No question has been raised on this appeal as to the plaintiffs having introduced sufficient evidence to establish a claim for unjust enrichment against the defendants. The sole question on this appeal is whether there is sufficient evidence to support an award of damages by the jury. We hold there was sufficient evidence and reverse the Court of Appeals.
The Restatement of Restitution § 1 lays down the general principle that “[a] person who has been unjustly enriched at the expense of another is required to make restitution to the other.” In order to establish a claim for unjust enrichment, a party must have conferred a benefit on the other party. The benefit must not have been conferred officiously, that is it must not be conferred by an interference in the affairs of the other party in a manner that is not justified in the circumstances. The benefit must not be gratuitous and it must be measurable. See Britt v. Britt, 320 N.C. 573, 359 S.E. 2d 467 (1987) and E. Allan Farnsworth, Contracts § 2.20. In Wells v. Foreman, 236 N.C. 351, 72 S.E. 2d 765 (1952), we said that the defendant must have consciously accepted the benefit. A claim of this type is neither in tort nor contract but is described as a claim in quasi contract or a contract implied in law. A quasi contract or a contract implied in law is not a contract. The claim is not based on a promise but is imposed by law to prevent an unjust enrichment. If there is a contract between the parties the contract governs the claim and the law will not imply a contract. Concrete Co. v. Lumber Co., 256 N.C. 709, 124 S.E. 2d 905 (1962). Our cases hold that the measure of damages for unjust enrichment is the reasonable value of the goods and services to the defendant. Johnson v. Sanders, 260 N.C. 291, 132 S.E. 2d 582 (1963); Environmental Landscape Design v. Shields, 75 N.C. App. 304, 330 S.E. 2d 627 (1985); Hood v. Faulkner, 47 N.C. App. 611, 267 S.E. 2d 704 (1980); Harrell v. Construction Co., 41 N.C. App. 593, 255 S.E. 2d 280 (1979), affirmed, 300 N.C. 353, 266 S.E. 2d 626 (1980).
The question posed by this appeal is whether there is sufficient evidence to support a finding by the jury that the reasonable value of the goods and services to the defendants for which the plaintiff has not been paid is $26,000.00 for the Wilkes Towers project and $40,500.00 for the Sheraton Towers project. In deter*571mining this question we take into account the finding of the jury that there was not a contract between the parties. This means the plaintiff furnished material and labor to the defendants for a substantial period without a contract and the defendants paid for it. This is some evidence of the value of the goods and labor furnished before the defendants stopped paying. The evidence was undisputed that the plaintiff furnished a substantial quantity of materials and labor after the last payment by the defendants. This was obviously of value. The plaintiffs bookkeeper testified to the total billing to the defendants and to the amount paid and unpaid by the defendants. We hold that her testimony as to what was billed for the materials and labor and the evidence of a payment for a part of it at the billed rate is evidence sufficient for the jury to find the reasonable value to the defendants of the remaining goods and services for which bills were submitted and no payment was made. This case is somewhat analogous to Environmental Landscape Design v. Shields, 75 N.C. App. 304, 330 S.E. 2d 627, in which our Court of Appeals held that the plaintiffs bill together with the hourly rate charged by another landscape designer who worked on the job were sufficient to establish the reasonable value of the plaintiffs services. In this case we have the plaintiffs bill and the previous payment to the plaintiff in accordance with the bill.
The Court of Appeals has held that an invoice or bill alone is not sufficient evidence to support a jury award as to the reasonable value of services. Harrell v. Construction Co., 41 N.C. App. 593, 255 S.E. 2d 280. We expressly declined to rule on that question in Harrell v. Construction, 300 N.C. 353, 266 S.E. 2d 626. It is not necessary for us to decide this question in this case because there is more evidence than the amount billed to the defendants.
 In a cross assignment of error, the defendants ask that if we hold there was sufficient evidence of damages to support the jury award, that we exercise our discretion pursuant to N.C.G.S. § 1A-1, Rule 50(d) and order a new trial on the damage issue. They say that because the court reserved a ruling on their motion for directed verdict made at the close of the plaintiffs evidence, they did not offer evidence of unjust enrichment for fear of making the plaintiff s case for him. The defendants argue they should now be allowed to use this evidence. We do not believe the trial *572tactics employed by the defendants is sufficient reason for us to exercise our discretion and order a new trial.
For the reasons stated in this opinion, we reverse the order of the Court of Appeals and remand the case with instructions that it be remanded to superior court for the entry of a judgment in accordance with the verdict of the jury.
Reversed and remanded.