In this appeal, plaintiff-appellant Monica Santiago challenges the district court's entry of summary judgment against her and in favor of defendants-appellees.1 In so doing, plaintiff advances three arguments: (1) the legal issues in this appeal should be certified to the Massachusetts Supreme Judicial Court ("SJC"); (2) the district court erred in rejecting plaintiff's market share liability argument; and (3) the court erred in rejecting plaintiff's concert of action claim. After carefully reviewing each of plaintiff's arguments, we affirm.

Plaintiff was born on November 9, 1972. From the time of her birth until 1978, she and her family resided at 20 Leston Street in Boston. Plaintiff alleges that, during her period of residence, she ingested lead paint that had been applied in layers to the walls and woodwork of her home at various times between 1917, the year of the building's construction, and 1970. The evidence reveals that plaintiff's blood had highly elevated levels of lead by the time plaintiff was one year of age, that the lead reached emergency levels by July 1976, and that, as a consequence, plaintiff had to undergo chelation therapy2 in order to remove the lead from her body. Although plaintiff's early development appeared to progress normally, she has been diagnosed with a hyperactivity-attention disorder and motor skill difficulties which her medical experts attribute to lead poisoning.

Plaintiff initiated this action in November 1987, contending that defendants, or their predecessors in interest, manufactured and marketed all, or virtually all, of the white lead used in the lead paints sold in the United States between 1917 and 1970. Her complaint set forth claims of negligence, breach of warranty, and concert of action. Jurisdiction was premised upon diversity of citizenship. See 28 U.S.C. Sec. 1332.

Plaintiff could not and cannot identify either which, if any, of the defendants are the source of the lead she ingested or when the alleged injury-causing paint may have been applied to the walls and woodwork of her childhood home.3 She has, however, introduced (1) evidence in the form of expert testimony that lead paint "was at minimum a substantial contributing factor of her lead poisoning;" (2) evidence demonstrating that all of the defendants produced white lead for significant portions of the period between 1917 and 1970; (3) evidence that almost all of the white lead produced for paint between 1917 and 1970 was manufactured by defendants; and (4) evidence that, between 1930 and 1945, all of the defendants, as members of a trade association known as the Lead Industries Association ("LIA"), "simultaneously coordinat[ed] promotional campaigns to increase white lead consumption in paint and ... work[ed] to neutralize the growing public concern about lead paint poisoning." On the basis of this evidence, plaintiff sought to dispense with the identification requirement and hold defendants liable under a market share theory. Plaintiff further argued that defendants were liable for her injuries because of their concerted marketing actions as members of the LIA.

By memorandum and order dated January 13, 1992, the district court rejected plaintiff's market share claim as a matter of Massachusetts law. In so doing, the court ruled that even if the SJC would recognize market share liability under some scenario, it would not do so if presented with the undisputed facts of this case. See generally Santiago v. Sherwin-Williams Co., 782 F. Supp. 186 (D.Mass.1992). By memorandum and order dated July 2, 1992, the court further ruled that plaintiff's concert of action claim failed as a matter of Massachusetts law because plaintiff could not identify which of the defendants actually had committed the tort. See generally Santiago v. Sherwin-Williams Co., 794 F. Supp. 29 (D.Mass.1992). It is from these rulings that plaintiff now appeals.

As an initial matter, plaintiff has requested that we certify to the SJC questions regarding the viability of market share liability and concert of action as theories of recovery in light of the facts of this case. We note that plaintiff first requested certification in this court, and explicitly stated her opposition to certification at the district court level. Now, having lost below, plaintiff has reversed her position. Unsurprisingly, defendants oppose plaintiff's certification request.

For reasons that are largely self-explanatory, we have held that "one who chooses to litigate [her] state action in the federal forum (as plaintiff did here) must ordinarily accept the federal court's reasonable interpretation of extant state law rather than seeking extensions via the certification process." Croteau v. Olin Corp., 884 F.2d 45, 46 (1st Cir.1989); see also 17A Charles A. Wright, Arthur R. Miller, and Edward H. Cooper, Federal Practice and Procedure Sec. 4248, 176 (2d ed. 1988) (courts "should be slow to honor a request for certification from a party who chose to invoke federal jurisdiction"). The concerns about fundamental fairness and judicial economy that animate this general rule make us considerably less inclined to depart from it when the plaintiff did not request certification before the district court. See Croteau, 884 F.2d at 46.

