COURT OF APPEAL FOR BRITISH COLUMBIA
British Columbia Teachers’ Federation v. British Columbia,
2012 BCCA 326
British Columbia Teachers’ Federation
British Columbia Public School Employers’ Association
The Honourable Madam Justice Prowse
The Honourable Madam Justice Garson
The Honourable Mr. Justice Hinkson
On appeal from: Arbitration
award pursuant to the Labour Relations Code,
R.S.B.C. 1996, c. 244, May 18, 2011 (British Columbia Public School Employers’ Association v. British Columbia Teachers’ Federation)
Counsel for the Appellant:
C. Allevato & C.D. Bavis
Counsel for the Respondent:
Place and Date of Hearing:
Vancouver, British Columbia
February 16 and 17, 2012
Place and Date of Judgment:
Vancouver, British Columbia
August 3, 2012
Written Reasons by:
The Honourable Madam Justice Garson
Concurred in by:
The Honourable Madam Justice Prowse
Reasons for Judgment of the Honourable Madam Justice Garson:
 The British Columbia Teachers’ Federation (“BCTF”) appeals from the May 18, 2011 decision of Arbitrator Dorsey. The arbitrator’s decision is cited as  B.C.C.A.A.A. No. 58. As will be explained below, that decision follows and is related to another made by the arbitrator (see  B.C.C.A.A.A. No. 81). I will (as did the parties on appeal) refer to the 2009 and 2011 arbitration awards as the First Representative Decision and Second Representative Decision, respectively.
 This appeal concerns the arbitrator's interpretation of certain of the class size and composition provisions of the School Act, 1996 R.S.B.C., c. 412. The appellant takes issue with the manner in which the arbitrator assigned the burden of proof in grievances alleging breach of the class size and composition standards created by ss. 76.1(2.2) and (2.3). It also appeals the arbitrator’s related decision to create a formula (“the Rule of 33”). He decided that if a class did not exceed 33 (calculated by adding the number of students in the class and the number of students with individual educational plans or IEP’s), he would accord presumptive deference to the opinions of the principal and superintendent that the class was appropriate for student learning. This meant that, for classes that did not exceed the Rule of 33 but did exceed the statutory class size and composition requirements, the burden was on the teacher, the grievor, to rebut the presumption of deference to the principal and superintendant opinions that the class is appropriate for student learning.
 As will be explained in greater detail below, the respondent characterizes the legislation as the setting of flexible standards and contends that the arbitrator’s use of the Rule of 33 fits within the legislative scheme. As to the assignment of the burden, the respondent contends that it is the grievor who asserts the claim and “he who asserts” must prove his claim.
 The respondent also notes that the arbitrator developed the Rule of 33 in his first decision and that decision was not appealed. It says that the parties relied on and applied the rulings from the first decision in subsequent processes and proceedings and thus the appellant cannot now advance a ground of appeal which is in essence an appeal of the first decision. It also says that the evidential and legal burden were not in issue in the decision under appeal and so cannot be the basis for a ground of appeal of the 2011 arbitration. Thus, the respondent argues that this Court ought not to accede to the appeal.
 This appeal marks a further development in the decades-long conflict over classroom organization. The present statutory scheme attempts to ease the tension between the desire of teachers to teach classes of manageable size and composition and the school administrators’ need for a degree of flexibility in meeting broader demands on resources. One can easily sympathize with both points of view. The legislative scheme sets class organization limits and grants school administrators latitude to exceed those limits for a given class if doing so does not compromise student learning. It is evident from the sheer volume of grievances that school administrators frequently found it necessary to exceed the statutory limits. The arbitrator struggled to find a principled way to manage the daunting volume of grievances. But, as I explain, his decision resulted in the creation of a group of classes that exceeded the statutory limits but which were partially insulated from arbitral scrutiny over the question of suitability for student learning.
 It may well be that the arbitrator was of the view that many of the grievances ought to be dealt with summarily because the degree to which those class exceeded the statutory limits was modest. Possibly the parties could, in the future, with some collaborative good faith effort, develop a procedural accommodation that might permit a more streamlined process. But the one chosen by the arbitrator was an impermissible supplementation of the statute.
 As is explained at the conclusion of this judgment, I would allow the appeal and set aside the arbitrator’s decision, subject to the parties’ agreement not to disturb the outcome of grievances that predate September 2010.
A. Legislative Background and Provisions
 By 2002 amendments to the School Act, class size and class composition limits could no longer be the subject of collective bargaining. The amendments prohibited a collective agreement between BC teachers and their employers from including terms relating to class size or composition (see s. 27(3) of the School Act). On April 13, 2011, the British Columbia Supreme Court declared this prohibition unconstitutional (British Columbia Teachers’ Federation v. British Columbia, 2011 BCSC 469). The parties acknowledge that the judgment does not directly impact the arbitration that is now under appeal.
 The sections of the School Act that are pertinent to this appeal create statutory class size and composition standards. Below, I set out a brief summary explanation of the relevant sections followed by the full text of the applicable sections.
 The class size limits operate as follows:
· Kindergarten - may not exceed the class size limit of 22 in any case;
· Grades 1 to 3 - may not exceed the class size limit of 24 in any case;
· Grades 4 to 7 - may not exceed the class size limit of 30 unless the teacher gives consent and the principal and superintendent form the opinion the class is appropriate for student learning; and
· Grades 8 to 12 – may not exceed the class size limit of 30, unless the principal consults with the teacher and the principal and superintendent form the opinion the class is appropriate for student learning.
