There is no right of appeal from a decision of the Workplace Safety & Insurance Appeals Tribunal. Occasionally, a dissatisfied party will bring an application for a Judicial Review of a Tribunal decision.
A party who brings an application for judicial review may be liable to pay an award of court costs to the other parties, including the Tribunal, if the judicial review is dismissed by the Court. The amount of court costs assessed against the losing party on a judicial review is often several thousand dollars.
The courts have stated many times that on applications for judicial review they will treat decisions of the Tribunal with deference, so that a court will only interfere with a Tribunal decision if it is "irrational". For many years the courts held that there were three standards of review: correctness, reasonableness simpliciter, and patent unreasonableness. Numerous court decisions found that the standard of review for a Tribunal decision was whether it was "patently unreasonable", which was the most deferential standard possible.
The Supreme Court of Canada decision of Dunsmuir v New Brunswick  1 S.C.R. 190 ruled that the patent unreasonableness standard would no longer be recognized, so that the only standard of deference was reasonableness. However that has not affected how the courts assess Tribunal decisions. In Rodrigues v. Ontario (Workplace Safety & Insurance Appeals Tribunal) (2008) 92 O.R. (3d) 757 the Ontario Court of Appeal held that “reviewing courts can interfere only where the Tribunal's decision is clearly irrational”.
One reason the courts are reluctant to interfere with Tribunal decisions is Section 123 of the Workplace Safety & Insurance Act. Section 123 is a "privative" clause, which states that Tribunal decisions are not open to question or review in a court. The Court of Appeal has stated that even without a privative clause a decision of the Tribunal is still subject to deference. A very important reason the courts give great deference to Tribunal decisions is because the Tribunal is recognized as an expert body with special expertise in workplace safety and insurance matters.
On many occasions the courts have found that the Tribunal's decisions are not only not unreasonable, they are correct. (Rogers and Malfara v WCAT Dec. 7 1990, unreported, Divisional Court, Decision 258/90; Stelpipe v Franyo and WCAT Feb. 14 1991, unreported, Divisional Court, Decision 298/88; Canada Post v Johnson Nov. 28, 2003, Decisions 1480/98I and 1480/98, Canadian Pacific Railway v WCAT and Minshall (2000) O.J. No 500, Decision 647/95; Canada Post Corp. v. Smith, (1998), 40 O.R. (3d) 97(C.A.), Decision 716/91, leave to appeal to S.C.C. dismissed,  S.C.C.A. No. 329; Dionne v Ontario Hydro  O.J. No. 4337, Decision 1118/07).
The following excerpts give some indication of the Court's approach to Tribunal decisions on a Judicial Review and the appropriate degree of deference.
The Divisional Court stated in Quebec and Ontario Transportation Co. v. Otchere, (1992) O.J. No. 647, Decision 977/89:
"It is at the heart of this tribunal's specialized expertise to decide whether the worker's death resulted from an accident that arose out of and in the course of the worker's employment. It was open to the Appeals Tribunal to find that the act of moving from ship to dock, as the seaman did, was an activity reasonably incidental to the worker's employment."
In Tempelman v. Ontario (Workers' Compensation Appeals Tribunal) (1996), O.J. No.2097, Decision 82/93) the Divisional Court stated:
"In my view, by virtue of this privative clause of the Workers' Compensation Act, factual or legal determinations of the Tribunal made within its exclusive jurisdiction are immune from judicial review unless such determinations are so patently unreasonable as to require the intervention of the Court….
The W.C.A.T. is a tripartite specialist Tribunal. Therefore, it is entitled to deference in its interpretation of its constituent or home statute and its assessment of the facts in case before the Tribunal."
In Canada Post v Smith (supra) the Court of Appeal stated:
“The application of the compensation scheme for injured workers in Ontario, and, in particular, the determination of which provisions of the Workers' Compensation Act come within that scheme, are at the heart of the Board's and the Tribunal's specialized expertise. That expertise is entitled to deference Canada (Director of Investigation and Research) v. Southam Inc.,  1 S.C.R. 748 at p.775; C.U.P.E., Local 301 v. City of Montreal,  1 S.C.R. 793 at p.180)….
The Court of Appeal also stated:
"…The GECA is merely the statutory vehicle for transferring authority over these issues to the appropriate provincial bodies (s.4(3)), thereby inferentially absorbing all compensation-related rights and benefits provisions in provincial statutes (s.4(2)). As the expert body and designated interpreter of this legislation in Ontario, the Tribunal's decisions in this regard are entitled to curial deference absent clear irrationality.
