Citing Power-Matics, Inc. v. Ligotti , 79 N.J.Super. 294, 191 A.2d 483, 490 (App. Div. 1963), Plaintiffs argue that "the existence of an express contract is not an outright bar to an unjust enrichment claim" under New Jersey law. (Pls.' Br. 32).
A quasi-contract rests on the equitable principle that a person should not be allowed to enrich himself unjustly at the expense of another and is sometimes imposed "even against a clear expression of dissent." St. Paul Fire &Marine Ins. Co. v. Indemnity Ins. Co. of North America, 32 N.J. 17, 22, (1960); Power-Matics, Inc. v. Ligotti, 79 N.J.Super. 294, 305-06, (App.Div.1963); Deskovick v. Porzio, 78 N.J.Super. 82, 87-88, (App.Div.1963); 1 Corbin on Contracts § 19; 1 Williston on Contracts § 3A (3d ed. 1957). However, generally, the parties are bound by their agreement, and there is no ground for imposing an additional obligation where there is a valid contract that governs their rights.
Generally, a contractor who "substantially perform[s]" the contract is entitled "to recover the contract price less . . . a fair allowance to the owner to make good the defects." R. Krevolin & Co. v. Brown, 20 N.J.Super. 85, 89 (App. Div. 1952) (quoting Reese v. Kline Bldg. & Constr. Co., 8 N.J. Misc. 296, 297 (1930)); see also Power-Matics, Inc. v. Ligotti, 79 N.J.Super. 294, 303 (App. Div. 1963). "Substantial performance is compliance in good faith with all important particulars of the contract."
R. Krevolin & Co. v. Brown, 20 N.J. Super. 85, 89 (App. Div. 1952) (internal quotations omitted) (quoting Reese v. Kline Bldg. & Const. Co., 8 N.J. Misc. 296, 297 (1930)); see also Power-Matics, Inc. v. Ligotti, 79 N.J. Super. 294, 303 (App. Div. 1963). "Substantial performance is compliance in good faith with all important particulars of the contract." Jardine Estates, Inc. v. Donna Brook Corp., 42 N.J. Super. 332, 337 (App.