 The class composition limit operates as follows:
· A class in any grade may not exceed the class composition limit, that is more than 3 students with an IEP, unless the principal consults with the teacher and the principal and superintendent form the opinion the class is appropriate for student learning.
ii. Statutory Sections
76.1 (1) A board must ensure that the average size of its classes, in the aggregate, does not
(a) for kindergarten, 19 students,
(b) for grades 1 to 3, 21 students,
(c) for grades 4 to 7, 28 students, and
(d) for grades 8 to 12, 30 students.
(2) Despite subsection (1), a board must ensure that the size of any primary grades class in any school in its school district does not exceed
(a) for kindergarten, 22 students, and
(b) for grades 1 to 3, 24 students.
(2.1) Despite subsection (1) but subject to subsection (2.4), a board must ensure that the size of any class for any of grades 4 to 7 in any school in its school district does not exceed 30 students unless
(a) in the opinions of the superintendent of schools for the school district and the principal of the school, the organization of the class is appropriate for student learning, and
(b) the principal of the school has obtained the consent of the teacher of that class.
(2.2) Despite subsection (1) but subject to subsection (2.4), a board must ensure that the size of any class for any of grades 8 to 12 in any school in its school district does not exceed 30 students unless
(a) in the opinions of the superintendent of schools for the school district and the principal of the school, the organization of the class is appropriate for student learning, and
(b) the principal of the school has consulted with the teacher of that class.
(2.3) Despite subsections (1) to (2.2) but subject to subsection (2.4), a board must ensure that any class in any school in its school district does not have more than 3 students with an individual education plan unless
(a) in the opinions of the superintendent of schools for the school district and the principal of the school, the organization of the class is appropriate for student learning, and
(b) the principal of the school has consulted with the teacher of that class.
(2.4) Subsections (2.1) to (2.3) apply to a board, in relation to a school year, after the date under section 76.3 (5) on the report that the board submits to the minister under section 76.3 (10) for that school year.
(5) In this section, “student with an individual education plan” means a student for whom an individual education plan must be designed under the Individual Education Plan Order, Ministerial Order 638/95, but does not include a student who has exceptional gifts or talents.
Organization of classes — consultation at the beginning of the school year
76.2 In each school year, the principal of a school must, within 15 school days after the school opening day set out in the school calendar applicable to the school for the school year,
(a) if applicable, obtain the consent of or consult with the teacher of a class as required by section 76.1 (2.1) (b), (2.2) (b) or (2.3) (b),
(b) consult with the school planning council with respect to the proposed organization of classes within that school for that school year, and
(c) provide the superintendent of schools with a proposed organization of classes for the school for that school year that is, in the opinion of the principal, appropriate for student learning.
B. Brief Grievance Background
i. The First Representative Decision
 The parties agreed to a process whereby certain of the over 1,600 grievances would be resolved as representative grievances. In the First Representative Decision, the arbitrator concluded that 21 of 81 representative classes were in contravention of the Act.
 The arbitrator developed a formula, the Rule of 33, which he applied to assist in determining if the impugned class organizations contravened the Act. He stated that:
480 … I have concluded the formula to determine the disputed classes for which there should be presumptive deference to the principal and superintendent opinions on the organization of the class are those for which on September 30th the sum of the number of students in the class and the number of students in the class with an individual education plan equals or is less than thirty three…
 The result of the application of this formula was that, if the class exceeding the School Act class organization standards did not exceed the Rule of 33, the arbitrator applied a presumption that the principal and superintendent opinions that the classes were appropriate for student learning should be deferred to. He ruled that the employer did not necessarily need to present evidence if the presumption applied. The burden lay on the grievor to rebut the presumption.
 It is also helpful to note the arbitrator’s consideration of just how a principal or superintendent opinion is subject to review, i.e., what is “appropriate for student learning” as stated in ss. 76.1(2.2) and (2.3) and when the Act has been breached despite compliance with the consent or consultation requirements.
 The arbitrator conducted a lengthy analysis relevant to this issue. Beginning at para. 431 of his First Representative Decision, he concluded that the factors which a principal can consider in determining whether class size and composition limits can be exceeded, are not closed. He concluded that “appropriate for student learning” does not focus on teacher workload and stressed that, while consultation enables the consideration of other opinions, the principal and superintendent are the ultimate decision-makers. In discussing the arbitrator’s ability to review, he stated that:
440 At grievance-arbitration, against the background of public review and accountability in the legislative scheme; the legislative history and evolution of the legislated class size and composition provisions; the deliberate choice of the imprecise term “appropriate”; the general principles of deference to the exercise of delegated legislative authority in public administrative systems; and the organizational reality that principals, schools and school districts have processes and systems to respond to emergency and difficult situations, as was seen in the evidence at the representative schools, an arbitrator must be restrained in questioning the merits of the dual principal and superintendent opinions and accord them a broad deference.
441 The factors to be considered by an arbitrator in reviewing a principal's decision to organize a class that exceeds the class size and composition standard and the principal and superintendent opinions the class is appropriate for student learning are factors that relate to transparency, the reason the class was organized as it is and the basis of the opinions the class is appropriate for student learning.