Here, as will be demonstrated below, the district court's interpretation of Massachusetts law was eminently reasonable. Furthermore, plaintiff, after initially deciding to eschew her prerogative to file this action in state court, actively made her opposition to certification known to the district court. In light of these facts, and given the further fact that it has been over five years since these federal proceedings were initiated, it would be extremely unfair to defendants if we were to allow plaintiff to relitigate the issues at the heart of this lawsuit. Accordingly, plaintiff's request for certification is denied.4

Having dispensed with plaintiff's certification request, we proceed to delineate the parameters of our examination. Summary judgment allows courts to "pierce the boilerplate of the pleadings and assay the parties' proof in order to determine whether trial is actually required." Wynne v. Tufts Univ. Sch. of Medicine, 976 F.2d 791, 794 (1st Cir.1992), cert. denied, --- U.S. ----, 113 S. Ct. 1845, 123 L. Ed. 2d 470 (1993). It should be granted when "the pleadings, depositions, answers to interrogatories, and admissions on file, together with the affidavits, if any, show that there is no genuine issue as to any material fact and that the moving party is entitled to judgment as a matter of law." Fed.R.Civ.P. 56(c).

A fact is only material if it has "the potential to affect the outcome of the suit under the applicable law." Nereida-Gonzalez v. Tirado-Delgado, 990 F.2d 701, 703 (1st Cir.1993). However, our reading of the facts, as derived from the record, is always done " 'in the light most amiable to the nonmovant....' " Lawrence v. Northrop Corp., 980 F.2d 66, 68 (1st Cir.1992) (quoting Garside v. Osco Drug, Inc., 895 F.2d 46, 48 (1st Cir.1990)). This includes "indulg[ing] all reasonable inferences" in the nonmovant's favor. Id.

Our review of a summary judgment ruling is plenary. Garside, 895 F.2d at 48. Furthermore, we are not limited to the reasoning employed by the district court; instead, we may "affirm the entry of summary judgment on any independently sufficient ground made manifest by the record." United States v. One Parcel of Real Property, 960 F.2d 200, 204 (1st Cir.1992).

In addition to examining the facts, a court passing on a summary judgment motion or reviewing a summary judgment determination must, of course, consider the applicable law. When a plaintiff invokes diversity jurisdiction to bring a state law claim in federal court, this survey is somewhat circumscribed, for it is settled that, in ordinary circumstances, a plaintiff who "selects a federal forum in preference to an available state forum may not expect the federal court to steer state law into unprecedented configurations." Martel v. Stafford, 992 F.2d 1244, 1247 (1st Cir.1993); see also Ryan v. Royal Ins. Co., 916 F.2d 731, 744 (1st Cir.1990) (rejecting a diversity plaintiff's attempt to stretch New York law to new frontiers without providing a "well-plotted roadmap showing an avenue of relief that the state's highest court would likely follow"); Porter v. Nutter, 913 F.2d 37, 41 (1st Cir.1990) (plaintiff who seeks out a federal venue in a diversity action should expect "unadventurous" interpretations of state law). Mindful of these strictures, we turn to plaintiff's claims.

Plaintiff argues that the district court erred in granting defendants summary judgment on her claim for market share liability. In so doing, she concedes that the SJC has never explicitly endorsed a market share liability theory of recovery, and further recognizes that the court rejected a certain species of market share liability advanced by plaintiffs in a DES class action. See Payton v. Abbott Labs., 386 Mass. 540, 437 N.E.2d 171, 188-90 (1982).5 Nonetheless, plaintiff asserts that certain dicta in Payton indicate that her claim would be approved by the SJC.6 We cannot agree.

