In Ontario, the threshold question in determining if an employee can maintain an action for negligence against their employer is whether the injury suffered falls within the ambit of the insurance plan established by the Workplace Safety and Insurance Act, 1997 (“WSIA”). The entitlement to worker’s compensation benefits extinguishes all rights of action that an employee may have against their employer for negligence outside of the WSIA.
In order for the WSIA to oust a worker's right of action, the contraction of a disease in the midst of an outbreak must be an “accident” or “disease” that gives rise to an entitlement to benefits under the WSIA. In determining whether a worker has entitlement for a disease, the Workplace Safety and Insurance Tribunal generally considers whether workplace exposures made a significant contribution to the development of the claimed condition. A significant contributing factor is one of considerable effect or importance. It need not be the sole contributing factor. In Ontario, whether the risk contribution is more than “beyond that faced in the community at large” is not part of the legal test used to determine the work‑relatedness of a disease. (Decision No. 2970/16)
If an illness is found not to be an occupational disease (or an accident), it will not give rise to an entitlement to worker’s compensation benefits, and therefore will not displace the worker’s common law right of action in negligence (Workplace Safety and Insurance Act, 1997). Further, if the employer is not included in Schedule 1 or 2 of the WSIA, the employer and its employees’ rights are governed by Part X of the WSIA, which preserves a worker’s right of action in negligence. (Fleming v. Massey)
If an employee may bring an action in negligence against its employer, they must prove all of the elements of negligence on a balance of probabilities in order to be successful: duty of care, breach, causation, and damages (Clements v. Clements).
The duty of care to prevent the spread of an infectious disease during an outbreak has been discussed (Williams v. Ontario; Abarquez v. Ontario), but never in the context of an employment relationship. However, it has long been recognized that employers have a common law duty of care to take reasonable care for the safety of their workers (Spicer v. Dresler). Employers also have a statutory duty of care to take every precaution reasonable in the circumstances for the protection of a worker under s. 25(2)(h) of the Occupational Health and Safety Act.
An employer’s duty of care to employees can arise in a number of ways. In Spicer v. Dresler, the Ontario Superior Court of Justice stated in obiter that the employer of a person employed to care for children with disabilities would have a duty to advise and warn its employees if one of the children had a major health problem or a serious infectious disease which posed a danger to the employee because of its potential to transmit to others. No further case law speaking to an employer’s duty of care to an employee with regard to infectious diseases could be identified. However, one could argue that what is reasonable in the circumstances of a pandemic is to follow official guidance from the government and health organizations.
Causation may be a bigger hurdle for an employee seeking to sue their employer in negligence for failing to prevent the spread of a disease because, in the case of an outbreak in the community at large, it will be difficult to pinpoint where or how they were exposed to the disease. The basic rule of recovery for negligence is that the plaintiff must establish on a balance of probabilities that the defendant caused the plaintiff's injury on the "but for" test. This is a factual determination. Exceptionally, however, courts have accepted that a plaintiff may be able to recover on the basis of "material contribution to risk of injury", without showing factual "but for" causation. This can occur in cases where it is impossible to determine which of a number of negligent acts by multiple actors in fact caused the injury, but it is established that one or more of them did in fact cause it. (Clements v. Clements)
Even if the "material contribution" test is not applicable, the "but for" causation test must be applied in a robust, common sense fashion. There is no need for scientific evidence of the precise contribution the defendant's negligence made to the injury. Evidence connecting the breach of duty to the injury suffered may permit the judge, depending on the circumstances, to infer that the defendant's negligence probably caused the loss. (Clements v. Clements; Walker Estate v. York Finch General Hospital)
The initial question in determining if an employee can maintain an action for negligence against their employer is whether the injury suffered falls within the insurance plan established by the Workplace Safety and Insurance Act, 1997, SO 1997, c 16, Sch A (“WSIA”). Section 26(2) of the WSIA provides that the entitlement to worker’s compensation benefits extinguishes all rights of action outside of the WSIA:
Benefits in lieu of rights of action
26 (2) Entitlement to benefits under the insurance plan is in lieu of all rights of action (statutory or otherwise) that a worker, a worker’s survivor or a worker’s spouse, child or dependant has or may have against the worker’s employer or an executive officer of the employer for or by reason of an accident happening to the worker or an occupational disease contracted by the worker while in the employment of the employer. 1997, c. 16, Sched. A, s. 26 (2); 1999, c. 6, s. 67 (6); 2005, c. 5, s. 73 (6).
