United Association of Canada v. Labourers' International Union of North America, Local 1059, 2026 ONSC 18

CITATION: United Association of Canada v. Labourers' International Union of North America, Local 1059, 2026 ONSC 18

DIVISIONAL COURT FILE NO.: 342/25-JR

DATE: 20260102

ONTARIO

SUPERIOR COURT OF JUSTICE

DIVISIONAL COURT

Backhouse, Lococo and Kaufman, JJ.

BETWEEN:

UNITED ASSOCIATION OF CANADA, UNITED ASSOCIATION OF JOURNEYMEN AND APPRENTICES OF THE PLUMBING AND PIPEFITTING INDUSTRY OF THE UNITED STATES AND CANADA, LOCAL 853 and UNITED ASSOCIATION OF JOURNEYMEN AND APPRENTICES OF THE PLUMBING AND PIPEFITTING INDUSTRY OF THE UNITED STATES AND CANADA, LOCAL 527

Applicants

– and –

LABOURERS' INTERNATIONAL UNION OF NORTH AMERICA, LOCAL 1059 and LABOURERS' INTERNATIONAL UNION OF NORTH AMERICA, ONTARIO PROVINCIAL DISTRICT COUNCIL, TROY LIFE & FIRE SAFETY LTD., E.S. FOX LIMITED and ONTARIO LABOUR RELATIONS BOARD

Respondents

COUNSEL:

Doug Wray and Erin Carr for Applicants

Kristaq Lala and Hong Hua (Emily) Li, for the union Respondents

Herbert H. Law and Anthony Kwong, for the Respondent Troy Life & Fire Safety Ltd.

Aaron Hart, for the Respondent Ontario Labour Relations Board

HEARD at Toronto: December 11, 2025

Backhouse J.

Overview

[1] The Applicant union (“UA”) seeks judicial review of two decisions (the “Decisions”) of the Ontario Labour Relations Board (the “Board”) dealing with a jurisdictional dispute between two unions. The Board determined that the installation of a new water-based fire suppression system which had been assigned to UA by Troy Life & Fire Safety Ltd. (“Troy”) was within the jurisdiction of the Labourers (“LIUNA”).

[2] UA supported by Troy argue that the Board failed to consider the requirements under the Building Opportunities in the Skilled Trades Act, 2021, S.O. 2021, c. 28 (“BOSTA”) which they argue created exclusive jurisdiction in favour of UA’s members. They submit that based on the failure of the Board to justify its conclusion that this legislation is irrelevant, the Decisions were unreasonable. UA and Troy ask that the Decisions be quashed and that the matter be remitted to a different Vice-Chair of the Board.

[3] The Board found that BOSTA’s purpose is to protect the public by determining the skill set necessary for work performed by regulated trades, not to determine trade jurisdiction or to override the traditional factors considered in a jurisdictional dispute which it found favoured LIUNA with respect to the disputed installation work.

[4] LIUNA argues that the Board’s decisions were reasonable and the application should be dismissed.

[5] For the reasons set out below, I would dismiss the application.

Background

[6] LIUNA filed a jurisdictional dispute under s. 99 of the Labour Relations Act, 1995, S.O. 1995, c. 1, Sched. A against UA representing plumbers and pipefitters. Section 99 of the Labour Relations Act does not set out any factors or criteria which the Board must (or might) consider in determining a jurisdictional dispute. Section 99(5) states:

99(5) The Board may make any interim or final order it considers appropriate after consulting with the parties.

[7] The work in dispute was being performed at the Bruce “A” site of the Bruce Nuclear Power Development. It involved:

a. the dismantling and removal of the plumbing of an old water-based fire suppression system, which E.S. Fox Limited (“E.S. Fox”) assigned to members of the UA; and

b. the installation of a new water-based fire protection system which E.S. Fox subcontracted to Troy who assigned the work to members of the UA.