No such irrationality is apparent either from the Tribunal's analysis or its conclusion in this case. Section 4(2) entitles injured federal employees to compensation under the same conditions as are available under provincial law. It is far from irrational or unreasonable to conclude that the right of re employment, found in s.54, is a fundamental condition of the entitlement to compensation in Ontario, an integral part of Ontario's compensation scheme, and therefore one of the benefits available as compensation in Ontario under s.4(2) of the GECA.
If the standard, however, is correctness, and I am wrong in concluding that the Tribunal's decision is entitled to curial deference based on its expertise and/or its jurisdictional hegemony, I am of the view, based on the foregoing analysis, that the Tribunal's decision is correct."
In Blue Line Taxi v WSIAT and Deek (2002) O.J. No.2036 (Div Ct), Decisions 934/98I and 934/98, the Divisional Court stated:
"The Tribunal is a specialized body protected by a strong privative clause (s.123 of the Act) and is entitled to curial deference in its interpretation of its constituent statute and assessment of the facts. The Court can interfere with the decision of the Tribunal if it is patently unreasonable. See: Ahmed v. Ontario (Workplace Safety and Insurance Appeals Tribunal)  O.J. No.2474 (Div. Ct.)."
In Wolverine Forest Products Ltd. v. Ontario (Workers' Compensation Appeals Tribunal) (1993), 64 O.A.C. 228 (Div. Ct.) the Court held that the question of deciding whether particular workers are independent contractors or workers lies at the heart of the functions performed by the Board.
In Chambers v. WSIAT (2002) O.J. No 4622, Decision 1902/01, the Court stated:
“The Tribunal is recognized by appellate authorities as a specialized Tribunal possessing expertise in issues relating to workplace issues, insurance law, and the effect of provisions of its constituent statute on a worker's right to sue….
The Tribunal's conclusion is informed by a complex mix of statutory concepts and entitlements with practical and policy factors which withstand a reasonably probing critique. It confirms the legislative intent that the decision is one properly left to the specialized Tribunal appointed to do so within the workers compensation scheme, unless its decision is patently unreasonable. The Tribunal's decision in this case is not a patently unreasonable one and is within its jurisdiction to make.”
In D & W Forwarders v. WSIAT (2003) O.J. No 5050, Decision 2185/01 the Divisional Court stated:
“The tribunal is a specialized body protected by a strong privative clause and is entitled to curial deference in the interpretation of its constituent statute and assessment of the facts. See Blue Line Taxi Co. v. Deek,  O.J. No. 2036 (Div. Ct.). Assessment and classification are at the heart of the tribunal's role and purpose. See Pasiechnyk v. Saskatchewan (Workers' Compensation Board),  2 S.C.R. 890.”
In Canada Post v Johnson (2004) O.J. No 63, Decisions 1480/98I and 1480/98:
“….The expertise of the provincial workers' compensation boards has been recognized in a number of judicial decisions: Pasiechniyk v. Saskatchewan (Workers' Compensation Board),  2 S.C.R. 890 at 913-914, Canada Post Corporation v. Smith (1998), 40 O.R. (3d) 97 (Ont. C.A.) at 106.
The purpose of the GECA as it applies to this case is to delegate to the Tribunal decisions as to the eligibility for compensation and the rate and conditions of compensation. The Tribunal is given broad discretion under the WCA and is required to base its decisions upon the real merits and justice of the case before it (WCA s. 73, 90, 92). It is a specialized tribunal which finds facts, decides questions of law and applies its understanding of the body of law, policy and jurisprudence that has developed around the workers' compensation system in Ontario. As stated in Pushpanathan, supra, at 1009, a statutory purpose that requires a tribunal to select from a range of remedial choices, is concerned with the protection of the public, engages policy issues, or involves a balancing of multiple sets of interests or considerations, will demand greater deference from a reviewing court.”
In Gowling v WSIAT and City of Hamilton (2004) O.J. No. 919, Decisions 255/02E, 255/02, 255/02R the Divisional Court stated:
”… appellate courts have applied a standard of patent unreasonableness when reviewing the decisions of the Workers' Compensation Board, the WSIAT, or its predecessor Workers' Compensation Appeals Tribunal. (See Meyer v. Waycon International Trucks Ltd. (1998), 38 O.A.C. 398 (C.A.); Consumers' Gas Co. v. Workers' Compensation Appeals Tribunal (1995), 87 O.A.C. 312 (Div. Ct.); and Chambers v. Ontario (Workplace Safety and Insurance Appeals Tribunal) (2002), 167 O.A.C. 101 (Div.Ct.). See also Ahmed v. Ontario (Workplace Safety and Insurance Appeals Tribunal,  O.J. No.2474 (Div.Ct.); and Blue Line Taxi Co. v. Deek,  O.J. No.2036 (Div. Ct.).)”
