Full Opinion

*** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** Electronically Filed Supreme Court SCWC-XX-XXXXXXX 21-SEP-2026 10:11 AM Dkt. 56 OP IN THE SUPREME COURT OF THE STATE OF HAWAIʻI ---o0o--- ________________________________________________________________ GERARDO DENNIS PATRICKSON; BENIGNO TORRES HERNANDEZ; FERNANDO JIMENEZ ARIAS; ALIRIO MANUEL MENDEZ; and CARLOS HUMBERTO RIVERA, individually and on behalf of others similarly situated, Respondents/Plaintiffs-Appellants, vs. DOW CHEMICAL COMPANY and DEL MONTE FRESH PRODUCE N.A., INC., Petitioners/Defendants-Appellees, and DOLE FOOD COMPANY, INC.; DOLE FRESH FRUIT COMPANY; SHELL OIL COMPANY; OCCIDENTAL CHEMICAL CORPORATION (individually and as successor to Occidental Chemical Company and Occidental Chemical Agricultural Products, Inc., Hooker Chemical and Plastics, Occidental Chemical Company of Texas, and Best Fertilizer Company); STANDARD FRUIT COMPANY; STANDARD FRUIT AND STEAMSHIP COMPANY; DEL MONTE FRESH PRODUCE (HAWAI‘I), INC. (previously incorrectly named as Del Monte Fresh Produce Hawai‘i, Inc.), Respondents/Defendants-Appellees. ________________________________________________________________ SCWC-XX-XXXXXXX CERTIORARI TO THE INTERMEDIATE COURT OF APPEALS (CAAP-XX-XXXXXXX; CASE NO. 1CC071000047) SEPTEMBER 21, 2026 DEVENS, C.J., McKENNA, EDDINS, AND GINOZA, JJ., AND CIRCUIT JUDGE TOMASA, ASSIGNED BY REASON OF VACANCY *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** OPINION OF THE COURT BY McKENNA, J. I. Introduction This is the second appeal in this two-decade-old toxic tort case.1 The lawsuit was brought by Central and South American banana plantation workers alleging injuries caused by exposure to the pesticide dibromochloropropane (“DBCP”). Plaintiffs Gerardo Dennis Patrickson, Benigno Torres Hernandez, Alirio Manuel Mendez, Carlos Humberto Rivera, and Fernando Jimenez Arias (“Arias”)2 (collectively, the “Plaintiffs”) were previously employed by a subsidiary of Del Monte Fresh Produce N.A., Inc. (“Del Monte”), which used DBCP manufactured by Dow Chemical Company (“Dow”) in its banana plantations. In this appeal, the Intermediate Court of Appeals (“ICA”) made various rulings. Relevant to this certiorari proceeding, the ICA vacated the Circuit Court of the First Circuit’s (“circuit court”) orders granting: (1) Dow’s motion for summary judgment on Plaintiffs’ complaint; (2) Dow’s motion in limine excluding Plaintiffs’ expert witness, Michael J. DiBartolomeis, Jr. (“DiBartolomeis”); and (3) Del Monte’s joinders in Dow’s motions. 1 See Patrickson v. Dole Food Co., 137 Hawaiʻi 217, 368 P.3d 959 (2015) with respect to the first appeal. 2 Arias is referenced in the parties’ briefs as “Jimenez,” “Jimenez Arias,” and “Jimenez-Arias.” For consistency, we will refer to him as “Arias.” 2 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** On certiorari, Dow and Del Monte (collectively, the “Defendants”) challenge the ICA’s vacatur of summary judgment as to Arias, maintaining that the record does not reflect evidence of Arias’s exposure to DBCP. They further contend that DiBartolomeis’s expert opinions were properly excluded, rendering summary judgment appropriate as to Arias. Defendants also ask this court to determine if the ICA erroneously applied the wrong standard of review in vacating the circuit court’s order granting Dow’s motion in limine. For the reasons discussed below, we affirm the ICA and provide guidance on remand, including how to address causation in mass toxic torts cases, like this one, in which many people allege illness or injury caused by exposure to toxic substances. Thirty-five years ago, in Smith v. Cutter Biological, Inc., a Div. of Miles Inc., 72 Haw. 416, 823 P.2d 717 (1991), this court recognized that the traditional “substantial factor” causation test is unworkable in mass toxic tort cases: No longer can we apply traditional rules of negligence, such as those used in individual and low level negligence to mass tort cases, especially here, where we are dealing with a pharmaceutical industry that dispenses drugs on a wide scale that could cause massive injuries to the public, and where fungibility makes the strict requirements difficult to meet. The problem calls for adopting new rules of causation, for otherwise innocent plaintiffs would be left without