For employees working in industries listed in Schedules 1 and 2 of the WSIA (which covers most workers), the no-fault loss of earnings benefits provided by the WSIA completely displaces all common law rights of action that workers may otherwise have against their employer (Fleming v. Massey, 2016 ONCA 70 (CanLII), leave to appeal refused, Andrew Massey, et al. v. Derek Fleming, 2016 CanLII 33997 (SCC) (“Fleming”), para. 24). The industries falling under Schedule 1 and 2 are listed in General, O Reg 175/98. Employers in Schedule 1 industries are required to contribute to the insurance fund, while employers in Schedule 2 are individually liable to pay benefits under the WSIA’s general provisions (Fleming, para. 22).
Section 29 provides that a Schedule 1 or 2 employer who is found to be negligent in respect of an accident or disease that gives rise to an entitlement to WSIA benefits is not liable to pay any damages to a worker or to contribute to or indemnify another person who may be liable to pay such damages (Fleming, para. 23):
Liability where negligence, fault
29 (1) This section applies in the following circumstances:
1. In an action by or on behalf of a worker employed by a Schedule 1 employer or a survivor of such a worker, any Schedule 1 employer or a director, executive officer or another worker employed by a Schedule 1 employer is determined to be at fault or negligent in respect of the accident or the disease that gives rise to the worker’s entitlement to benefits under the insurance plan.
2. In an action by or on behalf of a worker employed by a Schedule 2 employer or a survivor of such a worker, the worker’s Schedule 2 employer or a director, executive officer or another worker employed by the employer is determined to be at fault or negligent in respect of the accident or the disease that gives rise to the worker’s entitlement to benefits under the insurance plan.
Same
(2) The employer, director, executive officer or other worker is not liable to pay damages to the worker or his or her survivors or to contribute to or indemnify another person who is liable to pay such damages.
Determination of fault
(3) The court shall determine what portion of the loss or damage was caused by the fault or negligence of the employer, director, executive officer or other worker and shall do so whether or not he, she or it is a party to the action.
Same
(4) No damages, contribution or indemnity for the amount determined under subsection (3) to be caused by a person described in that subsection is recoverable in an action. 1997, c. 16, Sched. A, s. 29.
The issue then becomes whether the contraction of a disease in the midst of an outbreak is an “accident” or “disease” that gives rise to an entitlement to benefits under the WSIA. Section 2(1) of the WSIA defines “accident” as:
(a) a wilful and intentional act, not being the act of the worker,
(b) a chance event occasioned by a physical or natural cause, or
(c) disablement arising out of and in the course of employment.
With respect to diseases, the WSIA uses the term “occupational disease”, which is defined as:
(a) a disease resulting from exposure to a substance relating to a particular process, trade or occupation in an industry,
(b) a disease peculiar to or characteristic of a particular industrial process, trade or occupation,
(c) a medical condition that in the opinion of the Workplace Safety and Insurance Board requires a worker to be removed either temporarily or permanently from exposure to a substance because the condition may be a precursor to an occupational disease,
(d) a disease mentioned in Schedule 3 or 4 of O. Reg. 175/98, which can generally be categorized into: poisoning from workplace exposures, diseases caused by biological agents (such as anthrax and tuberculosis), diseases caused by physical agents such as repetitive motion or friction/pressure, and respiratory diseases, skin and eye diseases and cancer caused by workplace exposures; or
(e) a disease otherwise prescribed under the regulations.
In Decision No. 2970/16, 2017 ONWSIAT 592 (CanLII), the Ontario Workplace Safety and Insurance Appeals Tribunal (‘the Tribunal”) dealt with an employee’s claim for benefits when she developed a respiratory illness after an outbreak was declared at her workplace, a long-term care facility. The Workplace Safety and Insurance Board (“the Board”) denied her claim for benefits and she appealed to the Tribunal. The Tribunal accepted that the employee’s symptoms were consistent with the condition which resulted in the outbreak declaration and found that she was entitled to benefits, explaining its reasoning as follows:
[6] The Tribunal will usually determine entitlement in accordance with whether there was an “accident” in the nature of a “disablement arising out of and in the course of employment”, based on the evidence in the case. See Decisions No. 1480/98 and 1294/05.