[8] In its decision dated February 20, 2025 reported at 2025 20783 (ON LRB), the Board affirmed E.S. Fox’s work assignment to members of the UA regarding removal of the old fire watermain system but overturned Troy’s work assignment with respect to the installation portion of the disputed work and found it was in the jurisdiction of LIUNA (the “Original Decision”).

[9] In its reconsideration decision dated April 2, 2025, reported at 2025 39837 (ON LRB), the Board dismissed the arguments made by UA and Troy on reconsideration (the “Reconsideration Decision”). Only the installation work is in issue dispute on this judicial review.

The Original Decision

[10] The Board assessed the jurisdiction of each trade to perform the disputed work and made the following findings based on the six well-known factors established over decades of Board jurisprudence applied in work assignment disputes:

a. collective agreements – the Board found the work could fall within the scope of both unions’ collective agreements;

b. trade agreements between competing unions – the Board found there are no relevant trade agreements;

c. employer practice – the Board found there was not enough relevant practice evidence to make a determination on this factor;

d. area practice – LIUNA was able to present significantly more historical evidence of their members performing this type of work within the geographic area, and therefore the Board found this factor to heavily favour the Labourers;

e. safety skills and training – the Board found both parties demonstrated that their members have the skills and training required to perform the work safely; and

f. economy and efficiency – the Board found neither trade demonstrated that it would be more economical or efficient for the work to be performed by its members.

[11] Under the arguments focused on “safety skills and training”, UA and Troy raised BOSTA, arguing that its provisions and the regulations thereunder set out the tasks that are part of the trade of “sprinkler fitter”. They argued that it is highly relevant that the Legislature determined that only certified sprinkler fitters can safely perform the work in dispute, and that the disputed work falls within the core jurisdiction of a sprinkler fitter. In its Brief, UA stated:

While the UA recognizes that the factors employed by the Board by jurisdictional disputes are not per se governed by the BOSTA regulations, the UA submits that it is highly relevant that the Legislature determined that only certified sprinkler fitters, who have been trained in concordance with NFPA 24, can safety (sic) perform the work in dispute.

[12] The Board concluded that BOSTA should not be relied on to determine competing work jurisdiction issues, citing earlier Board jurisprudence to demonstrate the Board has long resisted the application of apprenticeship and qualification legislation to these types of disputes.

[13] In the Original Decision at para. 90, the Board dealt with the BOSTA issue as part of its consideration of the Safety, Skills and Training factor as follows:

90. The Board has previously held that the Building Code was not intended to divide work jurisdiction between competing construction trade unions, and that it does not purport to do so: see Bruce Power LP, 2006 33923 (ON LRB) at para. 29. Furthermore, the UA has tried, on a number of occasions, to persuade the Board that qualification and apprenticeship legislation ought to be relied on by the Board to find that certain work falls exclusively within its trade for the purposes of a work assignment dispute. The Board consistently resists the UA’s entreaty to do so. For example, the Board found in E.S. Fox, [1989] OLRB Rep. July 738 that the relevant legislation in force at the time of that decision, the Apprenticeship Act, did not provide any trade, even a compulsory certified trade, with an exclusive trade jurisdiction. The Board in Bruce Power LP, supra, adopted the reasoning in E.S. Fox, supra, in its entirety and similarly found that the relevant legislation in force at the time of that decision, the Trades Qualification and Apprenticeship Act, R.S.O. 1990, c.T.17 did not grant exclusive jurisdiction over rigging work to any one trade. The Board, in the case before it here, similarly holds the view that the current legislation, BOSTA, similarly, ought not to be relied on to determine competing work jurisdiction issues.

[14] The Board found an absence of evidence that the disputed work fell within the exclusive jurisdiction of the UA. Rather, it found there was significantly more historical evidence of LIUNA’s members performing the installation type of work within the geographic area. While the other factors it considered were either neutral or inapplicable, the “area practice” factor – typically weighed most heavily by the Board – strongly favoured the LIUNA with respect to the installation portion of the disputed work and to whom the Board assigned the work.