442 Transparency will be fulfilled by meeting the consultation and reporting requirements...
448 The superintendent does not stand in the principal's shoes, does not attend the consultation and cannot be expected to have an opinion about individual classes that approximates the knowledge a principal can be expected to have. In large school districts, highly bureaucratized processes struggle to avoid objectifying children as numbers or categories. However, superintendents do not know, and cannot be expected to know, students' names as teachers and principals do. They cannot be expected to have the level of knowledge of the students and classes the teachers and principals do. They are not required to consult the teacher. Their perspective is necessarily and intended to be broader, but not aloof.
449 The approach to reviewing superintendent opinions is not a rights dispute matrix predicated on future advocacy and litigation. It must be based on an understanding that the requirement for the superintendent opinion is predicated on their organizational leadership accountability within a governance structure. Their role requires them to exercise due diligence that can be executed through structured processes and delegated responsibility. Theirs is a second opinion dependent on the existence and reasonableness of the principal's opinion.
451 If the principal's opinion is reasonably held, the superintendent's opinion cannot undermine the principal's opinion. If the principal's opinion is not reasonable held or is formed without the required consultation, the superintendent's opinion cannot resuscitate the failed process at the school.
 What can be extrapolated from the discussion above is that the arbitrator concluded that he should afford broad deference to the opinions of the principal and superintendent. Put another way, he described the arbitral standard of review of the dual opinions as a deferential one. This conclusion was not challenged by the appellant on appeal. Rather the appellant focuses its challenge on the arbitrator’s assignment of the legal burden.
 Neither party appealed the First Representative Decision. The arbitration process was continued with a further series of representative grievances that were determined in the Second Representative Decision.
ii. The Second Representative Decision
 It is the second decision that the BCTF appeals. In it, the parties continued the grievances filed in respect to the 2006/2007 and 2007/2008 academic years. The BCTF urged the arbitrator to reconsider the imposition of the Rule of 33 on the basis that the rule was an incorrect interpretation of the Act. As noted below, the arbitrator effectively reconsidered his decision but affirmed his view that he had decided this issue correctly in the First Representative Decision. The Second Representative Decision considered 44 grievances. The arbitrator found three of the impugned classes to be in violation of the Act.
 According to the appellant, as of the start of the 2011/2012 school year, about 650 grievances for the 2006/2007 and 2007/2008 academic years remained outstanding and no grieved classes for the following three school years had been arbitrated. The parties hoped that the representative sample of grievances that were arbitrated would enable them to settle most of the outstanding grievances on a principled basis. It was the agreement to try the use of representative grievances for guidance that seems to have opened the way for the arbitrator to create his Rule of 33. While the use of the rule may enhance the efficiency of dealing with the unwieldy volume of grievances, for the reasons stated below, it is my view that the formula was an impermissible modification of the statutory scheme.
 At the second arbitration, the BCTF urged the arbitrator to reconsider the Rule of 33. In reference to the union’s argument, the arbitrator said the following:
101 Consequently, the union submits there is a need to revisit the presumptive deference approach to reviewing the opinions of principals. It submits frustration expressed by local union leaders and teachers as reflected in the recent expedited arbitration decisions is a result of the employer adopting an inflexible approach to the sum of 33 formula on which presumptive deference is based. The union submits “the creation of the rule of 33 is inconsistent with the School Act and has frustrated the dispute resolution process, contrary to the principles of the Labour Relations Code.” Each of the 700 or so classes still in dispute in the 2006-08 school years “must be adjudicated based on an individualized assessment of whether that particular class was appropriate for student learning.” (Outline of BCTF's Submission, March 29, 2011, para 13 - 14)
102 The union submits the previous decisions [the First Representative Decision] were incorrect in their interpretation and approach to the legislation and should not be followed. There is “no legal basis for a formulistic approach to determine whether the opinion about the appropriateness of a specific class is reasonably held.” The union submits there is no basis for giving any deference to the principal's opinion. Creating a presumptive deference for some classes means classes will be found to be organized contrary to the legislation in only the rarest circumstances. It places a “higher than normal obstacle in the prosecution of grievances on the part of the union.” (Outline of BCTF's Submission, March 29, 2011, para 18 - 20)
 The arbitrator continued by quoting from the union’s submissions:
105 The effect of the presumptive deference rule is to create a framework of three tiers of classes:
(a) Those within the [statutory] limits and thus in compliance with the legislation
(b) Those exceeding the [statutory] limits but within the presumptive deference number of 33 which have been prejudged to be in compliance with the class size provisions and appropriate for student learning except in the rarest of circumstances; and
(c) Those exceeding the limits and outside of the presumptive deference number (but even here the burden on the employer is merely a direction that it provide an explanation, not that it satisfy the legal onus)
In our respectful submission, this framework is an impermissible rewriting of the legislation and should not be applied to this second batch of representative classes. (Outline of BCTF's Submission, March 29, 2011, para 27 - 28)
 The arbitrator explained the difficulty in determining under the legislation whether the employer or the grievor carries the burden of proof. This question had practical and important implications for the conduct of a grievance hearing.
 At para. 21 of the Second Representative Decision, the arbitrator cited his analysis in the First Representative Decision regarding whether the teacher of each class must testify. He described the burden of proof issue that arises:
Once it is established there is a class subject to a specific grade class size and composition standard for which there has been a consultation, the more challenging question is who should have the burden of adducing evidence to impeach or justify the principal and superintendent opinions on which the existence of the size and composition of the class depends.
 He concluded the ruling discussed at para. 21 of the Second Representative Decision by making two decisions that are consistent with the First Representative Decision. In respect to classes that did not exceed the Rule of 33 and thus were presumptively organized based on reasonable opinions that the classes were appropriate for student learning, he stated the union must lead evidence to rebut the presumption.