[7] In its letter dated July 5, 2012, the Board noted that in order “for a communicable disease to be compensable, it must be established that employment made a significant contribution to the risk of contracting illness, beyond that faced in the community at large”. The employer argued that this test implicitly must satisfy whether there was an increased risk at the workplace of developing respiratory symptoms.
[8] In determining whether a worker has entitlement for an occupational disease, however, the Tribunal generally considers whether the workplace exposures made a significant contribution to the development of the claimed condition. A significant contributing factor is one of considerable effect or importance. It need not be the sole contributing factor. See, for example, Decision No. 280. Whether the risk contribution is more than “beyond that faced in the community at large” is not part of the legal test used by the Tribunal to determine work‑relatedness of a disease.
In WCAT-2016-00994 (Re), 2016 CanLII 152400 (BC WCAT), the British Columbia Workers’ Compensation Appeal Tribunal found that a registered nurse’s influenza was an occupational disease arising due to the nature of her employment because she was at an increased risk compared to the general population:
[25] In terms of the fact that the worker suffered from influenza A, I accept that influenza A is a common illness in the general community, particularly during the time of year that the worker developed her condition. Nevertheless, while influenza undoubtedly existed in the worker’s general community, in her case there was a known influenza outbreak on the wards where she worked. That fact reasonably establishes that there would have been an increased risk involved compared to the population at large.
It therefore appears that the test used in BC and Ontario to determine whether an illness is an “occupational disease” is different. In BC, if the nature of a worker’s employment is such that it puts them at an increased risk of an infectious disease compared to the general population, that worker’s claim will likely be entitled to provincial worker’s compensation. In Ontario the bar appears to be lower, in that being at an increased risk compared to the community at large is not necessary. Instead, the workplace exposures need only make a “significant contribution”.
If an illness is found not to be an occupational disease (or an accident), it will not give rise to an entitlement to worker’s compensation benefits, and therefore will not displace the worker’s common law right of action in negligence (WSIA s. 26(2)).
Further, if the employer is not included in Schedule 1 or 2 of the WSIA, the employer and its employees’ rights are governed by Part X of the WSIA, which preserves a worker’s right of action in negligence. In Fleming, the Court explained:
[25] Part X of the WSIA is a small exception to this general scheme. Part X applies to the small number of workers not employed in either Schedule 1 or Schedule 2 industries. Employers under Part X neither contribute to the insurance fund nor are liable to pay benefits. Rather, Part X provides workers with certain statutory rights of action for damages that abrogate some of the common law doctrines that restricted a worker’s right to recover.
Under subsections 114(1)(2) and (3) of Part X of the WSIA, an employee may bring an action in negligence against their employer:
Employer’s liability
114 (1) A worker may bring an action for damages against his or her employer for an injury that occurs in any of the following circumstances:
1. The worker is injured by reason of a defect in the condition or arrangement of the ways, works, machinery, plant, buildings or premises used in the employer’s business or connected with or intended for that business.
2. The worker is injured by reason of the employer’s negligence.
3. The worker is injured by reason of the negligence of a person in the employer’s service who is acting within the scope of his or her employment.
If an employee may bring an action in negligence against its employer, they must prove all of the elements of negligence on a balance of probabilities in order to be successful: duty of care, breach, causation, and damages (Clements v. Clements, [2012] 2 SCR 181, 2012 SCC 32 (CanLII), paras. 6-7).
The duty of care to prevent the spread of an infectious disease during an outbreak has been discussed, but never in the context of an employment relationship. In Williams v. Ontario, 2009 ONCA 378 (CanLII), leave to appeal refused, [2009] S.C.C.A. No. 298 (“Williams”), the plaintiff brought a class action against Ontario on behalf of individuals who contracted SARS. The claim alleged that the province was negligent in its response to the disease. The province brought a motion to strike the Statement of Claim on the basis that the province did not owe the plaintiff a private law duty of care. The motions judge and Ontario Court of Appeal agreed.