Reconsideration Decision:

[15] Both UA and Troy applied for reconsideration of the Original Decision, raising largely the same arguments as are made on judicial review. Specifically, they emphasize that BOSTA’s compulsory jurisdiction provisions should have been taken into account. They claimed that the Board relied on distinguishable jurisprudence and that it is impossible to comply with both BOSTA and the Decisions.

[16] The Board rejected these arguments, finding that this was a much stronger stance on BOSTA than UA or Troy had taken at the initial hearing. It emphasized that the factor for consideration is whether members of each trade can perform the work safely, and the Board had considered this factor and found that it was neutral. It went on to dismiss UA and Troy’s concerns about the impossibility of compliance based on the fact that LIUNA members often performed this type of work in the past, without any complaints under BOSTA. Finally, it reemphasized that the purpose of BOSTA is to protect the public by determining the skill set necessary for compulsory regulated trades, not to override the Board’s traditional factors in work assignment disputes.

Issue

[17] The only issue raised on judicial review is whether the Board’s failure to consider the terms of BOSTA renders the Decisions unreasonable.

Court’s Jurisdiction and Standard of Review

[18] Section 116 of the Labour Relations Act provides that orders of the Board are not subject to judicial review. Nevertheless, this court has jurisdiction to hear the application pursuant to ss. 2 and 6 of the Judicial Review Procedure Act, R.S.O. 1990, c. J.1.

[19] The presumptive standard of review for all questions on judicial review is reasonableness, per Canada (Minister of Citizenship and Immigration) v. Vavilov, 2019 SCC 65, [2019] 4 S.C.R. 653, at para. 25. None of the exceptions to this presumption are present in this case: see Turkiewicz (c.o.b. Tomasz Turkiewicz Custom Masonry Homes) v. Bricklayers, Masons Independent Union of Canada, Local 1, 2022 ONCA 780, 476 D.L.R. (4th) 421, at para. 53, leave to appeal refused, [2023] S.C.C.A. No. 131; Enercare Home & Commercial Services Limited Partnership v. UNIFOR, Local 975, 2022 ONCA 779, 476 D.L.R. (4th) 342, at para. 42, leave to appeal refused, [2023] S.C.C.A. No. 133.

[20] While all parties agree that reasonableness is the appropriate standard of review, LIUNA argues that UA’s framing of its reasonableness review, in reality, amounts to a request for the correctness standard which is considered below.

Issue 1: Did the Board’s failure to consider the terms of BOSTA render the decision unreasonable?

[21] UA makes the following submissions:

a) BOSTA is a relevant legal constraint that was put before the Board in the Original Decision, and the Board failed to justify its conclusion that BOSTA is irrelevant to jurisdictional disputes.

b) Vavilov requires decisions to comply with legal and factual constraints. The requirement to consider statutes of general application has been long accepted. BOSTA is a statute of general application that, along with the regulations, defines the scope of work of sprinkler fitters as a compulsory trade to include the installation of water-based fire protection systems. The work at issue falls squarely within this definition.

c) Even if the Board was not required to comply with BOSTA, it failed to provide a coherent explanation for dismissing it. It did not engage with BOSTA itself, or why it should or should not be applied to the present dispute.

d) Both cases cited by the Board referred to repealed, predecessor legislation to BOSTA. BOSTA introduced a new, more codified and direct statutory and regulatory structure of core prohibitions. The Board failed to acknowledge this legislative change, or to even analyze BOSTA itself.

e) The cases relied upon are distinguishable because E.S. Fox[^1] was a certification, not a jurisdictional dispute, and Bruce Power[^2] referred to a different type of work that was not as clearly covered by the legislation.