a remedy. Smith, 72 Haw. at 428, 823 P.2d at 724 (emphasis added). In Smith, the plaintiff was unable to establish which of four manufacturers had caused his injury; for that circumstance, this 3 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** court adopted “the alternative market share theory of recovery.” Smith, 72 Haw. at 421, 823 P.2d at 721. Here, it is undisputed that Dow manufactured the DBCP that Del Monte’s subsidiary applied at the banana plantations where Plaintiffs were allegedly exposed. The alternative market share theory of recovery is therefore inapposite. The substantial factor test fares no better because it may still leave “otherwise innocent plaintiffs [] without a remedy.” Smith, 72 Haw. at 428, 823 P.2d at 724. And the “frequency, regularity, and proximity” test used in asbestos litigation, which Defendants urge this court to adopt, is merely a version of the substantial factor test. We therefore hold that the appropriate approach to causation in toxic tort cases is the one set out in comment g to section 26 of the Restatement (Third) of Torts (“Third Restatement”). See Restatement (Third) of Torts: Phys. & Emot. Harm § 26, cmt. g. In these types of cases, the Third Restatement evaluates causation based on (1) general causation, (2) specific causation, and (3) exposure to the agent: In toxic-substances cases, the causal inquiry is modified by the limits of and available forms of scientific evidence. That inquiry often must address whether the agent for which the actor is responsible is capable of causing the disease from which another suffers (known as general causation). In addition, the question whether the agent caused the specific plaintiff’s disease (known as specific causation) is confronted. See [Restatement (Third) of Torts] § 28, [cmt.] c(3) and c(4). In addition, a person’s exposure to the actor’s agent is another necessary aspect for factual cause to exist. See [Restatement (Third) of 4 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** Torts] § 28, [cmt.] c(2). Each of these distinct inquiries is a component of the factual-cause inquiry. Restatement (Third) of Torts: Phys. & Emot. Harm § 26, cmt. g. We reorder this causation test to (1) exposure to the agent, (2) general causation, and (3) specific causation. For if there was no exposure, it is not necessary to address general or specific causation. With this and the other guidance provided in this opinion, we affirm the ICA’s November 6, 2025 judgment on appeal. II. Background A. Factual background The following factual background is primarily derived from the deposition testimony of Arias and his wife, Vilma Julieta Graham Mastiel (“Mastiel”). Shortly after getting married, Arias worked as a quality fruit inspector for Bandeco from 1971 to 1973. Bandeco is a banana company based in Costa Rica and a subsidiary of Del Monte. Arias rotated on a weekly basis through eighteen banana farms, fifteen of which were owned by Bandeco, and worked up to seven days per week with little to no vacation days. He started his day by inspecting the quality of bananas arriving from the fields. The bananas were delivered to the patio of a packing facility before being taken inside, where Arias inspected them. 5 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** Each packing facility was located on the farm where the bananas were grown. Arias worked as part of a team of two or three quality inspectors assigned to a single packing facility. When an assignment required overnight stays, they slept in a house on the farm. At times, Arias remained on the farm for up to a week due to the volume of bananas requiring inspection. In addition to conducting quality inspections, Arias occasionally accepted invitations from the farm administrator to walk the fields to observe operations. This occurred every once in a while at each farm where he worked while employed by Bandeco. Field cutting typically concluded around midday, after which Arias and the other quality inspectors entered the fields. While in the fields, the administrator explained the farm’s management and operational practices. Arias never observed anyone applying pesticides during his employment, although he knew individuals who applied them without knowing what substances were being used. He neither applied DBCP,3 observed it being applied, nor handled it in any 3 For further discussion of DBCP, see Patrickson v. Dole Food Co., 251 F.3d 795 (9th Cir. 2001), Dole Food Co. v. Patrickson, 538 U.S. 468 (2003), Patrickson v. Dole Food Co., Inc., No. 30700, 2014 WL 895186 (App. Mar. 7, 2014) (mem. op.), and Patrickson, 137 Hawaiʻi 217, 368 P.3d 959. 