In Abarquez v. Ontario, 2009 ONCA 374 (CanLII), the plaintiffs were nurses who worked in Toronto during the SARS outbreak. With respect to their negligence claim, the nurses alleged that the emergency measures taken by the provincial government were insufficient to ensure their safety. Like in Williams, the provincial government moved to strike the statement of claim on the ground that it did not owe the nurses a private law duty of care. The nurses argued that their case was distinguishable from Williams because the province had issued directives regarding the care of SARS patients, placing it into a relationship of proximity sufficient to ground a duty of care. Specifically, the nurses argued that Ontario’s conduct put it in the position of their employer or supervisor. However, the Court of Appeal disagreed:
[33] The hospitals that employed the nurses, supervised their day-to-day working conditions and bore immediate responsibility for the safety of their workplace are autonomous entities under the Public Hospitals Act, R.S.O. 1990, c. P.40. I agree with Ontario's submission that it is plain and obvious that the Directives issued during the SARS crisis could not alter the legal autonomy of the hospitals or amount to an assumption of control by Ontario over their day-to-day operation. The general power to mandate standards for the control of infectious diseases simply cannot be equated with the kind of direct involvement in the day-to-day management of employees that being an employer or supervisor entails. The Directives to the hospitals may well have had an impact upon workplace safety but that is far removed from taking "charge" over a workplace or assuming employer-like "authority" over a worker. Ontario is simply is too far removed from the day-to-day operation of the hospitals and the day-to-day working conditions of nurses to be a supervisor under the OHSA.
However, it has long been recognized that employers have a common law duty of care to take reasonable care for the safety of their workers (Spicer v. Dresler, 2018 ONSC 5770 (CanLII) (“Spicer”), para. 18). Employers also have a statutory duty of care to take every precaution reasonable in the circumstances for the protection of a worker under s. 25(2)(h) of the Occupational Health and Safety Act, RSO 1990, c O.1.
An employer’s duty of care to employees can arise in a number of ways. In Spicer, the Ontario Superior Court of Justice stated in obiter that the employer of a person employed to care for children with disabilities would have a duty to advise and warn its employees if one of the children had a major health problem or a serious infectious disease which posed a danger to the employee because of its potential to transmit to others (para. 19). No further case law speaking to an employer’s duty of care to an employee with regard to infectious diseases could be identified. However, one could argue that what is reasonable in the circumstances of a pandemic is to follow official guidance from the government and health organizations.
Causation may be a bigger hurdle for an employee seeking to sue their employer in negligence for failing to prevent the spread of a disease because, in the case of an outbreak in the community at large, it will be difficult to pinpoint where or how they were exposed to the disease. The employer may argue that the employee cannot prove that they contracted the disease at work. However, the employee can argue in response that they do not need to prove where they contracted the disease with scientific precision in order to prove legal causation. The Supreme Court set out the principles of causation in Clements v. Clements, [2012] 2 SCR 181, 2012 SCC 32 (CanLII) (“Clements”):
[8] The test for showing causation is the "but for" test. The plaintiff must show on a balance of probabilities that "but for" the defendant's negligent act, the injury would not have occurred. Inherent in the phrase "but for" is the requirement that the defendant's negligence was necessary to bring about the injury — in other words that the injury would not have occurred without the defendant's negligence. This is a factual inquiry. If the plaintiff does not establish this on a balance of probabilities, having regard to all the evidence, her action against the defendant fails.
[9] The "but for" causation test must be applied in a robust common sense fashion. There is no need for scientific evidence of the precise contribution the defendant's negligence made to the injury. See Wilsher v. Essex Area Health Authority, [1988] A.C. 1074 (U.K. H.L.), at p. 1090, per Lord Bridge; Snell v. Farrell, [1990] 2 S.C.R. 311 (S.C.C.).
[10] A common sense inference of "but for" causation from proof of negligence usually flows without difficulty. Evidence connecting the breach of duty to the injury suffered may permit the judge, depending on the circumstances, to infer that the defendant's negligence probably caused the loss. See Snell and Athey v. Leonati, [1996] 3 S.C.R. 458 (S.C.C.). See also the discussion on this issue by the Australian courts: Betts v. Whittingslowe, [1945] H.C.A. 31, 71 C.L.R. 637, at p. 649; Bennett v. Minister of Community Welfare, [1992] H.C.A. 27, 176 C.L.R. 408 (Australia H.C.), at pp. 415-16; Flounders v. Millar, [2007] NSWCA 238, 49 M.V.R. 53; Roads and Traffic Authority v. Royal, [2008] H.C.A. 19, 245 A.L.R. 653, at paras. 137-44.