f) The Board further failed to justify its departure from jurisprudence holding that where work falls within the “core jurisdiction” of a given trade, that fact must be given weight in a jurisdictional dispute. BOSTA defines the core jurisdiction of sprinkler fitters and yet this is not meaningfully considered, nor is any explanation provided for why it is ignored. The Board also ignored its finding in Bruce Power and E.S. Fox that laws of general application must be complied with, and while the legislation in those cases was not found to confer “exclusive jurisdiction” neither was it ignored altogether. The Board’s outright rejection of BOSTA as irrelevant was inconsistent with the jurisprudence of the Board itself, and the Supreme Court of Canada.[^3]

g) By ignoring BOSTA the Board has created a legally incoherent result. The Board’s decision requires LIUNA members to install a fire watermain system. Yet BOSTA specifically requires certified or apprenticed sprinkler fitters to perform that work. Contractors will not be able to comply with both these legal requirements. The Board claims that because there is no evidence confirming “exclusive jurisdiction” the conflict need not be resolved. Yet it was not argued that BOSTA creates exclusive jurisdiction. Rather it creates a compulsory trade certification regime that restricts the lawful performance of certain work to certified or apprenticed individuals.

h) The Board attempts to justify these conflicting results because there have not yet been complaints filed under BOSTA, and LIUNA members have previously performed this type of work This does not erase the requirement to comply with government legislation. This is especially unjustified where the purpose of raising BOSTA in this context was to challenge the assumption that past assignments were lawful. The Board has created precisely the legal uncertainty that Vavilov warns against.

Analysis

[22] Section 99 of the Labour Relations Act assigns a broad jurisdiction to the Board in the resolution of jurisdictional disputes. The Board is empowered to make “any interim or final order it considers appropriate”. Section 99 reflects a legislative policy that disputes over work jurisdiction should be resolved by a decision of the Board, rather than by economic conflict.

[23] The courts have a long-standing jurisprudential commitment to affording labour relations decision makers the highest degree of deference. As noted by the Court of Appeal for Ontario in Maystar General Contractors Inc. v. International Union of Painters and Allied Trades, Local 1819, 2008 ONCA 265, 90 OR (3d) 451, at para. 42:

The decisions of the Supreme Court of Canada, over the course of many decades, show an unbroken commitment to affording labour relations boards the highest levels of judicial deference on matters within their exclusive jurisdiction.

[24] The Court of Appeal emphasized in Turkiewicz, at para. 77 and Enercare, at para. 64, speaking specifically about the Board, that it is a highly specialized tribunal with considerable expertise, placing it in an elevated position to interpret its home statute. Additionally, construction labour relations has been singled out as an area of particular expertise, attracting particular judicial deference. In International Brotherhood of Electrical Workers, Local 1739 v. International Brotherhood of Electrical Workers (2007), 2007 65617 (ON SCDC), 86 O.R. (3d) 508 (Div. Ct.), at para. 47, the Divisional Court described the Board’s construction industry oversight as follows: “not only was the Board acting in its area of general expertise, but it was also acting in a doubly specialized capacity relating to the construction sector, an area of responsibility it was entrusted to regulate in accordance with industry-specific legislative rules. The Divisional Court has followed this recognition in subsequent cases: see Brookfield Multiplex Construction Canada Limited v. Labourers' International Union of North America, 2018 ONSC 548 (Div. Ct.), at para. 20; RT HVAC Holdings Inc. v. United Association of Journeymen and Apprentices of the Plumbing and Pipefitting Industry of the United States and Canada, 2023 ONSC 6066 (Div. Ct.), at para. 26.

[25] At paras. 30-32 of its factum, UA argues that the first step in a reasonableness review is to determine the relevant legal and factual constraints, apparently before considering the tribunal’s reasons. It describes this step as an “objective, binary determination”.

[26] This is incorrect and inconsistent with Vavilov and the cases that have followed and interpreted it, and particularly the Court of Appeal’s decision in Enercare and the Ontario decisions that have followed Enercare. Vavilov emphasized, as noted above, that in order to determine whether a decision is reasonable, the reviewing court must “develop an understanding of the decisions maker’s reasoning process”, and “examine the administrative decision as a whole”: Vavilov, at paras. 99 and 116, and also at para. 122 with respect specifically to a tribunal’s analysis of a statutory provision.