As the SJC has noted, "[i]dentification of the party responsible for causing injury to another is a longstanding prerequisite to a successful negligence action." Payton, 437 N.E.2d at 188. However, some courts, cognizant of the modern industrial reality of fungible goods which may harm consumers but which cannot be traced to specific producers, have relaxed this identification requirement in certain negligence and product liability cases. In these cases, the courts have allowed plaintiffs who are unable to identify the particular defendant who actually manufactured the harm-causing product to pursue their claims so long as they are able to prove both that the product caused the harm and that the defendants were market suppliers at the time plaintiff had her harmful encounter with the product. See, e.g., Sindell v. Abbott Labs., 26 Cal. 3d 588, 163 Cal. Rptr. 132, 144-46, 607 P.2d 924, 936-38, cert. denied, 449 U.S. 912, 101 S. Ct. 285, 66 L. Ed. 2d 140 (1980). If a plaintiff prevails in such a case, courts typically have limited each defendant's liability to that portion of the plaintiff's judgment which reflects the share of the market supplied by the defendant at the time of said encounter. See, e.g., id., 163 Cal.Rptr. at 145, 607 P.2d at 937. Market share liability has most often been recognized in the context of DES cases. See, e.g., McCormack v. Abbott Labs., 617 F. Supp. 1521 (D.Mass.1985); McElhaney v. Eli Lilly & Co., 564 F. Supp. 265 (D.S.D.1983); Conley v. Boyle Drug Co., 570 So. 2d 275 (Fla.1990); Hymowitz v. Eli Lilly & Co., 73 N.Y.2d 487, 541 N.Y.S.2d 941, 539 N.E.2d 1069, cert. denied, 493 U.S. 944, 110 S. Ct. 350, 107 L. Ed. 2d 338 (1989); Martin v. Abbott Labs., 102 Wash.2d 581, 689 P.2d 368 (1984); Collins v. Eli Lilly & Co., 116 Wis. 2d 166, 342 N.W.2d 37, cert. denied, 469 U.S. 826, 105 S. Ct. 107, 83 L. Ed. 2d 51 (1984). But see Ray v. Cutter Labs., 754 F. Supp. 193 (M.D.Fla.1991) (product contained HIV virus); Morris v. Parke, Davis & Co., 667 F. Supp. 1332 (C.D.Cal.1987) (plaintiff harmed by DPT vaccine); Smith v. Cutter Biological, Inc., 72 Haw. 416, 823 P.2d 717 (1991) (product contained HIV virus).

As noted above, the SJC did have occasion to consider, by means of a certified question, the viability of one form of market share liability in a DES case. See Payton, 437 N.E.2d at 188-90. In Payton, plaintiffs argued for market share liability with two significant twists: (1) that they be allowed to proceed against and recover full damages from only six named DES manufacturers despite the fact that there was a larger number of potential tortfeasors, and (2) that defendants should be prohibited from presenting exculpatory proof. See id. at 188-89. The court rebuffed these arguments, holding that two articulated reasons for the identification requirement, (1) that wrongdoers be held liable only for the harm they have caused, and (2) that tortfeasors be separated from innocent actors, would be disserved by the adoption of plaintiffs' theory. Id. Accordingly, as we have stated, the SJC rejected plaintiffs' version of market share liability. Id. at 189.

We accept for the sake of argument plaintiff's assertions (1) that the SJC would, in some circumstances, relax the identification requirement and allow a plaintiff to recover under a market share theory; (2) that the SJC would recognize market share liability in the lead poisoning context; (3) that plaintiff has introduced sufficient evidence for a reasonable factfinder to infer that her injuries resulted from lead poisoning; (4) that lead paint was, as one of plaintiff's experts puts it, at least "a substantial contributing factor of her lead poisoning"; and (5) that defendants, who were mere bulk suppliers of white lead and did not manufacture or market the alleged injury-causing paint, could still be adjudged to have acted negligently towards plaintiff. Nonetheless, we believe that the SJC's professed interest in both holding wrongdoers liable only for the harm they have caused and in separating tortfeasors from innocent actors is fatal to plaintiff's claim.

Simply put, allowing plaintiff's market share claim to proceed despite plaintiff's inability to pinpoint with any degree of precision the time the injury-causing paint was applied to the house on Leston Street would significantly undermine both of the articulated reasons for the identification requirement. The record before us reflects that the layers of lead paint were applied to the house's walls at various undeterminable points in time between 1917 and 1970.7 It also indicates that defendants' contributions to the lead paint market varied significantly during this time period. Given these facts, it is difficult to discern the basis upon which any market share determination would be premised.8 At any rate, it is evident that the adoption of plaintiff's theory would not be consistent with the SJC's admonition that wrongdoers be held liable only for the harm they have caused.

Moreover, several of the defendants were not in the white lead pigment market at all for significant portions of the period between 1917 and 1970, and therefore may well not have been market suppliers at the time the injury-causing paint was applied to the walls of plaintiff's home. This, of course, raises a substantial possibility that these defendants not only could be held liable for more harm than they actually caused, but also could be held liable when they did not, in fact, cause any harm to plaintiff at all. Under plaintiff's theory, therefore, tortfeasors and innocent actors would not be adequately separated.

Finally, we note that the dicta relied upon by plaintiff indicates that a relaxation of the identification requirement to allow recovery against a negligent defendant would only be appropriate to the extent that the recovery represents "that portion of a plaintiff's damages which is represented by that defendant's contribution ... to the market in the relevant period of time." Id. at 190 (emphasis supplied). Here, as noted, plaintiff cannot identify with adequate specificity the relevant period of time. Thus, it appears that plaintiff's theory does not fall within even the vague parameters mentioned in the SJC's dicta.