If a class is presumptively appropriate for student learning, the union must adduce evidence to discharge its onus of proof. It will be expected to adduce that evidence from the classroom teacher who disagreed with the principal's opinion [that the class is appropriate for student learning]. If it does not, an inference adverse to the union's grievance could be drawn from the absence or silence of the teacher.
 In respect to classes that did exceed the Rule of 33 and thus were not presumptively appropriate for student learning, the burden was placed on the employer. The teacher could choose not to testify. (The type of burden, whether legal or evidentiary, placed on each of the parties as a result of the Rule of 33, will be discussed later in these reasons.) The arbitrator ruled that:
If a class is not presumptively appropriate for student learning and the union has proven the three elements to establish a sufficiency of evidence to place an obligation of explanation on the employer because the class is not given deference, then there is no further obligation on the union to call additional evidence through testimony of the classroom teacher or in any other specific manner once the employer has adduced its evidence explaining “the reason it organized the class in excess of the class size and composition standard and why there were dual opinions it is a class appropriate for student learning.” The union can choose to rely on the totality of the evidence to attempt to persuade the arbitrator the class is not appropriate for student learning.
 As was foreshadowed by the excerpts above, the arbitrator ruled against the union that the Rule of 33 is inappropriate. He stated that: a contextual approach was required to resolve the matters at hand; the context required consideration of multiple objectives; and the presumptive deference approach was appropriate.
 At para. 118, he cited his reasoning in the First Representative Decision: that the purpose of the School Act provisions in question is to give school districts latitude in class organization and arbitral deference is therefore appropriate for classes presumptively within the range of instructability. The following list of considerations is cited in both of his decisions in defence of the Rule of 33. He stated that presumptive deference:
* recognizes the intended measure of flexibility to organize classes with more than thirty students that is implicit in school district aggregate class size averaging;
* recognizes the legislative expectation that in some situations some classes must have more than three students with an individual education plan;
* allows for differences in schools and school districts operating under a single set of class size and composition standards;
* will provide a high degree of predictability that certain classes with more than thirty students or more than three students with an individual education plan or both will, except in the rarest of situations, not be reorganized by an arbitrator, perhaps requiring expenditures from contingency funds reserved for other purposes;
* will minimize the instances in which teachers will be called to testify despairingly about past or current students and classes and their behaviours and deficits; and
* will facilitate expeditious identification of classes whose organization may be problematic and are to be avoided or organized, supported and approved with care and caution, especially in the future organization of classes.
 In the Second Representative Decision, the arbitrator emphasized that the decision was a continuation of the grievances arbitrated under the First Representative Decision:
121 Consequently, I decline the union's invitation to revisit the interpretations and approaches in the first representative class decision. This decision will approach this second group of representative classes as a continuation intended to apply, extend and refine the principles in the first decision to assist in the resolution of disputes about outstanding classes encompassed by the grievances.
iii. Examples of Application of the Rule of 33
 Although no argument was made in this Court challenging individual grievances, to better understand the implications of the Rule of 33 it is helpful see how the arbitrator applied it in the context of specific grievances dealt with in the Second Representative Decision.
 At para. 450, the arbitrator noted that 9 of the representative classes met the formula for presumptive arbitral deference. One such case was a grade 9 science class. The class had 26 students, 6 of whom had IEPs. Applying the Rule of 33, the class’s sum was 32 and therefore there was presumptive deference that it was reasonable for the administrators to opine that the class was appropriate for student learning. At para. 337, the arbitrator discusses the reasons that the principal concluded the class was appropriate for student learning. He disposed of the grievance, stating that:
462 [The teacher] did not testify about his two Grade 9 Science classes ... The union submits the timetable ruled and the employer failed to explain why the classes were appropriate for student learning and why another Grade 9 Science class had 24 students, none of whom were designated special needs. From the evidence ... the smaller class was the mini-school cohort. Perhaps the school administration could have found ways to balance the 18 designated special needs students among the 5 Science 9 classes, but it chose not to. There is no reason established by the union to question the principal's class organization decisions for these two classes and not defer to the principal's opinions with respect to these classes. [Emphasis added.]
 The next example concerns a class with numbers exceeding the Rule of 33. At para. 406, the arbitrator reviewed a grievance in respect of a grade 9 mathematics class. The class had 31 students, 4 with IEPs, exceeding the Rule of 33. After describing the school environment at the school, he summarized the evidence concerning this particular class:
407 At the September 17th consultation meeting, [the] Department Head ... assigned class had 36 students of whom 5 were designated special needs students. She considered the class to be too large with five designated students. She testified Grade 9 is the most challenging age group to teach and 30 students is a large class for this grade level. She had taught several of the students in Grade 8, but others she did not know. She did not agree with the organization of this class. [The principal] pursued efforts to reduce the class size and was able to move one student when a new elective fine arts course was posted.
408 At September 30th, the class had 31 students of whom 4 were designated special needs students entitled to an individual education plan. Both [the principal and the teacher] knew the classes often began with more than 30 students in September and reduced in size during the year. [The teacher] testified the learning needs of this group were normal. [The principal] had confidence in [the teacher’s] experience and skill as a Mathematics teacher and considered the class to be appropriate for student learning.
