For the reasons which follow, we find that the trial court did not abuse its discretion in ruling that substantial evidence in the record supported SERB’S determination that a ULP occurred. We reverse the judgment of the court of appeals and reinstate the judgment of the trial court upholding SERB’S order that appellee board of education offer appellant reinstatement and award him back pay.
I
In Lorain City Bd. of Edn. v. State Emp. Relations Bd. (1988), 40 Ohio St.3d 257, 259-261, 533 N.E.2d 264, 266-267, this court explained that different standards of review are to be applied by a common pleas court and by a court of appeals when reviewing an order of SERB in a ULP case. When a common pleas court reviews a SERB order, the court must determine whether the order is supported by substantial evidence in the record. This standard of review for a common pleas court is supplied by R.C. 4117.13(D), which *492provides that “[t]he findings of the board [SERB] as to the facts, if supported by substantial evidence, on the record as a whole, are conclusive.” See Lorain City Bd. of Edn., supra, at 259, 533 N.E.2d at 266.
An appellate court, on the other hand, plays a more limited role than a trial court in reviewing the same SERB order. The role of the appellate court is to determine whether the trial court has abused its discretion. The appellate court must affirm the judgment of the trial court if no abuse of discretion occurred. Id., 40 Ohio St.3d at 260-261, 533 N.E.2d at 267.
The trial court in this case reviewed SERB’S order and determined that substantial evidence in the record supported SERB’S conclusion that the board of education committed a ULP. The court of appeals, in reversing the judgment of the trial court, held that the trial court abused its discretion in ruling as it did. We thus examine the decision of the court of appeals, to determine if that court was correct in holding that the trial court abused its discretion.
A
The court of appeals based its decision that the trial court abused its discretion on the trial court’s failure to remand the cause to SERB upon determining that SERB had ruled improperly that the allegations of the complaint were to be deemed admitted.2 We recognize that the trial court could have remanded the cause to SERB, to allow SERB to consider the facts surrounding the allegations improperly deemed admitted. The initial question we address is whether the trial court abused its discretion in failing to remand the cause to SERB.
The court of appeals held that the trial court had a duty to remand this cause to SERB, and that the failure to remand constituted an abuse of discretion. It appears that the court of appeals believed that when the trial court conducted its own review of the evidence not considered by SERB, the trial court usurped SERB’S role as the finder of fact in ULP cases. However, even though we may agree that the trial court should have remanded the cause to SERB, it must be remembered that a court of appeals must affirm a trial court decision on a SERB order in a ULP case unless the trial court abused its discretion. “An abuse of discretion ‘ “ ‘ * * * implies not merely error of judgment, but perversity of will, passion, prejudice, partiality, or *493moral delinquency.’ ” ’ ” Lorain City Bd. of Edn., supra, 40 Ohio St.3d at 261, 533 N.E.2d at 267, quoting State ex rel. Commercial Lovelace Motor Freight, Inc. v. Lancaster (1986), 22 Ohio St.3d 191, 193, 22 OBR 275, 277, 489 N.E.2d 288, 290.
We cannot agree that the trial court abused its discretion by not remanding this cause to SERB for further findings of fact. A thorough examination of the record in this case reveals that the board of education encouraged the trial court to conduct its own consideration of the evidence not considered by SERB. The board of education requested that the trial court use evidence not considered by SERB to find that the decision to nonrenew appellant was not retaliatory. Specifically, the board of education urged the trial court “to reject SERB’S jaundiced ‘in part’ standard of proof and find that the Board of Education has rebutted Kelley’s prima facie case of discrimination and that SERB’S Opinion and Order should be reversed.”
In considering the evidence which SERB had refused to consider, the trial court did as the board of education desired. However, the trial court found circumstantial evidence of discriminatory intent in the record, and upheld SERB’S finding that a ULP had been committed.3 We find it incongruous that the board of education should encourage the trial court to examine the evidence, and then benefit from a ruling by the court of appeals that the trial court abused its discretion when it examined the evidence. We hold that the trial court, in the circumstances of this case, did not abuse its discretion when it did not remand the cause to SERB.
B
Our inquiry does not stop there. We also consider whether the trial court abused its discretion when it found substantial evidence in the record to support the determination that a ULP occurred. It is apparent that the trial court did not abuse its discretion in this regard. The trial court recognized that the good evaluations given to appellant, as well as Principal Grooms’s recommendation that appellant be given a continuing contract, were substantial circumstantial evidence of a discriminatory motive behind the decision to nonrenew appellant. These factors, considered along with appellant’s improvement in setting work schedules and adhering to them (a finding we *494accept as factually established based on our discussion in Part IA of this opinion), clearly constitute substantial evidence to support the determination that a ULP occurred.