6 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** way. DBCP is a powerful nematicide that was manufactured by Dow and used by Bandeco on its farms.4 When the field cutting ran late and the arrival of bananas was delayed, or during periods of heavy rain, Arias and the other quality inspectors went into warehouses where chemicals used on the farms were stored and slept on or near sacks containing those chemicals. They were unaware of any potential dangers from inhalation or whether the chemicals were poisonous. Although Arias could not recall the specific chemicals stored there, he knew they were chemicals because the warehouses were used to store substances applied to the banana crops. When the bananas arrived at the packing facility, or when it stopped raining, they exited the warehouses. Arias married Mastiel in 1968. From the time they were married until Mastiel’s first pregnancy in 1971, Arias and his wife attempted to have children, without success. During that 4 Del Monte confirmed in responses to Plaintiffs’ interrogatories that, between 1970 and 1973, Bandeco applied DBCP at its own banana farms at a rate of 4 or 5 [cubic centimeters] per injection, 6 [to] 8 injections per plant, [at a depth of 15 centimeters,] using a 50 [percent] diluted solution of DBCP. Each acre of banana plants had approximately [1,400 to 1,800] plants. There were two applications per year. This calculates to between 3.6 and 7.7 gallons per year of DBCP per cultivated acre of banana plants on Bandeco owned or operated farms, depending on the number of banana plants per acre and the number of [cubic centimeters] in each injection. “The DBCP was generally applied in two separate cycles lasting approximately two-months per cycle and was not applied monthly or more than two times per plant per year.” 7 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** period, they did not consult physicians due to financial constraints. Their first biological child was born in April 1971 and passed away later that year from an illness. They eventually had two children: one biological daughter born in April 1975, and a second daughter who they adopted. But between 1977 and 1983, Mastiel had three additional pregnancies that ended in miscarriages a few months after conception. Mastiel never used birth control or attempted to avoid pregnancy. Mastiel never received an explanation from her physicians regarding the cause of her miscarriages or any treatment for her pregnancy complications. Arias passed away in November 2023 during the course of these proceedings. C. Procedural background 1. Circuit court proceedings In their operative second amended complaint, Plaintiffs brought claims for negligence, conspiracy, and intentional tort against Dow and Del Monte, among others, and sought compensatory and punitive damages. Plaintiffs alleged that their health, welfare, and lives were damaged due to their exposure to DBCP. a. Michael DiBartolomeis’s expert report and testimony Plaintiffs’ toxicologist, DiBartolomeis, prepared an expert report expressing his opinion that Arias’s health problems were 8 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** likely caused by his exposure to DBCP while working on Bandeco’s banana farms. Despite not knowing the precise levels of DBCP present in the farms, DiBartolomeis noted that “even short-term exposures to relatively low[] concentrations of DBCP in the air could be toxic to the male reproductive system.” DiBartolomeis opined that Arias’s exposure to DBCP most likely occurred via inhalation and potential dermal contact while working inside the packing facilities, walking in the open fields beneath the canopies of banana plants, and sleeping in the warehouse where chemicals were stored. DiBartolomeis also observed that Arias’s infertility and his wife’s miscarriages were “consistent with the known toxic effects of DBCP exposure in humans.” DiBartolomeis relied on several human studies that focused on occupational exposure