 The arbitrator dismissed the grievance, stating:
482 ... The principal’s willingness and efforts to reduce the size of this class was not an acceptance or acknowledgement that the class was not appropriate for student learning. It was an extension of their collegial relationship and a willingness to seek to respond positively to a teacher and department head’s concerns and requests. There is no basis on which the union has established this class was organized contrary to the class size provisions of the School Act. I find the Principal had an informed and reasonably held opinion this class was appropriate for student learning. There is no compelling reason I should not defer to that opinion. The grievance with respect to this class is dismissed. [Emphasis added.]
 In the first grievance discussed above, the union was found to have failed to establish a reason to question the principal’s opinion; the presumption of arbitral deference was not rebutted. In the second grievance, the union failed because the arbitrator made a finding that the principal had an informed and reasonably held opinion that the class was appropriate for student learning and, as a result, the union had not established that the class was organized contrary to the School Act; there was no presumption partially insulating the decision from scrutiny, but the principal had shown that the exception to the general standard applied and therefore deference was due to the employer’s decision.
3. Issues on Appeal
 In its factum, the BCTF alleges that the arbitrator erred in holding that:
Error 1: The Appellant bears the legal burden of establishing that school board organized classes which exceed the Class Size and Composition Limits did not meet the exceptions for exceeding those limits under the School Act.
Error 2: The principal and superintendent’s opinions that a class is appropriate for student learning are presumptively reasonable when that class exceeds the Class Size or Class Composition Limits when the sum of the class size plus the number of students with an IEP is 33 or below in the case of classes for Grades 4 to 12, and 27 or below in the case of classes for Grades 1 to 3.
 The respondent frames its response in the following way:
The Respondent’s position is that the Arbitrator made no errors of law on the legal burden and presumptive deference rulings; that the Arbitrator provided clear criteria and predictable guidelines for application in future disputes as specifically requested and agreed to by the Appellant and Respondent; that the Appellant applied the rulings from the First Representative Decision in subsequent processes and proceedings and did not appeal that Decision; and that the legal burden was not in issue in the decision under appeal so cannot be the basis for a ground of appeal.
A. Jurisdiction and Standard of Review
 The parties agree that this appeal is properly brought pursuant to s. 100 of the Labour Relations Code, 1996 R.S.B.C., c. 244, and that the standard of review on this appeal is correctness (see British Columbia Teachers’ Federation v. British Columbia Public School Employers’ Association, 2011 BCCA 148, 18 B.C.L.R. (5th) 179). I agree with the parties that this 2011 decision is applicable and is binding.
B. Whether the issues have been properly raised on appeal
 As noted above, the respondent argues that this Court should not address the issues raised by the appellant regarding the burdens on the parties and the Rule of 33 because these issues were determined in the First Representative Decision and that decision is not appealed. The appellant says in reply that it never agreed to be bound in respect to all future grievances by the rulings made in respect to the first group of grievances.
 In my view, the proceedings before Arbitrator Dorsey were divided for administrative convenience. As already noted, they were treated by the arbitrator as one continuing grievance. Further, as earlier stated, the arbitrator effectively revisited and confirmed his prior decision on these issues in the Second Representative Decision.
 I do not agree with the respondent that the appellant’s failure to appeal the First Representative Decision is a barrier to the grounds of appeal raised in respect to this appeal.
C. The First Issue: the Rule of 33
 In arguing that the arbitrator erred in creating the Rule of 33, the appellant says he created an arbitrary range within which the principal's opinion that a class is appropriate for student learning is presumptively reasonable, even though that class exceeds the class size or class composition limits as prescribed by the Act. This requires the union to discharge an evidential burden to rebut the presumption.
 The arbitrator’s explanation of his rationale for adopting the Rule of 33 is stated in the First Representative Decision as follows and is cited in the Second Representative Decision:
479 However, the purpose and intention of this legislative scheme, despite using clear words such as “ensure”, “exceed” and “unless”, is to give school districts a latitude in class organization and opinions about class organization appropriate for student learning to which there is to be arbitral deference. It is not absolute deference as submitted by the employer. It is deference to classes presumptively within a range of instructability….
 The appellant says that the arbitrator exceeded his jurisdiction by creating a new category of classes at odds with the Act.
 The respondent argues that the appellant agreed there should be criteria for resolving the disputes and it was this search for clear criteria that resulted in the Rule of 33. As noted by the arbitrator in the First Representative Decision:
12 The agreement on this process was predicated on an intention it would produce some clear criteria for addressing recurring differences on the same issues, establish some predictable guidelines for resolution of many differences and avoid divergent outcomes before different arbitrators. One goal is to fashion some structured approach that provides predictability and efficiency in resolving many, if not most, differences over classes that exceed the legislated class size and composition standard.
 The arbitrator was appointed pursuant to s. 84(3) of the Code. He has no authority respecting the School Act other than to interpret it. While the parties requested him to provide guiding principles, this did not give him the authority to amend the rules created by the statute by enhancing the already considerable leeway given to administrators.
 The respondent says that the Rule of 33 is not an impermissible interpretation of the statutory standard. Rather, it says the arbitrator took the numbers 30 and 3 from the legislation, considered the need for deference to the required dual opinions of principals and superintendents, and developed a formula consistent with the Act. Thus, the respondent argues that there is a valid legislative basis for the arbitrator’s formula for presumptive deference.
 My conclusion is that the legislation creates clear limits; subject to identified exceptions: the board must ensure that class size and composition does not exceed the stated limits unless the exceptions apply. While justification may be increasingly difficult as class size increases or class composition limits are exceeded by larger margins, all classes that exceed the stated limits run afoul of the statutory rules and permit consideration of whether exceeding the limit was appropriate.