[27] In Enercare, at paras. 72-73, the Court of Appeal applied this analysis in considering the Divisional Court’s decision below, and identified the analytic error as follows:

[72] First, a reasonableness review requires an initial consideration of the Board Decision as a whole, to determine if the decision bears the requisite level of intelligibility, transparency, and justification. The reviewing court must consider only whether the decision – both the rationale for it and the outcome to which it led – is unreasonable (Vavilov, at paras. 84-86). It is not to undertake a de novo analysis but, rather, it must “examine the administrative decision as a whole, including the reasons provided by the decision maker and the outcome that was reached” (para. 116).

[73] The Divisional Court did not follow this approach when it reviewed the Board Decision. Instead, it considered the legislative history of s. 1(4) and the OLRB jurisprudence on it and came to its own determination of what was required for the Board to make a related employer declaration. Its view was that it was necessary for the parties’ bargaining history, collective agreement, and other agreements respecting contracting out to be considered when determining whether the s. 1(4) preconditions to a declaration had been met. Because the Board had not done that, according to the Divisional Court, the Board Decision was unreasonable. However, as the Federal Court of Appeal aptly put it, “as reviewing judges, we do not make our own yardstick and then use that yardstick to measure what the administrator did”: Delios v. Canada (Attorney General), 2015 FCA 117, 472 N.R. 171, at para. 28; Vavilov, at para. 83. Instead of following the Vavilov approach, the Divisional Court made its own yardstick and measured the Board Decision against it.

[28] Accordingly, this court should not “first assess whether a particular factual or legal constraint is relevant” and then assess the tribunal’s reasons, as posited by the UA. This is a request that the court “make its own yardstick” and then “measure” a tribunal’s decision against it.

[29] In Turkiewicz, the Court of Appeal has also underlined the relevance of the expertise of the administrative decision maker, having particular regard to the Board and statutory interpretation. The Court of Appeal held at para. 61:

[61] I would add that the reviewing court must bear in mind the expertise of the administrative decision maker with respect to the questions before it. At para. 31 of Vavilov, the Supreme Court states that “expertise remains a relevant consideration in conducting [a] reasonableness review.” Being attentive to a decision maker’s demonstrated expertise may reveal to a court why a decision maker reached a particular outcome or provided less detail in its consideration of a given issue (para. 93). Moreover, decision makers’ specialized expertise may lead them to rely, when conducting statutory interpretation, on “considerations that a court would not have thought to employ but that actually enrich and elevate the interpretive exercise” (para. 119). As such, relevant expertise of the administrative decision maker must be borne in mind by a court conducting a reasonableness review, both when examining the rationality and logic of the decision maker’s reasoning process and the decision itself, in light of the factual and legal constraints bearing on it.

[30] UA submits that it did not argue before the Board that BOSTA was determinative of the dispute. Rather, it argued that BOSTA, by determining that only certified sprinkler fitters can safely perform the work in dispute, is highly relevant to the factors considered by the Board in a jurisdiction dispute. In substance, however, UA’s argument is that BOSTA was not given sufficient weight in the Board’s discretionary analysis. It is noteworthy that the Board found that in weighing the safety skills and training factor, both parties demonstrated that their members have the skills and training to perform the work safely. It is not the role of this court in conducting a judicial review to rebalance the weight that should be put on BOSTA.

[31] The Board has consistently found that qualification and apprenticeship legislation is safety legislation which is not intended to divide work jurisdiction between competing construction trade unions. At para. 39 of the Reconsideration Decision the Board stated:

39. It bears repeating that one of the purposes of BOSTA, like the legislation that preceded it, is to protect the public by determining the skill set necessary for work performed by compulsory regulated trades. Its purpose is not to determine trade jurisdiction between competing construction trade unions: see E.S. Fox Limited, [1989] OLRB Rep. July 738 and Bruce Power LP, 2006 33923 (ON LRB). Despite the urging of the UA and Troy to the contrary, the Board does not agree that BOSTA operates to override the traditional factors which the Board considers in a work assignment dispute.

