Ordered that the order is affirmed insofar as appealed from, with costs.
On or about September 27, 1982, a tractor trailer owned and operated by the defendants and third-party plaintiffs Malone Freight Lines, Inc. and Nile P. Testerman, respectively, collided with a motor vehicle operated by the third-party defendant. The plaintiff, who was, at the time, a passenger in the vehicle operated by the third-party defendant, submitted a claim for medical benefits against the third-party defendant's insurance carrier. No-fault benefits in the sum of $1,796.42 were paid by the carrier in connection with the plaintiff's claim, whereupon reimbursement was sought against Malone Freight Lines, Inc. The matter proceeded to arbitration as a result of which the carrier was awarded reimbursement in the sum of $898.50 based on a comparative negligence finding of 50% against Malone Freight Lines, Inc.
The relationship between the insured and the insurer as payor of first-party benefits is not that of indemnitor-indemnitee and the liability for such payments is not dependent upon or derivative from any liability of the insured (Baldwin v. Brooks, 83 A.D.2d 85, 88-89). Inasmuch as the third-party defendant was not a party to the arbitration proceeding, did not have a unity of interest with respect to the matter arbitrated and was not afforded a full and fair opportunity to contest that determination, the third-party defendant should not be bound by the arbitrator's ancillary finding regarding comparative negligence (see, Samhammer v. Home Mut. Ins. Co., 120 A.D.2d 59, 64; Compton v. D'Amore, 101 A.D.2d 800, 801).
In accordance with the well-settled tenet that the doctrine of collateral estoppel "`is essentially a rule of justice and fairness'" (Hinchey v. Sellers, 7 N.Y.2d 287, 294, quoting Commissioners of State Ins. Fund v. Low, 3 N.Y.2d 590, 595), the issues of apportionment of liability and contribution, if any, between the defendants and third-party plaintiffs and the third-party defendant were properly left for resolution by the trier of fact. Mollen, P.J., Thompson, Lawrence and Weinstein, JJ., concur.