state of mind.

   The second and more fundamental problem with Doner’s argument
is that parties cannot escape their contractually-chosen remedies for
breach by invoking the doctrine of substantial performance. Although
the doctrine of substantial performance prevents promisee opportun-
ism by forbidding a promisee from walking away from a contract and
refusing to perform his reciprocal contractual duties because of a
minor breach by the promisor,6 it does not mean that a promisor who
"substantially performed" can avoid a lawsuit for damages by the
promisee, or can escape the parties’ chosen remedy for that shortcom-
ing. See 3A Corbin, Contracts § 702 ("Substantial performance" is not
a complete discharge of duty. It is not a defense in a suit . . . for dam-
ages."); People v. Walton, 440 N.W.2d 114, 116 (Mich. Ct. App.
1989) (holding that even where a party substantially performs its con-
tractual obligations, "the other party may be entitled to ‘extra com-
pensation or damages’ as a result of the deviation"). Even if we were
to assume arguendo that Doner’s late payment to Riesett constituted
"substantial performance," it would not render inapplicable the accel-
eration clause. In Jacob & Youngs, notwithstanding the contractor’s
"substantial performance," the court still held that the homeowner was
  6
   See, e.g., Antonoff v. Basso, 78 N.W.2d 604, 610 (Mich. 1956) (if one
party substantially performs, the other may not "refuse to render a recip-
rocally promised performance") (emphasis added).
                  RIESETT v. W.B. DONER & COMPANY                      13
entitled to expectation damages — the difference in the value of the
house resulting from the use of non-Reading pipe. In this case, the
district court (rather than enforcing the acceleration clause) ordered
a make-whole remedy to put Riesett in the position he would have
enjoyed had the late payment not occurred. This would have been an
appropriate remedy if the parties had not agreed to a different remedy
in the Settlement Agreement in the event of a late payment after
notice. But Doner and Riesett bargained around the default rule of
expectation damages and agreed that, in the event of a failure by
Doner to make payment within five days of receipt of notice of
default, all amounts not yet paid would become immediately due and
payable.7

   If courts were to substitute expectation damages for the parties’
chosen remedy under an acceleration clause by talismanic invocation
of "substantial performance," this would have serious ramifications
for commercial lending. Acceleration clauses are essential in lending
agreements because often, if a borrower makes late payments, litiga-
tion costs will dwarf any "expectation damages" (interest on late pay-
ments) that the lender might hope to recover in court. If lenders had
to make do with expectation damages notwithstanding the existence
of an acceleration clause in their agreements, borrowers would have
every incentive to shirk and no incentive to pay on time, because bor-
rowers would know that litigation over late payments would be une-
  7
    Jenkins v. USA Foods, Inc., 912 F. Supp. 969 (E.D. Mich. 1996), on
which Doner heavily relies, is inapposite. In Jenkins, the plaintiff could
not enforce the acceleration clause without violating his reciprocal con-
tractual duty to "cooperate reasonably" with the defendants "to avoid the
undue interruption of [the defendant’s] operations and activities." 912 F.
Supp. at 975. Therefore, because the defendants in Jenkins "substantially
performed" their end of the bargain, the court refused to allow the plain-
tiff to disown his agreements and escape his contractual duties owed to
the defendant by enforcing the acceleration clause.
   In this case, by contrast, Riesett’s enforcement of the acceleration
clause would not violate any contractual duty owed to Doner under the
settlement agreement. The "substantial performance" by a party only pre-
vents the other party from repudiating his contractual promises, and
Doner does not point to a single contractual obligation under the settle-
ment agreement that Riesett has failed to perform or is trying to avoid.
14                RIESETT v. W.B. DONER & COMPANY
conomical for the lender. We cannot accept Doner’s argument that it
can avoid the acceleration clause by relying on the doctrine of sub-
stantial performance.

                                   C.

   Even though enforcement of the acceleration clause cannot be
denied by relying on the doctrines of unconscionability or substantial
performance, neither of the parties, nor the district court, discussed
the Michigan law governing the validity and enforceability of acceler-
ation clauses. Although acceleration clauses are valid and enforceable
in Michigan, see Washburn v. Michailoff, 613 N.W.2d 405, 408
(Mich. Ct. App. 2000), a court may decline to enforce an acceleration
clause where it would be "inequitable" to do so, see State-William
Partnership v. Gale, 425 N.W.2d 756, 759 (Mich. Ct. App. 1988), or
when "an honest dispute exists," see Mitchell v. Dahlberg, 547
N.W.2d 74, 78 (Mich. Ct. App. 1996). The district court did not apply
Michigan law at all, and the factual record is insufficiently developed
for us, as an appeals court, to determine as a matter of first impression
whether enforcement of the acceleration agreement would be "inequi-
table" under Michigan law or whether "an honest dispute exists."
These are fact-bound inquiries, and we will therefore remand this
issue to allow the parties the opportunity to establish, before the dis-
trict court, whether the acceleration clause is valid and enforceable
under Michigan law.

                            CONCLUSION

  The district court’s grants of summary judgment to Doner on Count
XIV and to Riesett on Count XIII are affirmed. The district court’s
denial of Riesett’s motion to enforce the settlement agreement is
vacated and the case is remanded for further proceedings.

                                                        SO ORDERED