[32] UA submits that it was not arguing that BOSTA creates exclusive jurisdiction. However, it fails to explain how its argument that BOSTA creates a compulsory trade certification regime that restricts the lawful performance of the work in question to its certified or apprenticed sprinkler fitters differs from an argument that BOSTA creates exclusive jurisdiction.

[33] With respect to UA’s argument that the Board failed to provide any rationale for relying on distinguishable cases under repealed statutes, UA acknowledged in its submissions before this court that there was not a significant difference between the prior legislation, the Trades Qualification and Apprenticeship Act R.S.O. 1990, c. T.17 (repealed), and BOSTA.

[34] Despite UA’s submission that the cases relied upon by the Board are distinguishable, UA does not dispute the Board’s finding in para. 90 of the Original Decision that the Board has consistently held that qualification and apprenticeship legislation cannot be relied on to determine that certain work falls exclusively within a trade for the purposes of a work assignment dispute. UA acknowledged in the Brief it submitted to the Board that it recognizes that the factors employed by the Board in jurisdictional disputes are not per se governed by the BOSTA regulations.

[35] The Board did not fail to explain why it declined to treat BOSTA as relevant to the jurisdictional dispute. It found that BOSTA’s purpose is to protect the public by identifying the skills required for compulsory regulated trades. It does not displace the Board’s established factors for resolving work‑assignment disputes between unions.

[36] At para. 91 of the Original Decision, the Board found, based on the evidence before it, that members of the LIUNA had performed the disputed installation work at Bruce Nuclear Power Development on numerous occasions without any safety concerns and without being advised by the Ministry of Labour that they were not permitted to do so. Given the evidence demonstrating that members of both the LIUNA and the UA had the skills and training to perform the disputed work safely, it determined that the “safety, skills and training” factor was neutral.

[37] With respect to the UA’s argument that the disputed work falls within the core jurisdiction of its trade, the Board found that the UA has not been able to provide the Board with a significant amount of practice evidence to suggest that work similar to the work in dispute is consistently or regularly performed by its members.

[38] Based on the six established factors the Board considered in assessing the jurisdiction of each trade to perform the disputed work, they were all neutral with the exception of the factor: “area practice”, that is the practice evidence of who had been performing the work. The Board found that the LIUNA had eight projects in their favour and the UA had one project, which was accorded some, although lesser, weight.

[39] Contrary to the UA’s allegation, the Board did consider the parties’ arguments regarding the NFPA 24 certification. The Board reviewed all of the evidence and argument before it that related to this factor at paras. 76-87 of the Original Decision, including the parties’ arguments about the NFPA 24 certification and its significance. As indicated in paras. 91-93, the Board’s conclusion in respect of this factor considered all of those arguments. Ultimately, the Board concluded that based on the evidence filed and the arguments the parties made, both the LIUNA and the UA have demonstrated that their respective members have the skills and training to perform the work in dispute safely.

[40] As noted above, the Board found an absence of evidence that the installation portion of the disputed work fell within the exclusive jurisdiction of the UA. Rather, it found that LIUNA’s members and not UA’s members had been performing the vast majority of this type of work historically within the geographic area. While the other factors it considered were either neutral or inapplicable, who had been doing the work historically strongly favoured the LIUNA and to whom the Board assigned the work.

The Board’s Treatment of the BOSTA Argument

[41] On reconsideration, the UA and Troy both take the position that the Board erred when it held that BOSTA ought not to be relied on to determine competing work jurisdiction issues. The Board held that it is important to note the positions that the UA and Troy took in their Consultation materials filed with respect to the Original Decision. After discussing how it believed BOSTA applied to the work in dispute, Troy took the position that the collective bargaining relationships factor either favoured the assignment of the work in dispute to the UA or, alternatively, that the factor is neutral. The Board agreed with Troy that the factor is neutral. As noted above, after discussing BOSTA within its analysis on the skills, safety and training factor, the UA acknowledged that the factors employed by the Board in jurisdictional disputes are not governed by the BOSTA regulations, although it submitted that it was highly relevant that the Legislature determined that only certified sprinkler fitters can safely perform the work in dispute.