[11] Where "but for" causation is established by inference only, it is open to the defendant to argue or call evidence that the accident would have happened without the defendant's negligence, i.e. that the negligence was not a necessary cause of the injury, which was, in any event, inevitable. As Sopinka J. put it in Snell, at p. 330:
The legal or ultimate burden remains with the plaintiff, but in the absence of evidence to the contrary adduced by the defendant, an inference of causation may be drawn although positive or scientific proof of causation has not been adduced. If some evidence to the contrary is adduced by the defendant, the trial judge is entitled to take account of Lord Mansfield's famous precept [that "all evidence is to be weighed according to the proof which it was in the power of one side to have produced, and in the power of the other to have contradicted" (Blatch v. Archer (1774), 1 Cowp. 63, 98 E.R. 969, at p. 970)]. This is, I believe, what Lord Bridge had in mind in Wilsher when he referred to a "robust and pragmatic approach to the ... facts" (p. 569).
[12] In some cases, an injury — the loss for which the plaintiff claims compensation — may flow from a number of different negligent acts committed by different actors, each of which is a necessary or "but for" cause of the injury. In such cases, the defendants are said to be jointly and severally liable. The judge or jury then apportions liability according to the degree of fault of each defendant pursuant to contributory negligence legislation.
[13] To recap, the basic rule of recovery for negligence is that the plaintiff must establish on a balance of probabilities that the defendant caused the plaintiff's injury on the "but for" test. This is a factual determination. Exceptionally, however, courts have accepted that a plaintiff may be able to recover on the basis of "material contribution to risk of injury", without showing factual "but for" causation. As will be discussed in more detail below, this can occur in cases where it is impossible to determine which of a number of negligent acts by multiple actors in fact caused the injury, but it is established that one or more of them did in fact cause it. In these cases, the goals of tort law and the underlying theory of corrective justice require that the defendant not be permitted to escape liability by pointing the finger at another wrongdoer. Courts have therefore held the defendant liable on the basis that he materially contributed to the risk of the injury.
[14] "But for" causation and liability on the basis of material contribution to risk are two different beasts. "But for" causation is a factual inquiry into what likely happened. The material contribution to risk test removes the requirement of "but for" causation and substitutes proof of material contribution to risk. As set out by Smith J.A. in MacDonald (Litigation Guardian of) v. Goertz, 2009 BCCA 358, 275 B.C.A.C. 68 (B.C. C.A.), at para. 17,
... "material contribution" does not signify a test of causation at all; rather it is a policy-driven rule of law designed to permit plaintiffs to recover in such cases despite their failure to prove causation. In such cases, plaintiffs are permitted to "jump the evidentiary gap": see "Lords a 'leaping evidentiary gaps", (2002) Torts Law Journal 276, and "Cause-in-Fact and the Scope of Liability for Consequences", (2003) 119 L.Q.R. 388, both by Professor Jane Stapleton. That is because to deny liability "would offend basic notions of fairness and justice": Hanke v. Resurfice Corp., para. 25.
[15] While the cases and scholars have sometimes spoken of "material contribution to the injury" instead of "material contribution to risk", the latter is the more accurate formulation. As will become clearer when we discuss the cases, "material contribution" as a substitute for the usual requirement of "but for" causation only applies where it is impossible to say that a particular defendant's negligent act in fact caused the injury. It imposes liability not because the evidence establishes that the defendant's act caused the injury, but because the act contributed to the risk that injury would occur. Thus this Court in Snell and Hanke v. Resurfice Corp., 2007 SCC 7, [2007] 1 S.C.R. 333 (S.C.C.), raised the possibility of a material contribution to risk approach. The English law takes the same approach, as discussed below.
