Full opinion text
MEMORANDUM AND ORDER WEINSTEIN, District Judge. These two cases arise out of eighteen separate accidents scattered across the nation in which children were injured by blasting caps. Damages are sought from manufacturers and their trade association, the Institute of Makers of Explosives (I.M.E.). The basic allegation is that the practice of the explosives industry during the 1950’s — continuing until 1965 — of not placing any warning upon individual blasting caps and of failing to take other safety measures created an unreasonable risk of harm resulting in plaintiffs’ injuries. In most instances the manufacturer of the cap is unknown. The question posed is whether a group of manufacturers and their trade association, comprising virtually the entire blasting cap industry of the United States, can be held jointly liable for injuries caused by their product. Our answer is that there are circumstances, illustrated by this litigation, in which an entire industry may be liable for harm caused by its operations. While the cases are closely linked in their litigation history and underlying legal theory, they differ in several crucial respects. See Hall v. E. I. Du Pont De Nemours & Co., 312 F.Supp. 358 (E.D.N.Y.1970) for an earlier phase of the litigation. In Chance, the name of the manufacturer who actually produced the cap causing a particular injury is apparently unknown. In Hall it is, plaintiffs allege, known. We turn to Charpce first since it presents the more difficult legal problems. I. THE CHANCE CASE A. Facts and Proceedings Thirteen children were allegedly injured by blasting caps in twelve unrelated accidents between 1955 and 1959. The injuries occurred in the states of Alabama, California, Maryland, Montana, Nevada, North Carolina, Tennessee, Texas, Washington and West Virginia. Plaintiffs are citizens of the states in which their injuries occurred. They are now claiming damages against six manufacturers of blasting caps and the I.M.E. on the grounds of negligence, common law conspiracy, assault, and strict liability in tort. In addition, two parents sue for medical expenses. Federal jurisdiction is based on diversity of citizenship. 28 U.S.C. § 1332. While the plaintiffs’ injuries occurred at widely varied times and places, the complaint alleges certain features common to them all. Each plaintiff, according to the complaint, “came into possession” of a dynamite blasting cap which was not labeled or marked with a warning of danger, and which could be easily detonated by a child; In each instance an injurious explosion occurred. The complaint does not identify a particular manufacturer of the cap which caused a particular injury. It alleges that each cap in question was designed and manufactured jointly or severally by the six corporate defendants or by other unnamed manufacturers, and by their trade association, the I.M.E. Plaintiffs’ central contention is that injuries were caused by the defendants’ failure to place a warning on the blasting caps, and to manufacture caps which would have been less easily detonated. This failure, according to the plaintiffs, was not the result of defendants’ ignorance of the dangerousness of their product to children. The complaint states that the defendants had actual knowledge that children were frequently injured by blasting caps, and, through the trade association, kept statistics and other information regarding these accidents. Recognizing the dangerousness of their product to children, the defendants, through the trade association, used various means — such as placards and printed notices — to warn users of the caps and the general public. These measures were allegedly inadequate in light of the known risks of injury. Moreover, defendants are said to have jointly explicitly considered the possibility of labeling the caps, to have rejected this possibility, and to have engaged in lobbying activities against legislation which would have required such labeling. The long-standing industry practice of not placing a warning message on individual blasting caps was, it is urged, the result of a conscious agreement among the defendants, in the light of known dangers, with regard to this aspect of their product. The six corporate defendants are: E. I. Du Pont De Nemours & Co., Inc. (“Du Pont”), Hercules Powder Co. (“Hercules”), and Atlas Powder Co. (“Atlas”), all citizens of and having their principal places of business in Delaware; American Cyanamid Co. (“Cyanamid”), a citizen of Maine with its principal place of business in New Jersey; Olin Mathieson Chemical Corp. (“Olin”), a citizen of Virginia with its principal place of business in Connecticut; and Austin Powder Co. (“Austin”), a citizen of and having its principal place of business in Ohio. The defendant I.M.E. is an unincorporated association with its principal place of business in New York. , Defendants move to dismiss on the grounds that the plaintiff-children do not state claims upon which relief can be granted. They also request dismissal of the parents’ claims for medical expenses as barred by statutes of limitations. Finally, they seek a severance on the grounds óí improper joinder and transfer of the severed claims or their outright dismissal on the ground of inconvenient forum. 28 U.S.C. § 1404(a). B. Issues Presented The issues common to products liability cases are well known: did the manufacturer (or other supplier) violate a duty of care to plaintiffs, and was the violation a legal or “proximate” cause of plaintiffs’ injuries. 2 Harper & James, The Law of Torts §§ 28.1-.2 (1956). Moving to dismiss the complaint, defendants have the burden of showing “beyond doubt” that plaintiff “can prove no set of facts in support of his claim which would entitle him to relief.” Conley v. Gibson, 355 U.S. 41, 45-46, 78 S. Ct. 99, 102, 2 L.Ed.2d 80, 84 (1957). A central question raised by defendants’ motion is whether their parallel safety practices provide a basis for joint liability. Interlaced with the issues of duty to warn, proximate cause, and joint liability is a conflicts question of considerable complexity: what choice-of-law principles are to be applied in a case such as. this one where planning, design, manufacture, and sale of a product occurred in different states, and injury in yet others ? Since, as indicated below, further briefs will be required on the choice-of-law problem, we have, for the purposes of this memorandum, assumed the existence of a national body of state tort law. A growing consensus on the substantive law in this country permits such a gross first approach to the preliminary motions before us since all we need to determine now is whether the plaintiffs might succeed on the law and facts. See, e. g., Wright v. Carter Products, 244 F.2d 53, 56-60 (2d Cir. 1956) (Massachusetts law applicable but general treatises, articles and case law of other states cited on motion to dismiss). Under both negligence and strict liability standards manufacturers and other suppliers have a duty to users, consumers, and in some circumstances to the general public or portions of it, to produce products with appropriate warnings, instructions, and other safety features. See, e. g., Noel, Manufacturer’s Negligence of Design or Directions for Use of a Product, 71 Yale L.J. 816 (1962); Noel, Products Defective Because of Inadequate Directions or Warnings, 23 Sw.L.J. 256 (1969); Rest.2d Torts § 388, comment e, § 402A, comments j, l (1965) (warnings