[42] The Board considered the positions of the UA and Troy, as well as the position of LIUNA that its members can and have performed this work safely and, seemingly, without being advised by the Ministry of Labour or any other entity that they were not permitted to do so (whether under BOSTA or any other legislation).

[43] The Board’s determination in its Original Decision was based on the materials before it and the positions taken by the parties. UA and Troy did not argue at that time that BOSTA was determinative of the issue, and the Original Decision is reasonable and owed significant deference.

[44] Despite UA and Troy not arguing at the time of the Original Decision that BOSTA was determinative of the issue, on reconsideration, the Board considered UA’s revised position, now characterizing BOSTA as establishing “compulsory jurisdiction” and arguing that employers had been placed in a conflict between complying with BOSTA and honouring past practice. The Board rejected this, finding that this was not BOSTA’s purpose.

[45] In the Reconsideration Decision, the Board reasonably found that the fact that the UA and Troy disagree with how the Board made its determination is not an appropriate ground for reconsideration, particularly given the positions each took in their materials. The Board’s Original Decision cannot be found unreasonable for not responding to arguments not made.

[46] The Board went on to make the following comments on the new submissions Troy and UA made on Reconsideration:

37. Both Troy and the UA submit that the Decision will place employers in a difficult position where they must choose between complying with BOSTA and honouring past practice when assigning similar work in the future. However, neither Troy nor the UA provided the Board with any evidence confirming a finding that the installation portion of the work in dispute falls within the exclusive jurisdiction of members of the UA. Furthermore, similar work has been performed in the past by members of the Labourers after BOSTA came into force, apparently without any complaint that BOSTA had been violated.

38. It bears repeating that one of the purposes of BOSTA, like the legislation that preceded it, is to protect the public by determining the skill set necessary for work performed by compulsory regulated trades. Its purpose is not to determine trade jurisdiction between competing construction trade unions: see E.S. Fox Limited, [1989] OLRB Rep. July 738 and Bruce Power LP, 2006 33923 (ON LRB). Despite the urging of the UA and Troy to the contrary, the Board does not agree that BOSTA operates to override the traditional factors which the Board considers in a work assignment dispute.

[47] The weight that the Board gave to BOSTA and its finding that BOSTA does not operate to override the traditional factors that the Board considers in a work assignment dispute are construction labour relations matters that have been singled out as an area of particular expertise, attracting particular judicial deference. Bearing in mind the specialized knowledge, institutional expertise and experience of the Board, the rationale of the Decisions and their outcome as a whole bear the requisite level of intelligibility, transparency and justification. The Decisions demonstrate a coherent and rational connection between the relevant facts, the outcome of the Decisions and the reasoning process that led the Board to that outcome. There is no basis on which this court should intervene.

Costs

[48] In accordance with the parties’ agreement, LIUNA as the successful party is entitled to costs of $5,000 from UA and $5,000 from Troy.

Backhouse J.

I agree _______________________________

Lococo J.

I agree _______________________________

Kaufman J.

Released: January 2, 2026

[^1]: United Association of Journeymen and Apprentices of the Plumbing and Pipefitting Industry of the United States and Canada, Local 527 v. Bruce Power LP, 2006 33923 (ON LRB), at paras. 29-30.

[^2]: International Association of Heat and Frost Insulators and Asbestos Workers, Local 95 v. E.S. Fox Limited, 1989 3060 (ON LRB), at para 8.

[^3]: Paul v. British Columbia (Forest Appeals Commission), 2003 SCC 55, [2003] 2 S.C.R. 585; and Parry Sound (District) Social Services Administration Board v. Ontario Public Service Employees Union, Local 324 (O.P.S.E.U.), 2003 SCC 42, [2003] 2 S.C.R. 157.