[16] Elimination of proof of causation as an element of negligence is a "radical step that goes against the fundamental principle stated by Diplock L.J. in Browning v. War Office, [1962] 3 All E.R. 1089 (Eng. C.A.), at pp. 1094-95: '...[a] defendant in an action in negligence is not a wrongdoer at large; he is a wrongdoer only in respect of the damage which he actually causes to the plaintiff'": Mooney v. British Columbia (Attorney General), 2004 BCCA 402, 202 B.C.A.C. 74 (B.C. C.A.), at para. 157, per Smith J.A., concurring in the result. For that reason, recourse to a material contribution to risk approach is necessarily rare, and justified only where it is required by fairness and conforms to the principles that ground recovery in tort.
…
[39] What then are the cases referring to when they say that it must be "impossible" to prove "but for" causation as a precondition to a material contribution to risk approach? The answer emerges from the facts of the cases that have adopted such an approach. Typically, there are a number of tortfeasors. All are at fault, and one or more has in fact caused the plaintiff's injury. The plaintiff would not have been injured "but for" their negligence, viewed globally. However, because each can point the finger at the other, it is impossible for the plaintiff to show on a balance of probabilities that any one of them in fact caused her injury. This is the impossibility of which Cook and the multiple employer mesothelioma cases speak.
If an employee seeks to rely on the “material contribution” test but sues only their employer and there are no other probable sources of infection, the “material contribution” test may not be appropriate:
[42] The only case to apply a material contribution to risk approach to a single tortfeasor is Sienkiewicz. A plaintiff suffering from mesothelioma had only been exposed to asbestos from a single negligent source and on the trial judge's findings, "but for" causation could not be inferred. The United Kingdom Supreme Court took the view that it was bound by precedent to apply a material contribution to risk approach in all mesothelioma cases. Several members of the court in Sienkiewicz noted the difficulty with such a result. Lady Hale observed (at para. 167) that she found it hard to believe that a defendant "whose wrongful exposure might or might not have led to the disease would be liable in full for the consequences even if it was more likely than not that some other cause was to blame (let alone that it was not more likely than not that he was to blame)". In my view, nothing compels a similar result in Canada, and thus far, although Sopinka J.'s remarks in Snell (quoted above at para. 20) do not preclude it, courts in Canada have not applied a material contribution to risk test in a case with a single tortfeasor.
…
[44] This is not to say that new situations will not raise new considerations. I leave for another day, for example, the scenario that might arise in mass toxic tort litigation with multiple plaintiffs, where it is established statistically that the defendant's acts induced an injury on some members of the group, but it is impossible to know which ones.
In Walker Estate v. York Finch General Hospital, [2001] 1 SCR 647, 2001 SCC 23 (CanLII) (“Walker Estate”), the plaintiff had contracted HIV from tainted blood. Her estate sued the supplier of the blood for negligence in failing to screen out donors with a high risk of HIV by warning them not to give blood. The suppliers argued that “but for” causation was not established because persons with HIV who did not know of their condition or did not wish to disclose it might have donated blood irrespective of any screening measures employed by the suppliers. The Supreme Court rejected this argument and found the supplier liable, stating:
[88] In cases of negligent donor screening, it may be difficult or impossible to prove hypothetically what the donor would have done had he or she been properly screened by the C.R.C.S. The added element of donor conduct in these cases means that the but-for test could operate unfairly, highlighting the possibility of leaving legitimate plaintiffs uncompensated. Thus, the question in cases of negligent donor screening should not be whether the C.R.C.S.'s conduct was a necessary condition for the plaintiffs' injuries using the "but-for" test, but whether that conduct was a sufficient condition. The proper test for causation in cases of negligent donor screening is whether the defendant's negligence "materially contributed" to the occurrence of the injury. In the present case, it is clear that it did. "A contributing factor is material if it falls outside the de minimis range" (see Athey v. Leonati, [1996] 3 S.C.R. 458 (S.C.C.), at para. 15). As such, the plaintiff retains the burden of proving that the failure of the C.R.C.S. to screen donors with tainted blood materially contributed to Walker contracting HIV from the tainted blood.
Though this reads as an application of the “material contribution” test, the Supreme Court later in Clements described the Walker Estate decision as a “robust and common sense application of the ‘but for’ test of causation” (para. 28). Therefore, even if the “material contribution” test is not applicable, an employee may argue that causation could still be established under the robust application of the “but for” test called for by the Supreme Court in Clements.