under negligence and strict liability standards). Defendants’ duty of care is basic to liability, and we turn first to that issue. C. Duty to Warn and Standard of Care (1) Negligence A manufacturer’s duty to produce a safe product, with appropriate warnings and instructions where necessary, rests initially on the responsibility each of us bears to exercise care to avoid unreasonable risks of harm to others. See, e. g., 2 Harper & James, The Law of Torts § 28.3 (1956). An “unreasonable risk” in any given situation depends on the balancing of probability and seriousness of harm if care is not exercised against the costs of taking precautions. See, e. g., United States v. Carroll Towing Co., 159 F.2d 169, 173 (2d Cir. 1947); 2 Harper & James, supra §§ 16.9, 28.4; Rest. 2d Torts §§ 291-293, 298 (1965). Activity involving a small likelihood of death or serious injury may require greater and more costly precautions than that involving a higher probability of lesser harm. See, e. g., The Glendola, 47 F.2d 206, 207 (2d Cir. 1931), cert. denied, 283 U.S. 857, 51 S. Ct. 650, 75 L.Ed. 1463 (1931); Rest. 2d Torts § 388, comment n at 309 (1965); 2 Harper & James, The Law of Torts § 16.9 at 931-32 (1956). Where an act involves a risk of death or serious bodily harm, and particularly if it is capable of causing such results to a number of persons, the highest attention and caution are required even if the act has a very considerable utility. Thus those who deal with firearms, explosives, poisonous drugs, or high tension electricity are required to exercise the closest attention and the most careful precautions, not only in preparing for their use but in using them. Rest. 2d Torts § 298, comment b at 69 (1965). (а) Standard of Care In most products liability cases the court does not have to make an explicit determination that the defendant owed the plaintiff a duty of reasonable care. The general scope of such a duty is well established: manufacturers must provide products that are reasonably safe for their foreseeable use. See, e. g., MacPherson v. Buick Motor Co., 217 N.Y. 382, 111 N.E. 1050 (1916); Rest. 2d Torts § 395 (1965); 2 Harper & James, The Law of Torts §§ 28.3-.9 (1956). [б] In the explosives industry, producers have long been on notice that they have an obligation to users of their products to guard against defects (Dement v. Olin-Mathieson Chemical Corp., 282 F.2d 76, 80 (5th Cir. 1960)) and “to adequately warn a foreseeable purchaser or user of foreseeable and latent dangers upon proper and intended use of [the] product.” Littlehale v. E. I. Du Pont De Nemours & Co., 268 F.Supp. 791, 798 (S.D.N.Y.1966), aff’d, 380 F.2d 274 (2d Cir. 1967). Similarly, those who use or store explosives have been held to a high standard of care, commensurate with the obvious dangers, to maintain storage facilities that are secure against tampering by children. See e. g., Lone Star Gas Co. v. Parsons, 159 Okl. 52, 14 P.2d 369 (1932); Annot., 10 A.L.R.2d 22 (1950); 2 Harper & James, The Law of Torts § 20.5 at 1144, n. 34 (1956). Defendants suggest, nevertheless, that because the plaintiff-children were neither purchasers nor intended users of the caps, their injuries were “unforeseeable” as a matter of law, and hence outside the scope of the duty of reasonable care. While cast in terms of foreseeability- — a term of the experiential world — the issue is finally one of duty — a question of law and public policy. Green, The Causal Relation Issue in Negligence Law, 60 Mich.L.Rev 543, 562-569 (1962). Because foreseeability is one of the vectors bearing on the finding of duty, we must analyze the meaning of the term in the context of this case. (i) Foreseeability “Foreseeability” at this stage of decision includes two related elements. The first is the likelihood or probability of harm if reasonable care is not exercised — “whether the harm threatened is likely to occur.” Noel, Manufacturer’s Negligence of Design or Directions for Use of a Product, 71 Yale L.J. 816, 830 (1962). The second element is the manufacturer’s actual or constructive knowledge of the risk- — “whether the manufacturer was in a position to foresee the likelihood of such harm.” Id. at 847. The probability of the known risk needed to trigger the duty of reasonable care cannot be expressed in a mathematical formula. Judge Cardozo suggested that “[t]here must be knowledge of a danger, not merely possible, but probable.” MacPherson v. Buick Motor Co., 217 N.Y. 382, 389, 111 N.E. 1050, 1053 (1916). Since “probabilities” are but quantifications of “possibilities,” what is meant in MacPherson is apparently a probability so low that it can be ignored in our everyday world. Judge Learned Hand, discussing foreseeability and scope of reasonable care in the context of proximate cause, utilized much the same formulation: “[The injurious result] has got to be one of those consequences which is not entirely outside the range of expectation or probability, as ordinary men view it.” The Mars, 9 F. 2d 183, 184 (S.D.N.Y.1914). Judge Frank, adopting language of the New Hampshire Supreme Court, argued that the proper threshold test of the applicability of reasonable care “is not of the balance of probabilities, but of the existence of some probability of sufficient moment to induce action to avoid it on the part of a reasonable mind.” Tullgren v. Amoskeag Mfg. Co., 82 N.H. 268, 276, 133 A. 4, 8 (1926), cited with approval in Hentschel v. Baby Bathinette Corp., 215 F.2d 102, 106 (2d Cir. 1954) (Frank, J., dissenting), cert, denied, 349 U.S. 923, 75 S.Ct. 663, 99 L.Ed. 1254 (1955), and in Pease v. Sinclair Refining Co., 104 F.2d 183, 186 (2d Cir. 1939); cf. 2 Harper & James, The Law of Torts § 18.2 at 1018-1026, particularly at 1020 (1956). Whatever the verbal formulation, the concept of “foreseeable risk” is universally taken to mean the foreseeability of a general kind or type of risk, rather than the foreseeability of the precise chain of events leading to the particular injury in question. See, e. g., Pease v. Sinclair Refining Co., 104 F.2d 183, 186-87 (2d Cir. 1939); 2 Harper & James, The Law of Torts § 18.2 at 1026, § 20.5 at 1147-49 (1956). The related issue of whether the manufacturer was in a position to foresee the risk turns on whether “the manufacturer knew, or through the exercise of reasonable care should have known, of the existence of the danger.” Dillard & Hart, Products Liability: Directions for Use and the Duty to Warn, 41 Va.L.Rev. 145, 156-57 (1955). Plaintiffs must demonstrate actual notice to the manufacturer of particular kinds of risks (see, e. g., Noel v. United Aircraft Corp., 219 F.Supp. 556, 568-69 (D.Del.1963), aff’d in pertinent part, 342 F.2d 232 (3d Cir. 1965), or reasonable inferences from known characteristics of the product and its use. See, e. g., Larsen v. General Motors Corp., 391 F.2d 495, 501-505 (8th Cir. 1968); Simpson Timber Co. v. Parks, 369 F.2d 324 (9th Cir. 1966) and 369 F.2d 324, 333-35 (9th Cir. 1966) (Browning, Hanley, Merrill, and Duniway, JJ., dissenting), vacated sub nom. Parks v. Simpson Timber Co., 388 U.S. 459, 87 S.Ct. 2115, 18 L.Ed.2d 1319 (1967), discussed in Noel, Products Defective Because of Inadequate Directions or Warnings, 23 Sw.L.J. 256, 275-77 (1969); see also Noel, Manufacturer’s Negligence of Design or Directions for Use of a Product, 71 Yale L.J. 816, 834-36, 856-66 (1962). The plaintiffs’ injuries in this case are within the range of reasonable expectation and probability. They