to DBCP in agricultural settings, including one by Martin Kharrazi, Gad Potashnik, and John R. Goldsmith that evaluated the pregnancy outcomes of married women whose husbands were employed as banana workers in Israel. Martin Kharrazi, Gad Potashnik, and John R. Goldsmith, Reproductive Effects of Dibromochloropropane, 16 Israel J. Med. Sci. 403, at 404 (1980) (“Kharrazi Study”). The authors interviewed 62 men, 56 of whom worked in direct contact with DBCP, and found that, [o]f 197 pregnancies reported for the total study group, 76 occurred before any contact with DBCP and 121, after the initial exposure. Of the 76 pregnancies before DBCP contact, 71 resulted in livebirths and 5 (6.6% of 9 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** pregnancies), in spontaneous abortion; of the 121 pregnancies after initial DBCP exposure, 97 resulted in livebirths and 24 (19.8% of pregnancies), in spontaneous abortion. Reproductive Effects of Dibromochloropropane, 16 Israel J. Med. Sci., at 404. The authors cautioned that “[a]lthough the design of this type of epidemiologic study can only point to associations and cannot prove a causal relationship, it is plausible that DBCP is causing an increased rate of spontaneous abortion in the exposed population through its effect on spermatogenesis.” Reproductive Effects of Dibromochloropropane, 16 Israel J. Med. Sci., at 405. Based on the Kharrazi Study and others, DiBartolomeis “conclude[d] within a reasonable degree of scientific probability that [Arias’s] exposure to DBCP . . . is the most plausible explanation for [his] testicular injury, oligospermia, and poor pregnancy outcomes.” b. Dow’s motion for summary judgment Dow moved for summary judgment on the operative complaint, but only as to Arias. Del Monte filed a joinder. Dow disputed the causation element of the negligence claim, contending Plaintiffs offered no evidence that Arias had any contact with DBCP. Dow relied on Arias’s admissions that he did not apply DBCP, did not work in the areas where DBCP was applied, could not identify a container of DBCP, and never witnessed its application to argue that no genuine dispute of material fact 10 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** existed as to whether he was exposed to DBCP and whether DBCP caused his alleged infertility and his wife’s miscarriages. Dow further asserted that DiBartolomeis’s expert report and testimony failed to create a genuine dispute that DBCP caused Arias’s alleged injuries. Dow opposed DiBartolomeis’s reliance on the Kharrazi Study, noting that, unlike the fifty-six married banana workers, Arias admitted he had no direct contact with DBCP. Dow argued that DiBartolomeis’s opinion rested on a study involving a population whose work history bore no resemblance to Arias’s. c. Dow’s motion in limine Dow concurrently filed a motion in limine to preclude DiBartolomeis’s expert report and testimony. Del Monte filed a joinder. Dow argued that DiBartolomeis’s opinions were speculative, unreliable, and unsupported by the facts because he improperly assumed that Arias spent four hours in the fields each afternoon, despite Arias’s testimony that he visited only “once in a while,” and that Arias was exposed to DBCP via inhalation on and immediately after application days, even though Arias admitted he never observed any applications. Dow also disputed DiBartolomeis’s opinion that DBCP was a “substantial factor” in causing Mastiel’s alleged miscarriages, arguing that the opinion was based solely on the Kharrazi Study, whose authors expressly stated could not prove causation. 11 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** d. Circuit court orders granting Dow’s motions Following a hearing, the circuit court granted Dow’s motions for summary judgment and in limine and Del Monte’s joinders. The circuit court concluded that Arias failed to establish a prima facie case of legal causation because the record contained no evidence of his exposure to DBCP, and that DiBartolomeis’s opinions thus lacked an evidentiary basis for causation in fact. 3. ICA proceedings The ICA vacated the circuit court’s orders granting Dow’s motions for summary judgment and in limine. Patrickson v. Dole Food Co., Inc., No. CAAP-XX-XXXXXXX, 2025 WL 2693624, at *6 (Haw. App. Sept. 22, 2025) (mem. op.). The ICA