 The formulaic distinction drawn by the arbitrator is not supported by the wording of the statutory scheme and may, in some instances, improperly partially insulate decisions concerning classes that exceed the statutory limit but do not exceed the Rule of 33 from review.
 I cannot accede to the respondent’s submission that the Rule of 33 is consistent with the legislation and that it creates a sliding scale of deference depending on the margin by which size and/or composition limits are exceeded. This is not a sliding scale but a categorical rule that is not supported by the wording of the statute. While the rule is expedient, it is not consistent with the statute.
D. Second Issue: the burden of proof
 This second ground of appeal is very much a by-product of the imposition of the Rule of 33 and is thus interrelated with the argument under that heading. There are two sub-issues here: whether the legislation creates an exception and who should bear the legal and/or evidential burden.
i. Whether the Statute Creates an Exception
 The appellant contends that when a class’s size and/or composition exceeds the standard stipulated in the Act, the school board relies on an exception. It submits in its factum:
The legislature selected thresholds for class size and composition under which classes are not subject to review, then created a complex process which involves teacher, principal, parent, superintendent, and board input and accountability, in order to exceed the Limits. A key prerequisite to exceeding the Limits is the formation of the opinion of the principal that a class is appropriate for student learning, a subjective test.
 The appellant also says that the Act requires the school board to establish that the exception applies.
 The appellant notes that, by placing the burden on the grievor to demonstrate that the decision-maker's opinion was not reasonable, the arbitrator has created a situation in which the teacher, or the BCTF on the teacher's behalf, must challenge the subjective opinion of an administrator when the basis of that opinion may be unknown to the teacher.
 The appellant relies on the language of ss. 76.1(2.2) and (2.3). Both are cited above. For convenience, subsection (2.2) provides:
Despite subsection (1) … a board must ensure that the size of any class … does not exceed 30 students unless (a) in the opinions of the superintendent … and the principal…. The … class is appropriate for student learning, [Emphasis added.]
It submits that the use of the word “unless” shows that an exception to the general rule is created.
 The respondent argues that “unless” does not create an exception but is consistent with the legislation’s flexible approach. It submits in its factum that:
The purpose of the legislative scheme “despite using clear words such as ‘ensure’, ‘exceed’ and ‘unless’ is to give schools a latitude in class organization and opinions about class organization appropriate for student learning to which there is to be arbitral deference”. The use of the word “unless” simply refers to the legislative requirements that must be fulfilled before a class is compliant with the legislation. [First Representative Decision, para. 479 …]
 It also submits that the fact that there are absolute limits for the class sizes for younger students shows that the legislature did not intend to create strict limits for the sizes of individual classes for older students. Finally, it submits that the lack of a legislative requirement to provide reasons for exceeding the stated class size and composition standards shows intent to maintain a flexible approach and to give deference to the employer’s decision, which is formed after consultation with teachers.
 Although I agree with the respondent that the scheme is flexible and contemplates a large degree of deference to the opinions of the administrators, I find that the appellant’s interpretation is more consistent with the statutory language. In this case, flexibility and deference are fulfilled through the creation of a relatively easily satisfied exception. Again, the relevant provisions provide that the employer “must ensure” that the standards are met “unless...”. As defined by the Concise Oxford English Dictionary, 11th ed., “unless” means “except when” or “if not”.
 I draw support for my conclusion from the decision of the Supreme Court of Canada in Bell v. Grand Trunk Railway Co. of Canada (1913), 48 S.C.R. 561, 15 D.L.R. 874. In that case, the Court considered s. 275 of the Railway Act which provided, in part, that:
... no train shall pass over any highway crossing at rail level in any thickly peopled portion of any city, town or village, at greater speed than ten miles an hour, unless such crossing is constructed and thereafter maintained and protected in accordance with the orders, regulations and directions specially issued by the Railway Committee of the Privy Council or of the Board in force with respect to such crossing, or unless permission is given by some regulation or order of the Board... [Emphasis added.]
 At 564, Chief Justice Fitzpatrick held that “the words after ‘unless’ are to be read as a proviso creating an exemption from the general prohibition contained in the first part of the section.” At 574, Mr. Justice Anglin held that:
The clause of sub-section 3 introduced by the word “unless” creates an exception or exemption from the duty or obligation of limiting speed imposed generally by the earlier clause of the sub-section. “Unless” is an apt word to introduce an exception. Wilson v. Smith, at page 1556. It “unloosens” what follows it from what precedes it. Manning, Bowman & Co. v. Keenan, at page 57. [Footnotes omitted.]
 Therefore, I am satisfied that an exception is created.
ii. Who bears the burden of proof?
 At the outset, it should be noted that the parties appear to emphasize different elements of the arbitrator’s conclusions relevant to this ground of appeal. The appellant stresses that the statute creates an exception and the legal burden (also referred to as the persuasive burden) should be on the employer to show that the requirements of the statutory exception have been fulfilled. The respondent argues that no exception is created, the presumption is appropriate and affects only the evidential burden, and the legal burden always remains with “he who asserts”, i.e., the union.
 The terms legal burden, persuasive burden and ultimate burden are synonymous. As is elaborated upon below, this is the burden on a party to prove a legal ingredient that is essential to that party’s case. The evidential burden is the term used to denote the burden associated with proof or disproof of a fact. The difference between persuasive burdens and evidential burdens is succinctly addressed in Halsbury’s Laws of Canada as follows:
Persuasive burden of proof. The persuasive burden of proof rests on the party who must establish the facts to the required standard of proof. A party that does not discharge its persuasive burden does not succeed in the action because it fails to prove the facts in issue to the standard required by law.