are likely to occur in the absence of reasonable care. The manufacturer has capacity to foresee them. Plaintiffs allege that the manufacturers not only “had reason to know,” but that they actually knew, through information collected by the trade association, that children were injured in accidents involving blasting caps. According to statistics submitted by the plaintiffs, the number of such accidents between 1955 and 1959 which were known to the manufacturers ranged from 86 to 137 per year. See statistical tables said to be based on I.M.E. data submitted as Exhibits 2A and 2B, Plaintiffs’ Memorandum in Opposition, August 26, 1971, in Hall v. Du Pont, 69-C-273. Defendants do not deny that they had knowledge of these accidents. They claim to have taken all reasonable feasible steps to reduce the risk of their occurrence. Moreover, they argue that they did not deal with plaintiffs, never saw them, and are in court today only through a third party’s carelessness, thus invoking (in part) the familiar doctrine that limits a manufacturer’s liability to injuries caused by his product when put to its “intended use.” A manufacturer’s liability for failure to exercise reasonable care ordinarily extends only to “those who use [the product] for a purpose for which the manufacturer should expect it to be used and . . . those whom [the manufacturer] should expect to be endangered by its probable use” when “physical harm is caused to them by [the product’s] lawful use in a manner and for a purpose for which it is supplied.” Rest. 2d Torts § 395 (1965). Comment j to section 395 of the Second Restatement of Torts, titled “Unforeseeable use or manner of use,” explains that: The liability stated in this Section is limited to persons who are endangered and the risks which are created in the course of uses of the chattel which the manufacturer should reasonably anticipate. In the absence of special reason to expect otherwise, the maker is entitled to assume that his product will be put to a normal use, for which the product is intended or appropriate; and he is not subject to liability when it is safe for all such uses, and harm results only because it is mishandled in a way which he has no reason to expect, or is used in some unusual and unforeseeable manner. See also Mazzi v. Greenlee Tool Co., 320 F.2d 821, 823 (2d Cir.1963) (applying New York law and collecting cases and authorities). This doctrine has been applied in two cases involving explosives manufacturers to insulate them from liability when their products, manufactured for specialized purposes, came into the possession of untrained third parties who were injured while using them. See Littlehale v. E. I. Du Pont De Nemours & Co., 268 F.Supp. 791 (S.D.N.Y.1966), aff’d, 380 F.2d 274 (2d Cir.1967); Harper v. Remington Arms Co., 156 Misc. 53, 280 N.Y.S. 862 (Sup.Ct.1935), aff’d mem., 248 App.Div. 713, 290 N.Y.S. 130 (1st Dep’t 1936), leave to appeal denied, 272 N.Y. 675 (1936). Despite the general validity of the intended use principle, it does not warrant a conclusion that the blasting cap manufacturers in this case'had no duty of reasonable care to the plaintiff-children. The doctrine of intended use is an illustration of the broader doctrine of foreseeability. A manufacturer cannot ignore a probable “misuse” of his product. This interpretation is shared by many courts including the Fourth Circuit in Spruill v. Boyle-Midway, Inc., 308 F.2d 79 (1962), the Eighth Circuit in Larsen v. General Motors Corp., 391 F.2d 495 (1968), and the Second Circuit in Mazzi v. Greenlee Tool Co., 320 F.2d 821 (1963). As the Fourth Circuit pointed out, in a case involving a child’s death from eating furniture polish, “Intended use” is but a convenient adaptation of the basic test of “reasonable foreseeability” framed to more specifically fit the factual situations out of which arise questions of a manufacturer’s liability for negligence. “Intended use” is not an inflexible formula to be apodictically applied to every case. Normally a seller or manufacturer is entitled to anticipate that the product he deals in will be used only for the purposes for which it is manufactured and sold; thus he is expected to reasonably foresee only injuries arising in the course of such use. However, he must also be expected to anticipate the environment which is normal for the use of his product and where, as here, that environment is the home, he must anticipate the reasonably foreseeable risks of the use of his product in such an environment. These are risks which are inherent in the proper use for which his product is manufactured. Thus where such a product is an inherently dangerous one, and its danger is not obvious to the average housewife from the appearance of the product itself, the manufacturer has an obligation to anticipate reasonably foreseeable risks and to warn of them, though such risks may be incidental to the actual use for which the product was intended. Spruill v. Boyle-Midway, Inc., 308 F.2d 79, 83-84 (1962). Applying this analysis to the field of automobile safety, the Eighth Circuit concluded that Automobiles are made for use on the roads and highways in transporting persons and cargo to and from various points. This intended use cannot be carried out without encountering in varying degrees the statistically proved hazard of injury-producing impacts of various types. The manufacturer should not be heard to say that it does not intend its product to be involved in any accident when it can easily foresee and when it knows that the probability over the life of its product is high, that it will be involved in some type of injury-producing accident. Larsen v. General Motors Corp., 391 F.2d 495, 501-502 (1968). The Second Circuit endorsed a similar approach in Mazzi, when it held that the evidence in the case would support a jury verdict “that such usage was intended or that defendant should have reasonably foreseen that its [product] would be so used. . . .” Mazzi v. Greenlee Tool Co., 320 F.2d 821, 825 (1963). See also 2 Harper & James, The Law of Torts § 28.4 at 1541, n. 2 (1956) and Supplement at 215 (1968). In the context of this approach to the problem of intended use, we find the complaint in this case easily distinguishable from the plaintiffs’ position in Littlehale v. E. I. Du Pont De Nemours & Co., 268 F.Supp. 791 (S.D.N.Y.1966), aff’d, 380 F.2d 274 (2d Cir.1967) and in Harper v. Remington Arms Co., 156 Misc. 53, 280 N.Y.S. 862 (Sup.Ct.1935), aff’d mem., 248 App.Div. 713, 290 N.Y.S. 130 (1st Dep’t 1936). In Littlehale defendant Du Pont had manufactured blasting caps under government contract for use by Army Ordnance personnel. The trial court found that “the user [Army Ordnance] was as well or more fully informed of the hazards involved and the correct methods of use as was the manufacturer” (268 F.Supp. at 803), and hence the manufacturer was under no duty to warn its customer of “generally known risks.” 268 F.Supp. at 798. Such a duty could not arise, the trial court concluded, “at some later date by reason of some unforeseeable disposition of the product by [the] initial purchaser.” 268 F.Supp. at 803. In reaching this conclusion, the trial court stressed that [this] is not a case involving a product manufactured for sale or resale to the general public. It is not a case involving negligence in the manufacture, design or use of materials. It is not a case where the manufacturer had any freedom of choice as to manufacture, design, or use of materials. It is not a case where evidence has been submitted upon which foreseeability of the particular use involved herein could be predicated. 