concluded that Arias’s deposition testimony raises genuine issues of material fact regarding his alleged exposure to DBCP and the adverse effects such exposure had on his and his wife’s health. Id. 4. Certiorari proceedings On certiorari, Defendants raise the following questions: 1. Toxic Tort Causation Standard. When the only evidence is that Plaintiff, a fruit inspector, worked away from the fields where the subject chemical (DBCP) was applied, never saw DBCP being applied, and never worked with it himself, is it sufficient for the plaintiff to proceed to trial when he merely “must have [had] some exposure because he was on the farm” where it was applied? 2. Appellate Standard of Review of the Trial Court’s Gatekeeper Review of Expert Testimony. Did the ICA gravely err when it used a summary judgment standard in evaluating an expert’s causation testimony instead of evaluating the testimony for reliability and relevancy, and when it 12 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** effectively applied a de novo review, rather than an abuse of discretion standard? Defendants essentially urge this court to adopt the frequency, regularity, and proximity test applied in asbestos cases like Fowler v. Akzo Nobel Chemicals, Inc., 251 N.J. 300, 334 (N.J. 2022), as the standard governing causation in toxic tort cases and to require plaintiffs to prove dosage as part of that showing. They also ask this court to decide whether the ICA erred in applying the summary judgment standard to DiBartolomeis’s causation testimony rather than evaluating the testimony for reliability and relevancy under an abuse of discretion standard. II. Standard of Review A. Motion for summary judgment An appellate court reviews an award of summary judgment de novo under the same standard applied by the circuit court. Fujimoto v. Au, 95 Hawaiʻi 116, 136, 19 P.3d 699, 719 (2001) (citation omitted). This court articulated the standard as follows: Summary judgment is appropriate if 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. Id. (citations omitted). We must review the evidence in the light most favorable to the party opposing the motion for 13 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** summary judgment. 95 Hawaiʻi at 137, 19 P.3d at 720 (citations omitted). We have further explained the burdens of the moving and non-moving parties on summary judgment as follows: The burden is on the party moving for summary judgment (moving party) to show the absence of any genuine issue as to all material facts, which, under applicable principles of substantive law, entitles the moving party to judgment as a matter of law. This burden has two components. First, the moving party has the burden of producing support for its claim that: (1) no genuine issue of material fact exists with respect to the essential elements of the claim or defense which the motion seeks to establish or which the motion questions; and (2) based on the undisputed facts, it is entitled to summary judgment as a matter of law. Only when the moving party satisfies its initial burden of production does the burden shift to the non-moving party to respond to the motion for summary judgment and demonstrate specific facts, as opposed to general allegations, that present a genuine issue worthy of trial. Second, the moving party bears the ultimate burden of persuasion. This burden always remains with the moving party and requires the moving party to convince the court that no genuine issue of material fact exists and that the moving part[y] is entitled to summary judgment as a matter of law. French v. Hawaii Pizza Hut, Inc., 105 Hawaiʻi 462, 470, 99 P.3d 1046, 1054 (2004) (citation and emphasis omitted). This court has prescribed detailed guidance regarding how a moving party may satisfy its initial burden on a motion for summary judgment, providing that: a summary judgment movant may satisfy [their] initial burden of production by either (1) producing admissible evidence to show there was no genuine issue of material fact, or (2) showing that the non-moving party cannot carry [their] burden of proof at trial.... [T]he movant generally cannot support its initial burden of production by pointing solely to the non-moving party’s lack of evidence if discovery has not concluded. 