In Blue Line Taxi Co. v. Deek, the Divisional Court stated at para. 8  O.J. No.2036 (Div.Ct.):
“The Tribunal is a specialized body protected by a strong privative clause (s. 123 of the Act) and is entitled to curial deference in its interpretation of its constituent statute and assessment of the facts. The Court can interfere with the decision of the Tribunal if it is patently unreasonable.
As we view the material filed and the submissions, the respondents' position is that the matter of the applicant's entitlement to FEL benefits falls within the Tribunal's exclusive jurisdiction, and determination of the Tribunal made within its exclusive jurisdiction are immune from judicial review unless such determinations are so patently unreasonable as to require the intervention of the court.
In our view the appeal decision of Vice-Chair E.J. Smith, which hearing was completed on July 8, 2002, is a comprehensive consideration of the matters before her with a detailed analysis of the issues.
In our view it may not be held to be patently unreasonable.
As to the denial of natural justice, we are of the view that there is, on the material before us, no basis for such a finding.”
In Ottawa Hospital v Meyer and WSIAT (June 15 2004), unreported, Divisional Court, Decisions 28/02, 28/02R, the Court stated:
"The WSIAT is a specialized Tribunal with broad expertise in WSIB matters, and its decisions are protected by a privative clause. It is entitled to great deference."
In Roach v. Ontario (Workplace Safety and Insurance Appeals Tribunal)  O.J. No. 1295, Decision 770/98IR, leave to appeal to S.C.C. dismissed  S.C.C.A. No.264 (QL), the Court of Appeal stated:
“The parties agreed, and the Divisional Court held, that the standard of review for the Tribunal’s reconsideration decision was patent unreasonableness. We agree.
The patent unreasonableness standard of review is "clearly a very strict test": see Canada (Attorney General) v. Public Service Alliance of Canada,  1 S.C.R. 941 at 964 ("PSAC"). A tribunal's decision should be set aside as patently unreasonable only if it is "clearly irrational, that is to say evidently not in accordance with reason" or "so flawed ... that no amount of curial deference can properly justify letting it stand": see, respectively, PSAC at pp. 963-64 and C.U.P.E. v. Ontario (Minister of Labour),  1 S.C.R. 539 at para. 165.
With respect, I am of the view that the Divisional Court erred in its conclusion that the Tribunal’s reconsideration was so flawed that it met this exacting standard and deserved to be quashed….
….The Tribunal carefully considered all the evidence and reached, and explained, its decision. In short, the Tribunal did precisely what it was supposed to do.
…I conclude that the Divisional Court erred in determining that the Tribunal’s reconsideration decision was patently unreasonable.
I would allow the appeal, set aside the decision of the Divisional Court and reinstate the final decision of the Tribunal.”
In Rodrigues v. Ontario (Workplace Safety & Insurance Appeals Tribunal) (2008)92 O.R. (3d) 757,which was decided after the Supreme Court of Canada decision in Dunsmuir v. New Brunswick, the Court of Appeal stated:
“Although the Supreme Court of Canada in Dunsmuir v. New Brunswick,  1 S.C.R. 190,  S.C.J. No. 9, 2008 SCC 9 collapsed the patent unreasonableness and simpliciter standard of review into a single form of an unreasonableness standard, the Supreme Court appears to say that it is not necessary to engage in a fresh standard of review analysis in decisions made before Dunsmuir. This would mean that the standard of review in this case would remain patent unreasonableness. …. Whether the standard of review is patent unreasonableness or unreasonableness, existing jurisprudence shows that reviewing courts can interfere only where in the case of patent unreasonableness where the Tribunal's decision is "clearly irrational", and in the case of unreasonableness where the decision does not fall within a range of possible, acceptable outcomes. To interfere, the reviewing court must find that there are no lines of reasoning supporting the decision that could have reasonably led the tribunal to reach the decision that it did.
….It would appear that no court has ever interfered with any of the thousands of decisions of the Tribunal concerning an employee's pre-accident earnings. This is no doubt due to the substantial degree of deference accorded to the Tribunal based on the legislature's decision to create the Board and the Tribunal, to vest in the Board the exclusive authority to calculate a worker's pre-accident earnings, to delegate to the Tribunal the exclusive authority to review matters of workplace safety and insurance, to appoint to the Board and Tribunal members who are experienced in issues of workers' compensation, and to protect the Board and the Tribunal with the toughest privative clause known to Ontario law. The privative clause is most important as it evidences a legislature's intent that an administrative decision maker be given greater deference and that interference by reviewing courts be minimized: Dunsmuir, at paras. 45 and 48. Thus, reviewing courts can interfere only where the Tribunal's decision is clearly irrational.”