268 F.Supp. at 801-02 (citations omitted). In these circumstances, the Second Circuit found the trial court justified in concluding that “as a matter of law du Pont . . . could not have foreseen that its detonators would be used by a person untrained in.the handling of such explosives and in a manner that was never intended.” Littlehale v. E. I. Du Pont De Nemours & Co., 380 F.2d 274, 276 (2d Cir.1967). Plaintiffs’ allegations in this case present a different picture. The complaint promises submission of evidence that the manufacturers not only could have foreseen, but actually did foresee that “[their] detonators would be used by [persons] untrained in the handling of explosives and in a manner that was never intended.” Id. In contrast to the rigid wartime specifications involved in the production of the caps in Littlehale, the defendants in this case apparently had complete freedom of choice as to manufacture, design, and use of materials, and exercised that choice, in the words of a Du Pont employee, in a manner “keyed to the needs of our customers.” Ramsdell affidavit, Sept. 3, 1971, p. 3. While no allegations have been made about whether the caps involved in this case were manufactured for sale to “the general public,” it is clear that their use and circulation was expected to be considerably more widespread than purchase and use by a specialized government agency. Cf. 34 Fed.Reg. 5838 (March 28, 1969) (warning re blasting caps to “Keep out of the reach of children”). Because of these differences, we cannot conclude, as did the trial court in Littlehale, that (1) there is no factual dispute “as to the identity of the intended and actual purchaser [or user]” and (2) that, as a matter of law, plaintiffs are excluded from the foreseeable “orbit of danger.” Littlehale v. E. I. Du Pont De Nemours & Co., 268 F. Supp. 791, 801 (S.D.N.Y.1966). The Harper ease is distinguishable on similar grounds. In that case the defendant manufacturer had produced shot-gun shells of special explosive force for use in arms testing and they were marked to warn the class who would use them for this purpose. A jury verdict for the plaintiff was reversed because the plaintiff “failed to show that he was a person whom the defendant might reasonably have anticipated would use these shells” and hence was not owed a duty of warning and reasonable care by the manufacturer. Harper v. Remington Arms Co., 156 Misc. 53, 58, 280 N.Y.S. 862, 868 (Sup.Ct.1935), aff’d mem., 248 App.Div. 713, 290 N.Y.S. 130 (1st Dep’t 1936). The allegations in the present case preclude a decision at this stage that children were not foreseeable users of blasting caps. Even if the blasting cap manufacturers’ own definition of their product’s intended use were accepted as controlling, plaintiffs have alleged that the manufacturers had, in the words of comment j of section 395 of the Second Restatement of Torts, “special reason to expect” unusual uses of their product by children. A manufacturer’s actual knowledge of unusual risks is the archetype reason for extending his duty of reasonable care beyond the scope of his product’s normally intended use. See, e.g., Simpson Timber Co. v. Parks, 369 F.2d 324, 327-28 (9th Cir.1966), vacated on other grounds sub nom. Parks v. Simpson Timber Co., 388 U.S. 459, 87 S.Ct. 2115, 18 L.Ed.2d 1319 (1967). As the Eighth Circuit has pointed out, the Simpson case now stands for the broad proposition that a manufacturer has a duty of reasonable care with respect to unintended uses “where the injury resulting from that unintended use was foreseeable or should have been anticipated.” Larsen v. General Motors Corp., 391 F.2d 495, 501 (1968) (citations omitted) (emphasis supplied). Application of general principles of foreseeability and reasonable care to unintended uses is not peculiar to modern products liability cases. A similar approach can be found in numerous cases decided in the nineteenth and early twentieth centuries involving children playing with railroad turntables, dynamite blasting caps, and other dangerous instruments and machines. Even in an era when landowners had very limited duties of care to trespassers, many courts recognized that the likelihood of children playing with dangerous instruments was sufficiently foreseeable to impose a duty of care on the owners to provide appropriate locks, fences, notices, storage sheds, and other safety devices. See, e.g., Sioux City and P. R. Co. v. Stout, 84 U.S. 657, 17 Wall. 657, 21 L.Ed. 745 (1873) (affirming jury finding of owner’s negligence to children in failing to provide turntable lock); Edgington v. Burlington, C. R. & N. Ry. Co., 116 Iowa 410, 90 N.W. 95 (1902) (discussing numerous aspects of foreseeable danger to children from turntables) ; Lone Star Gas Co. v. Parsons, 159 Okl. 52, 14 P.2d 369 (1932) (finding liability of landowner to trespassing children for negligent storage of blasting caps); see also Lynch v. Nurdin, 1 Q.B. 29, 113 Eng.Rep. 1041 (1841) Prosser, Law of Torts § 59 at 364-376 (4th ed.1971); 2 Harper & James, The Law of Torts § 18.2 at 1020 (1956). The doctrines evolved in these cases are now embodied in section 339 of the Second Restatement of Torts. According to Dean Prosser’s commentary on this section and its judicial antecedents, the foreseeability elements of landowners’ liability to children are very similar to the foreseeability issues involved in manufacturers’ liability for unintended uses. The possessor must know “or have reason to know that children are likely to trespass,” and the condition in question “must be one which the occupiers should recognize as involving an unreasonable risk of harm to such children.” Prosser, Law of Torts § 59 at 368, 369 (4th ed. 1971). Whether failing to guard against the known risk is unreasonable is in turn determined by the general negligence principles of probability (including obviousness), seriousness of harm and cost of taking appropriate precautions. Id. at 369-71, 375-76. Plaintiffs’ allegations provide a basis for finding that injuries to children were a foreseeable risk of the use and circulation of blasting caps, and that this risk was known to, or should have been known to, the individual manufacturers. It must be emphasized that we are not holding, at this stage, that the defendants in this case had a duty of reasonable care to each of the plaintiff-children. That decision can be made only after presentation of facts relevant to the risk and cost analysis, and determination of any conflict of laws issues. (ii) Costs and Social Utility While foreseeability of risk is an essential element of a finding that a manufacturer is under a duty of care to persons in a particular position, it is not the only element in the decision. An important factor is the cost of taking precautions against the danger. The declaration that a duty or standard of reasonable care is applicable to an injury-causing situation involves various and sometimes delicate policy judgments. The social utility of the activity out of which the injury arises, compared with the risks involved in its conduct; the kind of person with whom the actor is dealing; the workability of a rule of care, especially in terms of the parties’ relative ability to adopt practical means of preventing injury; the relative ability of the parties