14 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** Ralston v. Yim, 129 Hawaiʻi 46, 48, 292 P.3d 1276, 1278 (2013) (citation omitted). III. Discussion A. Causation standard in toxic tort cases This court first addressed the causation element in toxic tort cases in Smith, 72 Haw. 416, 823 P.2d 717. There, the appellant was a hemophiliac who tested HIV-positive with the AIDS virus and claimed that his exposure to the virus occurred through injections of the Antihemophilic Factor Concentrate (AHF). Smith, 72 Haw. at 421-22, 823 P.2d at 721. Appellant sued the four AHF manufacturers for negligence and strict liability, and the manufacturers moved for summary judgment. Smith, 72 Haw. at 422, 823 P.2d at 722. The United States District Court for the District of Hawaiʻi (“USDC-HI”) granted summary judgment in favor of the manufacturers, “holding that appellant failed to prove specifically which manufacturer’s product caused his infection.” Smith, 72 Haw. at 422-23, 823 P.2d at 722. The case came before this court through certified questions from the United States Court of Appeals for the Ninth Circuit, one of which concerned the causation factor in negligence cases: 3. Would Hawaii allow recovery in this case when the identity of the actual tortfeasor cannot be proven? If Hawaii would allow recovery, what theory (i.e. burden-shifting, enterprise liability, market share or other) would the Hawaiʻi Supreme Court adopt? 15 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** . . . . In considering our response to the questions, we note that the issue as to question[] . . . three concerns the causation factor in negligence. The instant problem is that the plaintiff cannot identify which particular defendant caused his injury. Smith, 72 Haw. at 419-20, 823 P.2d at 720. We responded “yes” to question three and adopted “the alternative market share theory of recovery.”5 Smith, 72 Haw. at 421, 823 P.2d at 721. In considering the third question, we explained that we would need to “deviat[e] from the traditional proof in a negligence case, which . . . includes the factor of causation” because in mass tort cases, plaintiffs might not be able to identify the actual entity responsible for their injuries: As discussed in the American Law Institute Enterprise Responsibility for Personal Injuries—Reporter’s Study (1991) (ALI Study), the field of torts has now expanded to include personal injury actions described in three tiers of actions. . . . [T]he third tier includes “mass” torts where toxic exposure to many plaintiffs may, many years later, cause cancer or other illness. . . . It is this final tier with which this case deals. It necessitates considering how to fairly deal with the plight of plaintiffs unable to identify, for no fault of their own, the person or entity who should bear the liability for their injury. Smith, 72 Haw. at 426, 428, 823 P.2d at 723, 724 (emphasis added). We then more generally recognized that new rules of causation would need to be adopted for mass tort cases: 5 The alternative market share theory of recovery is defined as follows: Where the conduct of two or more actors is tortious, and it is proved that harm has been caused to the plaintiff by only one of them, but there is uncertainty as to which one has caused it, the burden is upon each such actor to prove that he has not caused the harm. Restatement (Second) of Torts § 433B(3) (1965) (“Second Restatement”). 16 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** No longer can we apply traditional rules of negligence, such as those used in individual and low level negligence to mass tort cases, especially here, where we are dealing with a pharmaceutical industry that dispenses drugs on a wide scale that could cause massive injuries to the public, and where fungibility makes the strict requirements difficult to meet. The problem calls for adopting new rules of causation, for otherwise innocent plaintiffs would be left without a remedy. Smith, 72 Haw. at 428, 823 P.2d at 724 (emphasis added). Ultimately, this court adopted the alternative market share theory of recovery but did not set forth a new rule of causation. But this court explicitly recognized the need for new approaches to causation in toxic tort cases. More recently, in Feindt v. United States, CIV NO. 22-00397 LEK-KJM, 2025 WL 1348465, at *2 (D. Haw. May 7, 