ROSENBLATT, J.:

Plaintiff has brought this personal injury action against defendant, a company that entered into a snow removal contract with a property owner. We are called upon to determine whether the company may be held liable to plaintiff for injuries she sustained when she slipped and fell on the premises. To decide this appeal, we must determine whether a contractor of this type owes a duty to a third person, such as plaintiff.

On January 28, 1998 plaintiff slipped and fell in a parking lot owned by her employer, Miltope Corporation. Attributing her fall to an “icy condition,” plaintiff sued Melville Snow Contractors, the company under contract to plow and remove snow from the premises.[1] She alleged that Melville created the icy condition by negligently removing snow from the parking lot. Melville moved for summary judgment, contending that it owed no duty of care to plaintiff.

Supreme Court denied the motion, concluding that Melville had failed to show that “there was a reasonable explanation for the existence of the ice * * * other than a failure on its part to remove snow and ice in a non-negligent manner.” The Appellate Division reversed, granted Melville's motion for summary judgment and dismissed the complaint. The court held that Melville owed plaintiff no duty of care. Important for purposes of this appeal, the court also held that plaintiff's “allegation that [Melville] created or exacerbated the hazardous condition did not provide a basis for liability.” We now affirm the order of the Appellate Division, but on different grounds.

Because a finding of negligence must be based on the breach of a duty, a threshold question in tort cases is whether the alleged tortfeasor owed a duty of care to the injured party (see Darby v Compagnie Nat'l Air France, , 96 NY2d 343, 347 2001]; Pulka v Edelman, , 40 NY2d 781, 782 [1976]). Here, we must determine whether any such duty ran from Melville to plaintiff, given that Melville's snow removal contract was with the property owner. As we have often said, the existence and scope of a duty is a question of law requiring courts to balance sometimes competing public policy considerations (see e.g. Palka v Servicemaster Mgt. Servs. Corp., , 83 NY2d 579, 585-586 1994]; Eaves Brooks Costume Co. v Y.B.H. Realty Corp., , 76 NY2d 220, 226- 227 [1990]).

Under our decisional law a contractual obligation, standing alone, will generally not give rise to tort liability in favor of a third party (see Eaves Brooks, 76 NY2d at 226). Seventy-four years ago, in H.R. Moch Co. v Rensselaer Water Co. (247 NY 160 [1928]), Chief Judge Cardozo stated that imposing liability under such circumstances could render the contracting parties liable in tort to “an indefinite number of potential beneficiaries” (id. at 168). As a matter of policy, we have generally declined to impose liability to that degree. On the other hand, we have recognized that under some circumstances, a party who enters into a contract thereby assumes a duty of care to certain persons outside the contract (see Palka, 83 NY2d at 586; Strauss v Belle Realty Co., , 65 NY2d 399, 402 1985]). Having rejected the concept of open-ended tort liability, while recognizing that liability to third persons may sometimes be appropriate, we must determine where to draw the line (see De Angelis v Lutheran Med. Ctr., , 58 NY2d 1053, 1055 1983]). Although the “policy-laden” nature of the existence and scope of a duty generally precludes any bright-line rules (Palka, 83 NY2d at 585), three cases help light the way.

Moch, Eaves Brooks and Palka identify contractual situations involving possible tort liability to third persons. Our analysis begins with Moch. There, the defendant entered into a contract with the City of Rensselaer to supply water to the City for various purposes, including water at the appropriate pressure for fire hydrants. A building caught fire and, because the defendant allegedly failed to supply sufficient water pressure to the hydrants, the fire spread and destroyed the plaintiff's warehouse. Although the contract was valid and enforceable as between the City and the defendant, we concluded that the contract was not intended to make the defendant answerable to anyone who might be harmed as a result of the defendant's alleged breach. Because the plaintiff company was not a third-party beneficiary, it could not sue for breach of contract. Nor, we held, could the plaintiff succeed in tort. “[L]iability would be unduly and indeed indefinitely extended by this enlargement of the zone of duty” (Moch, 247 NY at 168). We observed, however, that irrespective of the attendant contractual obligations, tort liability to a third person may arise where “the putative wrongdoer has advanced to such a point as to have launched a force or instrument of harm, or has stopped where inaction is at most a refusal to become an instrument for good” (id. [emphasis added]).

In Eaves Brooks we continued the theme, identifying detrimental reliance as another basis for a contractor's liability in tort to third parties. There, a commercial tenant sought to recover for property damage sustained when a sprinkler system malfunctioned and flooded the premises. The tenant sued the companies that were under contract with the property owner to inspect and maintain the sprinkler system. For policy reasons, we refused to extend liability to encompass the defendant companies, noting that the building owners were in a better position to insure against loss. We adhered to the general rule that “a contractual obligation, standing alone, will impose a duty only in favor of the promisee and intended third-party beneficiaries” (Eaves Brooks, 76 NY2d at 226). We were careful to state, however, that tort liability may arise where “performance of contractual obligations has induced detrimental reliance on continued performance” and the defendant's failure to perform those obligations “positively or actively” works an injury upon the plaintiff (id.).

Finally, in Palka, we considered whether a maintenance company under contract to provide preventive maintenance services to a hospital assumed a duty of care to the plaintiff, a nurse who was injured when a wall-mounted fan fell on her as she was tending to a patient. The contract between the parties was “comprehensive and exclusive” (Palka, 83 NY2d at 584) and required the maintenance company to inspect, repair and maintain the facilities, and to train and supervise all support service personnel. The company's obligation to the hospital was so broad that it entirely displaced the hospital in carrying out maintenance duties and became “the sole privatized provider for a safe and clean hospital premises” (id. at 589). Because the company's contractual obligation was comprehensive, we found this to be another instance in which a contracting provider owed a duty to “noncontracting individuals reasonably within the zone and contemplation of the intended safety services,” including the plaintiff (id.).

In sum, Moch, Eaves Brooks and Palka identify three situations in which a party who enters into a contract to render services may be said to have assumed a duty of care -- and thus be potentially liable in tort -- to third persons: (1) where the contracting party, in failing to exercise reasonable care in the performance of his duties, “launch[es] a force or instrument of harm” (Moch, 247 NY at 168); (2) where the plaintiff detrimentally relies on the continued performance of the contracting party's duties (see Eaves Brooks, 76 NY2d at 226) and (3) where the contracting party has entirely displaced the other party's duty to safely maintain the premises (see Palka, 83 NY2d at 589). These principles are firmly rooted in our case law, and have been generally recognized by other authorities (see e.g. Restatement [Second] of Torts § 324A).