to bear the financial burden of injury and the availability of means by which the loss may be shifted or spread; the body of statutes and judicial precedents which col- or the parties’ relationship; the prophylactic effect of a rule of liability; . . . . and finally, the moral imperatives which judges share with their fellow citizens — such are the factors which play a role in the determination of duty. Raymond v. Paradise Unified School Dist. of Butte County, 218 Cal.App.2d 1, 8, 31 Cal.Rptr. 847, 851-52 (3d Dist.1963). See also Lone Star Gas Co. v. Parsons, 159 Okl. 52, 56-57 14 P.2d 369, 373-74 (1932); Chicago B. & Q. R. Co. v. Krayenbuhl, 65 Neb. 889, 902-04, 91 N.W. 880, 882-83 (1902); Prosser, Palsgraf Revisited, 52 Mich.L.Rev. 1, 15 (1953). In many situations the “cost” or “social utility” side of the initial calculus of duty is relatively clear-cut. For example, the cost of printing and attaching labels and other warning devices is often regarded as trivial compared to the risk of any substantial harm. See, e.g., Butler v. L. Sonneborn Sons, Inc., 296 F.2d 623, 625-26 (2d Cir.1961); Wright v. Carter Products, Inc., 244 F.2d 53, 59 (2d Cir. 1957); Pease v. Sinclair Refining Co., 104 F.2d 183, 186 (2d Cir.1939). This may not be such a case. The defendants have indicated that there was doubt about the technical feasibility of labeling individual blasting caps during the 1950’s, or of producing caps which could be less easily detonated by children, and that in any event the costs would have been substantial. Such facts, if proven, are clearly relevant to the question of defendants’ duty of care, but they do not warrant a judgment in their favor on a motion to dismiss. Where the foreseeable risks of a product’s use are sufficiently serious — particularly to large numbers of people— courts have not hesitated to require manufacturers to face substantial costs in warnings, testing, inspection, and safety design. See, e.g., Larsen v. General Motors Corp., 391 F.2d 495 (8th Cir.1968); Manos v. Trans World Airlines, 324 F.Supp. 470 (N.D.Ill.1971); Noel v. United Aircraft Corp., 219 F.Supp. 556 (D.Del.1963), aff’d in pertinent part, 342 F.2d 232 (3d Cir.1965); Ambriz v. Petrolane Ltd., 49 Cal.2d 470, 319 P.2d 1 (1957), reversing 312 P.2d 11, 17 (4th Dist.Ct.App.1957). As with the issue of foreseeability, the issue of costs, social utility, and potential practical remedies can only be decided after a full factual presentation and analysis of applicable law. (b) Duty to Warn and Proximate Cause In addition to showing that warnings (or other safety features) were required by the standard of reasonable care and that defendants failed to give such warnings or failed to give them in an adequate manner, plaintiffs must establish a causal connection. They must show (1) that defendants’ failure to warn was a “cause in fact” of their injuries — i.e., the warnings might have averted the particular accident— and (2) that defendants’ failure to warn was a “proximate cause” of their injuries — i.e., intervening events, remoteness or general policy considerations do not prevent a finding of liability. See, e.g., Green, The Causal Relation Issue in Negligence Law, 60 Mich.L.Rev. 543, 548-569 (1962); 2 Harper & James, The Law of Torts §§ 20.1-.6 at 1108-1161 (1956) and Supplement at 92-104 (1968). But cf. Harper and James, id. Supplement at 93 (“the dichotomy is not a clear one”). Existence of the I.M.E. safety program and the possibility of intervening acts by others are relevant to the question of defendants’ liability for failure to warn, but they do not entitle defendants at this stage to a judgment as a matter of law. The practice of the explosives industry of supplying warnings to customers and users through notices printed on and inserted in packages of blasting caps has already been the subject of litigation. In Eek v. E. I. Du Pont De Nemours & Co., 393 F.2d 197 (7th Cir.1968), the Seventh Circuit held that whether such warnings had adequately served notice on an injured workman, “either personally or vicariously, raised an issue of fact which the court should have submitted to the jury.” 393 F.2d 197, 201. The adequacy of printed warnings and the I.M.E. safety program is even less clear-cut in this case, where the manufacturers cannot claim that children, in contrast to workmen using blasting caps, are aware of risks generally known in the trade. Cf. Hopkins v. E. I. Du Pont De Nemours & Co., 199 F.2d 930, 933 (3d Cir.1952), judgment reversed on basis of Pennsylvania law, 212 F.2d 623 (3d Cir.1954); Canifax v. Hercules Powder Co., 237 Cal.App.2d 44, 54-55, 46 Cal.Rptr. 552, 559 (3d Dist.1965). The defendants’ contention that warnings on the caps might have been ineffective had they been given, refers to problems of proof which clearly cannot be resolved prior to a full factual presentation. See 2 Harper & James, The Law of Torts, § 20.2 at 1113-14 (1956) and Supplement at 94-95 (1968); Green, The Causal Relation Issue In Negligence Law, 60 Mich. L.Rev. 543, 559-60 (1962); cf. Jacobs v. Technical Chemical Co., 472 S.W.2d 191, 196-200 (Tex.Ct.Civ.App.1971); Haft v. Lone Palm Hotel, 3 Cal.3d 756, 768-69, 91 Cal.Rptr. 745, 752, 478 P.2d 465, 472 (1970). The general rule on intervening acts and proximate cause includes the element of foreseeability: an intervening act by a third person (even if negligent) relieves the original negligent actor from liability only if “the subsequent wrongdoer’s act could not have been anticipated by the first actor in the exercise of due care.” Boeing Airplane Co. v. Brown, 291 F.2d 310, 317-18 (9th Cir. 1961); see also Rest.2d Torts § 447(a) (1965); 2 Harper & James, The Law of Torts, § 28.10 at 1555, § 20.5 at 1141-46 (1956). In many cases the defendant’s negligence rests precisely on his failure to guard against the risks of foreseeable misconduct by others, and the occurrence of such misconduct, “whether innocent, negligent, intentionally tortious, or criminal does not prevent the actor from being liable for harm caused thereby.” Rest.2d Torts § 449 (1965). Alternatively stated, “[t]he happening of the very event the likelihood of which makes the actor’s conduct negligent cannot relieve him from liability.” Rest.2d Torts § 449, comment b (1965); cf. Petition of Kinsman Transit Co., 338 F.2d 708, 723-24 (2d Cir. 1964), cert. denied sub nom. Continental Grain Co. v. City of Buffalo, 380 U.S. 944, 85 S.Ct. 1026, 13 L.Ed.2d 963 (1965). A typical application of this principle is found in numerous eases holding that trespassing, tampering, and other misconduct by children, particularly in relation to dangerous instruments and machinery, is a foreseeable risk whose occurrence does not insulate a defendant who has failed to provide reasonable safeguards. See 2 Harper & James, The Law of Torts, § 20.5 at 1144 n. 34 (1956) and Supplement at 100 (1958); Rest.2d Torts § 449, Appendix at 245-57 (1966). Even if it were determined that such acts, or certain kinds of acts, constituted superseding causes, it would still be a question for the jury (assuming sufficiency of the plaintiffs’ evidence) as to whether they actually occurred. See McLaughlin v. Mine Safety Appliances, 11 N.Y.2d 62, 71-72, 226 N. Y.S.2d 407, 413-14, 181 N.E.2d 430, 435 (1962). (2) Strict Liability A duty to warn may be imposed on a manufacturer under strict liability principles if without a warning his product would be “in a defective condition unreasonably dangerous to the user or