2025), the USDC- HI addressed a negligence action brought by seventeen plaintiffs who sustained personal injuries “from ingesting and being exposed to drinking water that was contaminated by jet fuel.” Recognizing that we have not developed a test for causation in toxic tort cases, the Feindt court predicted how we would resolve the issue. First, it anticipated that we would require expert testimony on the causation factor: There is no controlling Hawaiʻi law specifically addressing the test for legal causation in toxic tort cases. The Court must therefore predict how the Hawaiʻi Supreme Court will decide the issue. See Judd v. Weinstein, 967 F.3d 952, 955– 56 (9th Cir. 2020). The Court predicts that the Hawaiʻi Supreme Court would hold that the same test applied in medical negligence cases would extend to toxic tort actions. Namely, that expert testimony is required to determine causation. 17 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** Feindt, 2025 WL 1348465, at *4 (emphasis added).6 Second, the Feindt court applied the causation test in Hanford, 292 F.3d at 1133, a toxic tort case involving thousands of plaintiffs who were allegedly exposed to radioactive emissions from a federal nuclear facility. In Hanford, the Ninth Circuit analyzed causation in terms of general and specific causation: General, or “generic” causation has been defined by courts to mean whether the substance at issue had the capacity to cause the harm alleged, while [specific causation or] “individual causation” refers to whether a particular individual suffers from a particular ailment as a result of exposure to a substance. Feindt, 2025 WL 1348465, at *4. Applying this bifurcated test, the Feindt court determined there was sufficient expert testimony evidence to support a finding “that the chemicals contained in the [jet fuel] had the capacity to cause the harm alleged by [p]laintiffs” (general causation) and that certain 6 The requirement of expert testimony is one component of the causation test in medical negligence cases, see Est. of Frey v. Mastroianni, 146 Hawaiʻi 540, 550–51, 463 P.3d 1197, 1207–08 (2020), and toxic tort cases, see In re Hanford Nuclear Rsrv. Litig., 292 F.3d 1124, 1133 (9th Cir. 2002). In Exotics Hawaii-Kona, Inc. v. E.I. Du Pont De Nemours & Co., this court stated the rationale for requiring expert testimony to prove causation in medical negligence cases, reasoning that “‘lay jurors are ill prepared to evaluate complicated technical data for the purpose of determining whether professional conduct conformed to a reasonable standard of care and whether there is a causal relationship between the violation of a duty and an injury to the patient.’” Exotics, 116 Hawaiʻi 277, 299-300, 172 P.3d 1021, 1043-44 (2007) (citation omitted); see Craft v. Peebles, 78 Hawaiʻi 287, 298, 893 P.2d 138, 149 (1995) (finding it well-settled in medical malpractice cases that “the question of negligence must be decided by reference to relevant medical standards of care for which the plaintiff carries the burden of proving through expert medical testimony,” since “a jury generally lacks the requisite special knowledge, technical training, and background to be able to determine the applicable standard without the assistance of an expert”). 18 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** plaintiffs sustained injuries from their “exposure to the chemicals contained in the [jet fuel]” (specific causation). Feindt, 2025 WL 1348465, at *5. Moreover, upon finding “that the actual and specific amount of jet fuel chemicals . . . released into the water supply . . . [wa]s not capable of being reliably calculated,” it concluded that plaintiffs were not required to specify “the actual dose to which each individual . . . was exposed” to prove causation. Feindt, 2025 WL 1348465, at *6. Finally, in addition to applying general and specific causation, the Feindt court also applied the substantial factor test that this court adopted in Mitchell v. Branch, 45 Haw. 128, 132, 363 P.2d 969, 973 (1961) to ascertain “whether [the] defendant’s conduct was ‘a substantial factor in bringing about the [plaintiffs’] harm[s].’” Feindt, 2025 WL 1348465, at *8 (citing O’Grady v. State, 140 Hawaiʻi 36, 44, 398 P.3d 625, 633 (2017)), *7-30. In Mitchell, 45 Haw. at 132, 363 P.2d at 973, we adopted