Evidential burden of proof. The evidential burden of proof rests on the party who must show that there is evidence before the trier of fact that is capable of establishing or disproving a fact in issue. The party who has an evidential burden may either adduce evidence or point to some evidence already adduced that is capable of satisfying the burden. A party that does not discharge its evidential burden with respect to a particular issue will not succeed on that issue because there will be no evidence capable of establishing the facts that the party needs to discharge its persuasive burden, or to prevent the other party from discharging its persuasive burden, on that issue.
Distinguishing the persuasive burden and the evidential burden. An evidential burden “determines whether an issue should be left to the trier of fact”, while a persuasive burden determines the quantum of proof applicable to the issue once it is before the trier of fact. Whether the evidential burden is satisfied is a question of law for the trial judge; whether the persuasive burden is satisfied is a question of fact for the trier of fact. The party bearing the persuasive burden must prove the facts to the required standard. The party bearing the evidential burden does not have to prove any facts to discharge the burden; rather, it must simply satisfy the trial judge that there is evidence on which the trier of fact could decide the issue in the party's favour. By the same token, satisfying the evidential burden is not the same as satisfying the persuasive burden: a party may satisfy the trial judge that the evidence is sufficient to justify leaving a factual issue with the trier of fact, and the trier of fact may then decide that the party has not proved the issue. It is error to conclude that a party has discharged its persuasive burden only because it has discharged its evidential burden.
The party bearing the evidential burden on a particular issue does not necessarily bear the persuasive burden on that issue. For example, in criminal proceedings, the accused bears an evidential burden on many issues concerning defences, but once the accused satisfies the trial judge that there is evidence on which the trier of fact could decide the issue in question in his favour, the issue is normally subject to the usual persuasive burden on the Crown; that is, the Crown must satisfy the trier of fact beyond a reasonable doubt that the issue should be decided against the accused...
(Halsbury’s Laws of Canada - Evidence, 1st ed., “Burden and Quantum of Proof” (Online, LexisNexis Canada Inc.: 2010) at HEV-61.)
 The arbitrator described the effect of the Rule of 33 as a shifting evidential burden or rebuttable presumption. He placed the legal burden and initial evidential burden on the union for classes within the Rule of 33 and the initial evidential burden on the employer for classes exceeding the Rule of 33. In his First Representative Decision, cited at paras. 16, 21 and 118 of his Second Representative Decision, he held that:
487 This union evidence is not a prima facie case that the class is not appropriate for student learning. It is not evidence raising a presumption that must be rebutted, but it is sufficient evidence to place an obligation on the employer to adduce evidence to explain the reason it organized the class in excess of the class size and composition standard and why there were dual opinions it is a class appropriate for student learning.
488 This is an evidentiary burden on the employer because the organization of the class is not given deference as being presumptively appropriate for student learning. It is not an onus to prove the class is not in contravention of the School Act. That onus remains with the union to prove there has been a contravention of the School Act and the collective agreement.
 As will be discussed below, once the union establishes the statutory pre-requisites to the filing of a grievance, namely that the limits are exceeded and consultation has occurred, the proper allocation of the legal burden is on the employer to prove that the opinions were reasonable. This is a legal burden because failure to do so is fatal to the employer’s success.
 The authorities show that there are no steadfast rules regarding the placement of legal or evidential burdens. In Wigmore on Evidence, 3rd ed., vol 9 (Boston: Little, Brown and Company, 1940) at §2486, the following is stated regarding the assignment of legal burdens:
It is often said that the burden is upon the party having in form the affirmative allegation. But this is not an invariable test, nor even always a significant circumstance; the burden is often on one who has a negative assertion to prove; a common instance is that of a promisee alleging non-performance of a contract.
It is sometimes said that it is upon the party to whose case the fact is essential. This is correct enough, but it merely advances the inquiry one step; we must then ask whether there is any general principle which determines to what party’s case a fact is essential.
Still another consideration has often been advanced as a special test for solving a limited class of cases, i.e. the burden of proving a fact is said to be put on the party who presumably has peculiar means of knowledge enabling him to prove its falsity if it is false. This principle has received frequent application in modern statutes making it an offence to pursue a certain occupation without a State license or forbidding a certain act unless in personal circumstances justifying an exception.
But this consideration furnishes no universal working rule; if it did, then the plaintiff in an action for defamation charging him to be living in adultery should be required to prove that he was lawfully married. This consideration, after all, merely takes its place among other considerations of fairness and experience as a most important one to be kept in mind in apportioning the burden of proof in a specific case.
The truth is that there is not and cannot be any one general solvent for all cases. It is merely a question of policy and fairness based on experience in the different situations …
[Footnotes omitted; emphasis added.]
 Wigmore concludes this section by stating that:
There is, then, no one principle, or set of harmonious principles, which afford a sure and universal test for the solution of a given class of cases. The logic of the situation does not demand such a test; it would be useless to attempt to discover or to invent one; and the state of the law does not justify us in saying that it has accepted any. There are merely specific rules for specific classes of cases, resting for their ultimate basis upon broad reasons of experience and fairness.