consumer.” Rest.2d Torts § 402A and comment j (1965). Whether a product is “defective” or “unreasonably dangerous” depends on the same considerations respecting harm already discussed in the context of negligence: foreseeability, seriousness and cost of preventing. Under strict liability principles, however, they are applied in a somewhat different manner. The plaintiff does not have to identify and prove a particular failure to exercise reasonable care on the part of the manufacturer, nor can the manufacturer assert in defense that the product’s design or manufacture was carried out with reasonable care. See, e. g., O’Keefe v. Boeing Co., 335 F.Supp. 1104, 1118-19, 1132 (S.D.N.Y.1971); Cunningham v. MacNeal Memorial Hospital, 47 Ill.2d 443, 453-54, 266 N.E.2d 897, 902 (1970); Rest.2d Torts § 402A(a) (1965). There are two reasons for imposing strict liability on manufacturers. They may be summarized by the phrases “incentive” and “risk allocation.” A manufacturer is in the best position to discover defects or dangers in his product and to guard against them through appropriate design, manufacturing and distribution safeguards, inspection and warnings. See, e. g., Vandermark v. Ford Motor Co., 61 Cal.2d 256, 260-63, 37 Cal.Rptr. 896, 898-900, 391 P.2d 168, 170-72 (1964); Escola v. Coca-Cola Bottling Co. of Fresno, 24 Cal.2d 453, 461, 150 P.2d 436, 440-41 (1944) (Traynor, J., concurring); James, General Products — Should Manufacturers Be Liable Without Negligence?, 24 Tenn.L.Rev. 923 (1957). A rigorous rule of liability with enhanced possibilities of large recoveries is an “incentive” to maximize safe design or a “deterrence” to dangerous design, manufacture, and distribution. See, e. g., Vandermark v. Ford Motor Co., 61 Cal. 2d 256, 260-63, 37 Cal.Rptr. 896, 898-900, 391 P.2d 168, 170-72 (1964); Katz, The Function of Tort Liability in Technology Assessment, 38 U.Cinn.L.Rev. 587, 607-08, 631-36 (1969). The fact that the safety practices of entire industries have been held to be below the standard of reasonable care indicates the need for broad safety incentives. See Marsh Wood Products Co. v. Babcock and Wilcox Co., 207 Wis. 209, 218-19, 240 N.W. 392, 396 (1932); The T. J. Hooper, 60 F.2d 737, 740 (2d Cir. 1932); cf. Canifax v. Hercules Powder Co., 237 Cal.App.2d 44, 55, 46 Cal.Rptr. 552, 559 (3d Dist.1965); Katz, The Function of Tort Liability in Technology Assessment, 38 U.Cinn.L.Rev. 587, 631-36 (1969). A second approach has been-variously expressed as “loss distribution,” “risk allocation,” or “enterprise liability.” Regardless of safety measures taken by manufacturers and distributors, accidents and injuries will inevitably occur which can be fairly said to have been wholly or partly caused by some defective characteristic of the product involved. Accidents and injuries, in this view, are seen as an inevitable and statistically foreseeable “cost” of the product’s consumption or use. See, e. g., Greenman v. Yuba Power Products, Inc., 59 Cal.2d 57, 63-64, 27 Cal.Rptr. 697, 701, 377 P.2d 897, 901 (1962). The policy question of who should bear this cost has already been resolved in the great majority of jurisdictions which have adopted the principle of strict tort liability for manufacturers and suppliers, or its equivalent, implied warranty without privity. See, for compilations of jurisdictions which have adopted these doctrines, Prosser, The Fall of the Citadel (Strict Liability to the Consumer), 50 Minn.L.Rev. 791, 794-99 (1966); 2 Frumer & Friedman, Products Liability, § 16A [3] (1970 rev.). These jurisdictions include seven of the ten states in which plaintiffs’ injuries occurred, three of the four states in which the manufacturers have their principal places of business, and the state of New York in which the trade association is located and in which the action has been brought. Strict liability concepts do not require the manufacturer to produce a product incapable of doing harm; the very utility of many products, such as knives and automobiles, presupposes characteristics which can inflict harm. A “defect” must “cause” the harm. [A] plaintiff must trace his injury to a quality or condition of the product which was unreasonably dangerous either for a use to which the product would ordinarily be put, or for some special use which was brought to the attention of the defendant. These are the risks and losses which may fairly be regarded as typical of the enterprise and so fairly allocable to it. James, General Products — Should Manufacturers Be Liable Without Negligence? 24 Tenn.L.Rev. 923, 927 (1957) (citation omitted). It is important to note that there is no sharp boundary between foreseeability — i. e., probability of harm — under negligence and under strict liability principles. On the contrary, there has been a continual interplay between the two doctrines. See, for an example of strict liability as influenced by foreseeability under negligence principles, Davis v. Wyeth Laboratories, Inc., 399 F.2d 121, 129-30 (9th Cir. 1968) citing Wright v. Carter Products, Inc., 244 F.2d 53, 56, 58 (2d Cir. 1957); for the converse example see the broad concept of foreseeability adopted under negligence principles in Larsen v. General Motors Corp., 391 F.2d 495, 501-03 (8th Cir. 1968). Reduction of the threshold probability required before a defendant-manufacturer can be held liable in either negligence or strict liability has resulted from the abandonment of rigid categorical judgments about what kinds of uses and users are foreseeable, and from an increased willingness to submit such issues to juries where the determination “depends on policy values underlying the ‘common affairs of life.’ ” Passwaters v. General Motors Corp., 454 F.2d 1270, 1275 n. 5 at 1276 (8th Cir. 1972). See also Noel, Defective Products: Abnormal Use, Contributory Negligence, and Assumption of Risk, 25 Vand.L.Rev. 93, 128 (1972). In enterprise liability terms, what is important is “the foreseeability of the kinds of risks which the enterprise is likely to create” as distinguished from the negligence standard’s focus on foreseeably unreasonablé risks of specific conduct in particular circumstances. James, General Products — Should Manufacturers Be Liable Without Negligence?, 24 Tenn.L.Rev. 923, 925 (1957). Scope of possible liability is measured not by what “can and should reasonably be avoided” (though it may include such risks) but rather “the more or less inevitable toll of a lawful enterprise.” 