Manufacturers of defective products may be held strictly liable for injury caused by their products -- meaning that they may be liable regardless of privity, foreseeability or reasonable care ( see Codling v Paglia, , 32 NY2d 330, 342 1973]; Prosser & Keeton, Torts § 98 [5th ed]). A product may be defective because of a mistake in the manufacturing process, because of defective design or because of inadequate warnings regarding use of the product ( see Voss v Black & Decker Mfg. Co., , 59 NY2d 102, 106-107 [1983]).

Strict products liability rests on several public policy considerations. In light of the increased complexity of modern products and manufacturing methods, often only the manufacturer "can be fairly said to know and to understand when an article is suitably designed and safely made for its intended purpose" ( Codling, 32 NY2d at 340). Relatedly, the manufacturer alone "has the practical opportunity, as well as considerable incentive, to turn out useful, attractive, but safe products" ( id. at 341).

Strict products liability, moreover, appropriately applies to sellers who engage in product sales in the ordinary course of their business because such sellers "may be said to have assumed a special responsibility to the public, which has come to expect them to stand behind their goods" ( Sukljian v Ross & Son Co., , 69 NY2d 89, 95 [1986]; see Restatement [Second] of Torts, § 402A, Comment c). More generally, the burden of accidental injuries caused by defective products is better placed on those who produce and market them, and should be treated as a cost of business against which insurance can be obtained ( see Restatement [Second] of Torts, § 402A, Comment c; Codling, 32 NY2d at 341).

Those same public policy considerations are inapplicable where sales of the product are not part of the ordinary course of the seller's business. Thus, "casual" or "occasional" sales are not subject to claims of strict liability ( see Gebo v Black Clawson Co., , 92 NY2d 387, 393 [1998]; Stiles v Batavia Atomic Horseshoes, Inc., , 81 NY2d 950, 951 1993]; Sukljian, 69 NY2d at 95-96; see also Annotation, When is a Person "Engaged in the Business" For Purposes of Doctrine of Strict Tort Liability, 99 ALR3d 671).

In Sukljian, for example, we concluded that defendant's sale of a surplus 11-year-old mill on an "as-is" basis was a casual or occasional sale, not subject to a claim of strict products liability, because it was wholly incidental to the seller's regular business. The "casual or occasional seller of a product does not undertake the special responsibility for public safety assumed by those in the business of regularly supplying those products" ( Sukljian, 69 NY2d at 95). Moreover, as a practical matter, the occasional seller "has neither the opportunity, nor the incentive, nor the protection of the manufacturer or seller who puts that product into the stream of commerce as a normal part of its business, and the public consumer does not have the same expectation when it buys from such a seller" ( id.). In Gebo we applied to manufacturers the Sukljian distinction between a casual sale and a market sale in the ordinary course of business, concluding that a defendant who modified a product for its own use, not for market sale, was a casual manufacturer not subject to strict products liability (92 2 at 393).

Here, Conner maintains that it should be free of strict products liability because it only engaged in a one-time, custom fabrication of the retractable floor, and is not a manufacturer of retractable floors. The Appellate Division majority agreed, concluding that the one-time-only work of a custom fabricator "implicates none of the public policy considerations underlying the imposition of strict liability" (294 2 758, 761).

We disagree. True, when a custom fabricator builds a product to suit a customer's specific needs, there may well be less informational disparity between the producer and the user than in the mass production setting. Such disparity is, however, only one of the several policy reasons underpinning strict liability. Like other manufacturers, custom fabricators engaged in the regular course of their business hold themselves out as having expertise in manufacturing their custom products, have the opportunity and incentive to ensure safety in the process of making those products, and are better able to shoulder the costs of injuries caused by defective products than injured consumers or users.

Conner is in the business of manufacturing specialty sheet metal products, and the retractable floor was just such a product -- specifically manufactured for market sale to General Electric. The sale here was not incidental to Conner's normal business, as in Sukljian. Nor was the floor produced for Conner's own use, as in Gebo. The fact that Conner had not previously built such a floor should not preclude the application of strict liability. So long as the product was built for market sale in the regular course of the manufacturer's business, as it was here, strict liability may apply.

Alternatively, Conner argues that summary dismissal of the complaint was appropriate because it had no role in the alleged defective design of the floor.[1] Although not altogether clear on the record before us, there is some evidence that Conner may have participated in the design of the retractable floor. The record also indicates that Conner and General Electric may have collaborated on the installation instructions, and that no provision was made in the design for preventing the floor from separating completely from its moorings. Although plaintiff's expert affidavit was too speculative to create an issue of fact ( see Diaz v New York Downtown Hosp., __ NY2d __ [Dec. 12, 2002]), we conclude that the record otherwise presents disputed issues of fact as to Conner's involvement in the design and installation of the allegedly defective product. At this juncture, plaintiff's complaint against Conner therefore must be reinstated.

Finally, we agree with the Appellate Division that defendant MTR Ravensburg is entitled to summary dismissal of the complaint. There is no evidence in the record that the lathe itself failed to perform as intended, and MTR Ravensburg was not involved in the design, sale or installation of the retractable floor. Nor can it be said on this record that the retractable floor is a necessary component part of the lathe. Thus, MTR cannot be held liable for any possible defect in the retractable floor.

Accordingly, the order of the Appellate Division should be modified, with costs to plaintiff as against defendants V.F. Conner, Inc. and Gordon Bell, by reinstating the complaint against those defendants and, as so modified, affirmed, with costs to defendant MTR Ravensburg Inc. as against plaintiff.