 In regards to the evidential burden, Wigmore states at §2488:
... For the other burden (the duty of going forward with evidence to satisfy the judge) there is always, at the outset, such a duty for the party having the first burden, or the risk of non-persuasion, until by some rule of law (either by a specific ruling of the judge upon the particular evidence, or the aid of an appropriate presumption, or by matter judicially noticed) the line is passed...
There is therefore no one test, of any real significance, for determining the incidence of this duty.
 As noted in The Law of Evidence in Canada, 3rd ed. (Canada: LexisNexis Canada Inc., 2009) at 94-97, the incidence of the evidential burden normally coincides with the legal burden but this is not always the case. The commentary regarding exceptions, exemptions, excuses, qualifications and provisos in The Law of Evidence in Canada is also instructive. The authors discuss legal and evidential burdens in different contexts. They state that:
§ 3.82 Leaving aside constitutional considerations, the express statutory cases are not troublesome, but as the House of Lords held:
…a statute can, on its true construction, place a burden of proof on the defendant although it does not do so expressly…a burden that has to be discharged on the balance of probabilities.
In the absence of linguistic signposts such as “except for”, “provided that” and “subject to”, it may be a difficult task to determine whether a statutory provision is an essential ingredient, an excuse or a qualification.
§ 3.83 In the cases of Nimmo v. Alexander Cowan & Sons Ltd. and R. v. Hunt, the House of Lords articulated criteria to determine the incidence of the persuasive or legal burden where the statute is vague. The criteria include the mischief at which the statute was aimed, the substance and effect of the enactment, and the practical considerations affecting the incidence of the burden such as the ease or difficulty that the respective parties would encounter in discharging the burden. The latter criterion implicitly resurrects the importance of “facts particularly within the knowledge of a party” as being a rationale for the exception and proviso rule...
§ 3.84 Perhaps there are no hard rules of construction but, rather, there are general criteria for determining the incidence of the persuasive burden. Consider, for example, the tort and crime of assault. In a civil action, the Supreme Court of Canada held that the defendant has the onus of proof that the assault was justified and reasonable force was used. In parallel criminal proceedings, the accused bears only an evidential burden that he or she acted in self-defence. The basis for this distinction does not lie in a mechanical formula or rule of construction but rather in our traditional notions of justice. As American writers conclude, the incidence of the burden of proof is dependant upon considerations of policy, fairness and probability…
 The text also provides that:
§ 3.91 In civil cases, the persuasive burden is more susceptible to being influenced by policy considerations…
§ 3.96 The case law shows that policy, fairness and probability may influence the incidence of either the evidential burden or the persuasive burden in order to deal with perceived difficulties of proof by a party in criminal and civil proceedings, to achieve efficiencies or to level the playing field.
 I conclude that the arbitrator erred in placing the legal burden on the union to disprove the exception. The employer must show that the opinions that the class was appropriate for student learning were reasonable. If it fails to do so, the class organization violates the School Act.
 Three factors support my conclusion. First, as noted above, the wording of the class size and composition limits is strict; the linguistic sign-posts, “must” and “unless” are evidence of this. Second, while a teacher may know about a class, it is the principal and superintendent who have expertise and knowledge on the school-wide concerns that are relevant to whether a class is appropriate for student learning and who know the basis for the required dual opinions. Third, placing the legal burden on the employer, the decision-maker, will not defeat the statutory intent to create flexibility; the exception remains relatively easily met through evidence that the opinions were reasonable.
 In my view, the language of the statute dictates that the employer should carry the legal burden with respect to the exception. It is not for the union to establish that the class is inappropriate for student learning or that the dual opinions were unreasonable, although it will often have to lead evidence of such facts to succeed in a grievance. Nor do I think this is an unfair burden to impose on the school administrators. After all, it is the administrators whose opinions (given without reasons) are required to exceed the statutory standards. The arbitrator was incorrect in imposing the burden of proving the exception on the union. Thus, the overall burden of proving a breach is on the union, but the burden of proving the exception is on the employer.
 Finally, I turn to the last point raised by the respondent. As I understand its submission, it argues that this Court should dismiss the appeal even if the statutory interpretive principles applied by the arbitrator were wrong because, by agreement, the arbitrations were heard with the respondent calling its evidence first and thus the error, if any, was of no consequence. I cannot agree with this contention. The arbitrator adhered throughout his decision to the principle that it was for the union to prove a violation of the statute and to disprove the exception and the Court must assume that he interpreted the evidence accordingly.
 The parties have, because of the enormous volume and administrative burden associated with these grievances, agreed that grievances decided prior to September 10, 2010, should not be set aside by this Court regardless of the outcome of this appeal. In other words, they request this appeal impact only those grievances applicable and effective for grievances regarding the 2010/2011 school year or subsequent years.
 This appeal is unique due to the representative nature of the arbitration and the large number of grievances, settled and unsettled, that stand to be affected.
 Section 9(1) of the Court of Appeal Act, R.S.B.C. 1996, c. 77, provides that:
9 (1) On an appeal, the court may
(a) make or give any order that could have been made or given by the court or tribunal appealed from,
(b) impose reasonable terms and conditions in an order, and
(c) make or give any additional order that it considers just.
 Given that the parties consent on this issue, I would impose the condition that this Court’s order is only applicable and effective commencing the 2010/2011 school year.
 I would allow the appeal and set aside the award, with effect only from September 10, 2010.
“The Honourable Madam Justice Garson”
“The Honourable Madam Justice Prowse”
“The Honourable Mr. Justice Hinkson”