2 Harper & James, The Law of Torts § 26.7 at 1377 (1956). As in the areas of workmen’s compensation and (in some jurisdictions) respondeat superior, the enterprise’s liability extends to “the harm . . . typical for [the enterprise’s] activities, and thus calculable and reasonably insurable.” Ehrenzweig, Negligence Without Fault, 54 Calif.L. Rev. 1422, 1457 (1966). Courts have used both “incentive” and “risk allocation” theories in applying strict liability. In a case holding a drug manufacturer liable for failure to warn users of the statistically small but qualitatively severe danger of a polio vaccine, the Ninth Circuit emphasized the fact of the manufacturer’s actual knowledge of the risks involved. While the manufacturer was immune from liability during an initial period when “there was no known or foreseeable risk involved in taking [the drug],” “after further experience, the danger became apparent [and] a duty to warn attached.” Davis v. Wyeth Laboratories, Inc., 399 F.2d 121, 129 (9th Cir. 1968). See also Basko v. Sterling Drug Co., Inc., 416 F.2d 417, 426 (2d Cir. 1969). In cases where manufacturers have more experience, more information, and more control over the risky properties of their products than do drug manufacturers, courts have applied/ a broader concept of foreseeability which approaches the enterprise liability rationale. See generally Noel, Defective Products: Extension of Strict Liability to Bystanders, 38 Tenn.L.Rev. 1, 7-10 (1970) and cases cited therein. A number of jurisdictions, including California, Texas, Indiana, New Jersey, Connecticut, Arizona, Michigan and New York have extended strict liability beyond its limitation in the Restatement to “users and consumers” (Rest.2d Torts § 402A and comment o on Caveat (1965)) to include third parties and “bystanders” injured by products such as automobiles, shotguns, and power lawnmowers. See Elmore v. American Motors Corp., 70 Cal.2d 578, 75 Cal.Rptr. 652, 451 P.2d 84 (1969); Darryl v. Ford Motor Co., 440 S.W.2d 630 (Tex.1969); Sills v. Massey-Ferguson, Inc., 296 F. Supp. 776 (N.D.Ind.1969); Lamendola v. Mizell, 115 N.J.Super. 514, 280 A.2d 241 (1970); Mitchell v. Miller, 26 Conn.Super. 142, 214 A.2d 694 (1965); Caruth v. Mariani, 11 Ariz.App. 188, 463 P.2d 83 (1970); Piercefield v. Remington Arms, 375 Mich. 85, 133 N.W.2d 129 (1965); Codling v. Paglia, 38 A.D.2d 154, 327 N.Y.S.2d 978 (3d Dep’t 1972). These courts reason that defects in, for example, automobiles pose a thoroughly foreseeable risk to other persons on or near the road, and that the policies underlying strict liability — control of the risk and spreading of loss — are applicable regardless of the “user or consumer” limitation. See, e. g., Elmore v. American Motors Corp., 70 Cal.2d 578, 586, 75 Cal.Rptr. 652, 657, 451 P.2d 84, 88-89 (1969); cf. for discussion of enterprise liability and products other than automobiles: Sills v. Massey-Ferguson, Inc., 296 F.Supp. 776, 781 (N.D.Ind.1969) (power lawnmower); Klimas v. International Telephone and Telegraph Corp., 297 F.Supp. 937, 941-42 (D.R.I.1969) (electrical fuse). As in the case of negligence, the greater the product’s dangers when defects are present, the less the power of the court to preclude recovery by foreclosing a jury judgment of culpability. Davis v. Wyeth Laboratories, Inc., 399 F.2d 121, 129-30 (9th Cir. 1968). Similarly, where tampering by children is involved, negligence’s tenderness towards youth is reflected in a reluctance to dismiss a strict liability claim. Thomas v. General Motors Corp., 13 Cal.App.3d 81, 91 Cal.Rptr. 301 (4th Dist. 1970). If the standard of strict liability is found applicable to the absence of warnings on the caps, the range of intervening acts which will insulate the defendants from liability will be even narrower than under negligence principles. See Rest.2d Torts § 402A, comment n (1965); 2 Frumer & Friedman, Products Liability § 16A [5] [f]. However that range of intervening acts is defined under the laws of the various states, it will remain a jury question as to whether they occurred. See Sills v. Massey-Ferguson, Inc., 296 F.Supp. 776, 782 (N.D.Ind.1969). D. Joint Liability The central question raised by defendants’ motion is whether the defendants can be held responsible as a group under any theory of joint liability for injuries arising out of their individual manufacture of blasting caps. Joint tort liability is not limited to a narrow set of relationships and circumstances. It has been imposed in a wide range of situations, requiring varying standards of care, in which defendants cooperate in various degrees, enter into business and property relationships, and undertake to supply goods for public consumption. Developments in negligence and strict tort liability have imposed extensive duties on manufacturers to guard against a broad spectrum of risks with regard to the general population. The reasoning underlying current policy justifies the extension of established doctrines of joint tort liability to the area of industry-wide cooperation in product manufacture and design. (1) The Elements of Joint Liability Joint liability has historically been imposed in four distinguishable kinds of situations: (1) the actors knowingly join in the performance of the tortious act or acts; (2) the actors fail to perform a common duty owed to the plaintiff; (3) there is a special relationship between the parties (e. g., master and servant or joint entrepreneurs); (4) although there is no concerted action nevertheless the independent acts of several actors concur to produce indivisible harmful consequences. 1 Harper & James, The Law of Torts § 10.1 at 697-98 (1956). See also Prosser, Joint Torts and Several Liability, 25 Calif.L.Rev. 413, 429 et seq. (1937). These categories reflect three overlapping but distinguishable problems with which the law of joint liability has been concerned. The first is the problem of joint or group control of risk: the need to deter hazardous behavior by groups or multiple defendants as well as by individuals. The second is the problem of enterprise liability: the policy of assigning the foreseeable costs of an activity to those in the most strategic position to reduce them. The third is the problem of fairness with respect to burden of proof: the desire to avoid denying recovery to an innocent injured plaintiff because proof of causation may be within defendants’ control or entirely unavailable. The complaint and defendants’ motion to dismiss raise all three problems for consideration. (2) Joint Control of Risk The problem of joint control of risk was early posed in a case of group assault. In imposing joint liability, the court reasoned that “ . . . [with] all coming to do an unlawful act, and of one party, the act of one is the act of all. . . . ” See Sir John Heydon’s Case, 11 Co.Rep. 5, 77 Eng.Rep. 1150 (1613), and other English eases cited in Prosser, Law of Torts § 46 at 291 (4th ed. 1971). Even in its earliest form the doctrine of joint liability for concerted action contained all the elements necessary for its future development: (1) causing harm (2) by cooperative or concerted activities (3) which violated a legal standard of care. American courts have imposed joint liability for concerted action in cases involving a complex interaction of the three elements of the doctrine. “Cooperation” or “concert” has been found in various business and property relationships, group activities such as automobile racing, cooperative efforts in medical care or railroad work, and concurrent water pollution. “Express agreement is not necessary; all that is required is that there shall be a common design or understanding.” Prosser, Joint Torts and Several Liability, 25 Cal.L.Rev. 413, 429-30 (1937). The standard of care to which defendants have been jointly held has ranged from assault and reckless driving to negligence in building maintenance, brush burning, water pollution, and manufacture of explosives. See, e. g., Simmons v. Everson, 124 N.Y. 319, 25 N.E. 911 (1891) (collapsed wall supported by interlocking walls); Prussak v. Hutton, 30 App.Div. 66, 51 N.Y.S. 761 (3d Dep’t 1898) (powder house used and maintained by several defendants); Troop v. Dew, 150 Ark. 560, 234 S.W. 992 (1921) (defendant contractors breaking fences allowing cattle to enter) ; Hanrahan v. Cochran, 12 App.Div. 91, 42 N.Y.S. 1031 (4th Dep’t 1896) (racing horses); Bierczynski v. Rogers, Del., 239 A.2d 218 (1968) (racing cars); Sprinkle v. Lemley, 