the Restatement (First) of Torts’ (“First Restatement”) test for legal cause, which reads: The actor’s negligent conduct is a legal cause of harm to another if (a) his conduct is a substantial factor in bringing about the harm, and (b) there is no rule of law relieving the actor from liability because of the manner in which his negligence has resulted in the harm. 19 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** Restatement (First) of Torts § 431 (1934) (emphasis added) (“Mitchell test”). However, in Smith, this court recognized that toxic tort cases require new rules of causation and thus rejected the substantial factor test in favor of the alternative market share theory of recovery. Smith, 72 Haw. at 421, 428, 823 P.2d at 721, 724. But although Smith did not cite Mitchell directly, it did reference Knodle v. Waikiki Gateway Hotel, Inc., which reaffirmed the Mitchell test as “‘[t]he best definition and the most workable test of proximate or legal cause.’” Knodle, 69 Haw. 376, 390, 742 P.2d 377, 386 (1987) (citing Mitchell, 45 Haw. at 132, 363 P.2d at 973); see Smith, 72 Haw. at 426, 823 P.2d at 723. Therefore, it is understandable why the Feindt court predicted that this court would continue to rely on the substantial factor test. Smith established that the substantial factor test was unworkable in mass toxic tort cases because it could leave innocent plaintiffs without a remedy. Smith, 72 Haw. at 428, 823 P.2d at 724. In fact, the Feindt court determined that plaintiffs failed to meet this causation standard with respect to at least some of the injuries alleged. Feindt, 2025 WL 1348465, at *8. 20 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** And recognizing this court’s statement in Smith that mass toxic tort cases require new rules of causation, Defendants urge this court to adopt the frequency, regularity, and proximity test used in asbestos litigation, citing Fowler, 251 N.J. 300, as an example. But as the New Jersey Supreme Court clarified in Fowler, 251 N.J. at 336, “[t]he frequency, regularity, and proximity test is merely an articulation of what constitutes a substantial factor for purposes of determining proximate cause in an occupational exposure setting.” In other words, the two tests are functionally equivalent. Federal caselaw cited by Defendants supports this conclusion. See Menne v. Celotex Corp., 861 F.2d 1453, 1464 (10th Cir. 1988); Lohrmann v. Pittsburgh Corning Corp., 782 F.2d 1156, 1162 (4th Cir. 1986). It is therefore time for this court to determine how causation should be addressed in mass toxic tort cases. In this regard, this court has turned to the Restatement of Torts on various occasions to determine how we should address developing areas of tort law. See Bynum v. Mango, 106 Hawaiʻi 81, 86 n.12, 101 P.3d 1149, 1154 n.12 (2004) (noting this court has relied on the American Law Institute’s restatements of torts as persuasive authority); Guieb v. Guieb, 156 Hawaiʻi 162, 170- 71, 571 P.3d 382, 390-91 (2025) (adopting new punitive damages standard from Third Restatement of Torts: Phys. & Emot. Harm § 21 *** FOR PUBLICATION IN WEST’S HAWAI‘I REPORTS AND PACIFIC REPORTER *** 39) Indeed, the Mitchell test was based on the First Restatement of Torts. We now adopt the causation test for toxic tort cases set out in comment g to section 26 of the Third Restatement. See Restatement (Third) of Torts: Phys. & Emot. Harm § 26, cmt. g. In these types of cases, the Third Restatement defines causation in terms of (1) general causation, (2) specific causation, and (3) exposure to the agent: In toxic-substances cases, the causal inquiry is modified by the limits of and available forms of scientific evidence. That inquiry often must address whether the agent for which the actor is responsible is capable of causing the disease from which another suffers (known as general causation). In addition, the question whether the agent caused the specific plaintiff’s disease (known as specific causation) is confronted. See [Restatement (Third) of Torts] § 28, [cmt.] c(3) and c(4). In addition, a person’s exposure to the actor’s agent is another necessary aspect for factual cause to exist. See [Restatement (Third) of Torts] § 28, [cmt.] c(2). Each of these distinct inquiries is a component of the factual-cause inquiry. Restatement (Third)