In sum, allowing plaintiff to recover her full damages from the five named defendants despite her inability to specify the time of their negligence may well, on this record, do violence to the SJC's stated interest in ensuring that wrongdoers be held liable only for the harm they have caused. It also would create a substantial possibility that tortfeasors and innocent actors would be impermissibly intermingled. The SJC has made it abundantly clear that it would not countenance either result. Accordingly, mindful that federal courts sitting in diversity at a plaintiff's election ought not "steer state law into unprecedented configurations," see Martel, 992 F.2d at 1244, we affirm the district court's grant of summary judgment to defendants on plaintiff's market share claim.9

Finally, plaintiff contends that the district court erred in granting defendants summary judgment on her concert of action claim. Again, we cannot agree.

Plaintiff's concert of action claim is premised upon the theory of liability set forth in Section 876 of the Restatement (Second) of Torts (1977). In relevant part, Section 876 (entitled "Persons Acting in Concert") provides:

For harm resulting to a third person from the tortious conduct of another, one is subject to liability if he

(a) does a tortious act in concert with the other or pursuant to a common design with him, or

(b) knows that the other's conduct constitutes a breach of duty and gives substantial assistance or encouragement to the other so to conduct himself....

In isolated circumstances, Massachusetts courts have indicated their willingness to permit recovery under theories tracking the language of Section 876. E.g., Orszulak v. Bujnevicie, 355 Mass. 157, 243 N.E.2d 897, 898 (1969) ("Persons who race automobiles on a public way are liable in negligence for injuries caused by one of them."); Nelson v. Nason, 343 Mass. 220, 177 N.E.2d 887, 888 (1961) (similar).

In essence, plaintiff claims that, "in light of the substantial medical evidence of the unreasonable risk that [lead paint] posed to young children[,]" certain of defendants' actions as members of the LIA between 1930 and 1945 were tortious. Specifically, plaintiff points to defendants' "initiat[ion of] nationwide promotional campaigns, encourage[ment of] the use of white lead in house paint through extensive advertising, [attempts] to undermine the growing medical evidence of the danger of lead paint, and work[ ] to prevent the enactment of governmental regulations which would have restricted the use of white lead in painting buildings."10 What is utterly lacking from her presentation, however, is any evidence that these actions, during the fifteen year period she identifies, had any role in causing lead paint to be applied to the walls of her childhood home. Even if we assume that at least some of the lead paint consumed by plaintiff was applied to her home during the period of defendants' alleged concerted actions, there is no evidence that the application resulted from these actions, or that it would not have taken place in the absence of these actions. Cf. Roberts v. Southwick, 415 Mass. 465, 614 N.E.2d 659, 663 (1993) (endorsing instruction defining proximate cause as "that which, in continuous sequence, unbroken by a new cause, produces an event, and without which the event would not have occurred"). Thus, it is our view that the factfinder could only have based a causation finding on speculation or conjecture. Clearly, this is inappropriate under Massachusetts law. See Goffredo v. Mercedes-Benz Truck Co., 402 Mass. 97, 520 N.E.2d 1315, 1317-18 (1988); Gynan v. Jeep Corp., 13 Mass.App. 504, 434 N.E.2d 688, 691 (plaintiff "could not leave causation merely to speculation and conjecture"), review denied, 386 Mass. 1104, 440 N.E.2d 1177 (1982); see also W. Page Keeton et al., Prosser and Keeton on Torts Sec. 41, at 269 (5th ed. 1984) ("The plaintiff must introduce evidence which affords a reasonable basis for the conclusion that it is more likely than not that the conduct of the defendant was a cause in fact of the result. A mere possibility of such causation is not enough; and when the matter remains one of pure speculation or conjecture, or the probabilities are at best evenly balanced, it becomes the duty of the court to direct a verdict for the defendant.").

We acknowledge that the question of causation is generally for the factfinder. See Mullins v. Pine Manor College, 389 Mass. 47, 449 N.E.2d 331, 338 (1983). Where there is no evidence from which the factfinder, without speculating, can find causation, however, the case is appropriately kept from the jury. See Goffredo, 520 N.E.2d at 1318. We believe that this is such a case. Accordingly, we affirm the district court's decision to award defendants summary judgment on plaintiff's concert of action claim.11

Because certification to the SJC of the issues raised in this appeal would be inappropriate, plaintiff's request therefor is denied. Furthermore, because the district court correctly ruled that plaintiff's market share and concert of action claims fail as a matter of law, we affirm its granting of defendants' motions for summary judgment thereon.

Affirmed. Costs to appellees.