243 Or. 521, 414 P. 2d 797 (1966) (doctors treating same patient); Michigan Millers Mut. Fire Ins. Co. v. Oregon-Washington R. & Nav. Co., 32 Wash.2d 256, 201 P.2d 207 (1948) (railroads burning brush); Moses v. Town of Morgantown, 192 N.C. 102, 133 S.E. 421 (1926) (independent discharging of refuse into stream); Thompson v. Johnson, 180 F.2d 431 (5th Cir. 1950) (assault by several individuals) ; Dement v. Olin-Mathieson Chemical Corp., 282 F.2d 76 (5th Cir. 1960) (manufacturers of components). These diverse eases impose joint liability on groups whose actions create unreasonable hazards of risks of harm, even though only one member of the group may have been the “direct” or physical cause of the injury. Where courts perceive a clear joint control of risk — typically the racing and assault cases, as well as those involving common duties or joint enterprise — the issue of who “caused” the injury is distinctly secondary to the fact that the group engaged in joint hazardous conduct. This rationale was recognized in the nineteenth century. In a case involving a horse race in a crowded street, a New York court noted that the collision was “not willful or intentional on the part of the defendants,” but it upheld a jury determination that the negligent racing of the defendants was the joint cause of injury. Hanrahan v. Cochran, 12 App. Div. 91, 94, 42 N.Y.S. 1031, 1032-33 (4th Dep’t 1896). Imposing liability on the defendant not involved in the actual collision, the court stated that “these defendants were acting together and in concert in this race. It was the race that created the condition that resulted in the accident.” 12 App.Div. at 95, 42 N.Y.S. at 1033. By participating in a joint creation of negligent risk, both defendants were held liable for the consequences. See, for a modern application of this rule to automobile racing, Lemons v. Kelly, 239 Or. 354, 360-61, 397 P. 2d 784, 787 (1964), and Annot., 13 A.L.R.3d 431 (1967) (collecting cases). Analogous language focusing on the joint creation of risk can be found in the “common duty” cases, as when several defendants neglect to maintain a party wall. Simmons v. Everson, 124 N.Y. 319, 25 N.E. 911 (1891). Joint control of risk can also arise through business relations or joint enterprise. .Thus a New York court found that the owner and lessee of a powder magazine, as well as the purchaser of the powder, all “participated in the maintenance of the powder house” and hence were jointly liable for damages caused by explosion. Prussak v. Hutton, 30 App.Div. 66, 67, 51 N.Y.S. 761, 763 (3d Dep’t 1898). See also Lindsay v. Acme Cement Plaster Co., 220 Mich. 367, 190 N.W. 275 (1922) (two defendants under a duty to keep track in repairs); Walton, Witten & Graham Co. v. Miller’s Adm’x, 109 Va. 210, 63 S.E. 458 (1909) (employer and contractor both under duty to warn employee as to blasting); Troop v. Dew, 150 Ark. 560, 234 S.W. 992 (1921) (independent contractors both under duty to repair fences). The opinions frequently refer to the defendants’ violations of a common duty of care not only in terms of joint control of risk, but also as concurrent causes which combine to produce injury. See, e. g., Walton, Wit-ten & Graham Co. v. Miller’s Adm’x, 109 Va. 210, 213-14, 63 S.E. 458, 460 (1909). Defendants argue that their participation in the I.M.E. safety program, and their cooperative or parallel activities regarding the safety features of blasting caps do not give them joint control over the risks of injury for purposes of tort liability. Joint control of risk and consequent joint responsibility arises, in their view, only when manufacturers enter into a conspiracy to commit intentional harm, or into a partnership or joint venture. The key to a joint venture, they assert, is an agreement to share profits and to pursue a limited number of business objectives over a short period of time. Since the defendants’ membership in their trade association involves neither profit-sharing nor a limited time-span, they contend that no joint responsibility arises from the association and its members’ activities. The problem with this argument is that the elements of joint control of risk do not coincide with those in the formal doctrine of joint venture. The distinction was the basis for decision in Connor v. Great Western Savings & Loan Ass’n, 69 Cal.2d 850, 73 Cal.Rptr. 369, 447 P.2d 609 (1968). The court found that a savings bank (Great Western) and a housing developer (Conejo) had, as a matter of practical economics, combined their property, skill, and knowledge to carry out the tract development, that each shared in the control of the development, that each anticipated receiving substantial profits therefrom, and that they cooperated with each other in the development. 69 Cal.2d 850, 863, 73 Cal.Rptr. 369, 375, 447 P.2d 609, 615 Despite this extensive cooperation and shared control of the venture the court found that there is no evidence of a community or joint interest in the undertaking. Great Western participated as a buyer and seller of land and lender of funds, and Conejo participated as a builder and seller of homes. Although the profits of each were dependent on the overall success of the development, neither was to share in the profits or the losses that the other might realize or suffer. Id. Applying the rule that [A] joint venture exists when there is “an agreement between the parties under which they have ... a joint interest, in a common business undertaking, and understanding as to the sharing of profits and losses, and a right of joint control.” Id. (citations omitted), the court declined to hold the bank vicariously liable as a joint venturer for the negligence of the developer. The court did find the bank liable for its own negligence in exercising what in practical effect was its joint control of the venture. In undertaking these relationships [with the developer] Great Western [the bank] became much more than a lender content to lend money at interest on the security of real property. It became an active participant in a home construction enterprise. It had the right to exercise extensive control of the enterprise. Its financing, which made the enterprise possible, took on ramifications beyond the domain of the usual money lender. 69 Cal.2d 850, 864, 73 Cal.Rptr. 369, 376, 447 P.2d 608, 616. The bank, it held, should have realized that the thinly capitalized builder would be under great pressure to put up shoddy housing. The lesson is clear that joint control of risk can exist among actors who are not bound in a profit-sharing joint venture. This point is thoroughly confirmed by cases imposing joint liability on “joint enterprises,” which are distinguished from “joint ventures” as being “non profit undertaking [s] for the mutual benefit or pleasure of the parties” (Connor v. Great Western Savings & Loan Ass’n, 69 Cal.2d 850, 863-64 n. 6, 73 Cal.Rptr. 369, 376 n. 6, 447 P.2d 609, 616 n. 6 (1968)) and on which joint liability is imposed because of the parties’ effective joint control of the risk. See Prosser, Law of Torts § 72 at 475-80 (4th ed. 1971). Joint control may be shown in one of three ways. First, plaintiffs can prove the existence of an explicit agreement and joint action among the defendants with regard to warnings and other safety features — the classic “concert of action.” Second, plaintiffs can submit evidence of defendants’ parallel behavior sufficient to support an inference of tacit agreement or coopera