II
The trial court in this case, after examining the evidence, determined that the board of education’s decision to nonrenew appellant was motivated both by legitimate and illegitimate reasons. The trial court then applied what was SERB’s approach at that time in “mixed motive” cases, the “in part” test adopted in In re Gallia, supra. Because the employer’s action was motivated at least in part by a desire to retaliate for the participation in a protected activity (filing a grievance), the trial court found that a ULP had occurred, and upheld SERB’s order.
Upon appeal, the appellate court found that the trial court erred in applying the “in part” test, because that test cannot reasonably be reconciled with R.C. Chapter 4117. In ordering this cause remanded to SERB, the court of appeals noted that SERB has announced that it will now apply the so-called “but for” test, which has been applied by the National Labor Relations Board (“NLRB”) since 1980. See In re Ft. Frye Local School Dist. Bd. of Edn. (July 17, 1991), SERB No. 91-005. The court of appeals determined that the “in part” test can lead to absurd results, because a ULP can be found under that test when an employer’s actions are motivated mainly by legitimate reasons, and only in small part by discriminatory ones. Thus, the appellate court found that the “but for” test is mandated by R.C. Chapter 4117.
We do not accept the conclusions drawn by the court of appeals. We therefore examine the “in part” and “but for” causation tests in light of R.C. Chapter 4117. We seek to determine which test, if either, comports with the goals of the General Assembly when it enacted those statutes, particularly R.C. 4117.11 (which defines ULPs) and R.C. 4117.12 (which guides SERB in its disposition of ULP charges).
The motivation behind an employer’s decision to take an action regarding an employee is the central question that must be resolved in a ULP case. R.C. Chapter 4117 makes it SERB’s responsibility to evaluate the factual situation surrounding a ULP charge, and to determine whether a ULP has in fact occurred. Determining the motivation. underlying an employer’s decision almost always presents difficulties which are not easily overcome. Motivation is rarely clear. An employer charged with a ULP will almost always claim that the particular action was taken for sound business reasons, totally unrelated to the employee’s participation in protected activities. The employee will almost always claim that the action was taken to retaliate for his or *495her exercise of protected rights. Since evidence of the employer’s motivation is rarely direct, SERB must rely on a good deal of circumstantial evidence in arriving at its conclusion. To facilitate consideration of ULP cases, administrative agencies {e.g., SERB and the NLRB) utilize causation tests to provide some uniformity in evaluating ULP charges and to give a reviewing court a framework for determining if substantial evidence supports the agency’s decision. The “in part” and “but for” approaches are two examples of such causation tests.
A
R.C. Chapter 4117’s treatment of ULP cases is modeled to a large extent on the federal statutes that empower the NLRB to resolve ULP charges in cases within its jurisdiction. Larson, Ashmus, Bumpass & Ward, Public Sector Collective Bargaining: The Ohio System (1984) 100. Thus, consideration of the NLRB’s experience in applying the “in part” and “but for” tests can be instructive in resolving which test, if either, best accomplishes the goals embodied in Ohio’s statutes regarding ULPs.
Between the 1930s and 1980, the NLRB, when evaluating ULP charges, applied the “in part” test. The NLRB construed the National Labor Relations Act (“NLRA”), Section 151 et seq., Title 29, U.S.Code, to provide that a ULP has occurred when the NLRB finds that an employer’s action was taken at least in part to discriminate against an employee for engaging in protected activities, regardless of other reasons for the action. See, e.g., Consumers’ Research, Inc. (1936), 2 N.L.R.B. 57, 73 (if antiunion animus plays any part in a discharge decision, a violation of the NLRA occurs); Dow Chem. Co. (1939), 13 N.L.R.B. 993, 1023, enforced in relevant part (C.A.6, 1941), 117 F.2d 455 (a violation occurs if the employer acts out of antiunion bias “whether or not the [employer] may have had some other motive in addition to that of repressing [protected activity] and without regard to whether or not the [employer’s] asserted motive was lawful”).
In 1980, in Wright Line, Div. of Wright Line, Inc. (1980), 251 N.L.R.B. 1083, enforced (C.A.1, 1981), 662 F.2d 899, certiorari denied (1982), 455 U.S. 989, 102 S.Ct. 1612, 71 L.Ed.2d 848, the NLRB changed the analysis it applied in resolving ULP cases. In Wright Line, the NLRB adopted a causation test commonly called the “but for” test, in an attempt to alleviate dissatisfaction over the “in part” test expressed by several federal courts of appeals. Id., 251 N.L.R.B. at 1083.4
*496In Wright Line, 251 N.L.R.B. at 1089, the NLRB set forth the following test to evaluate employer motivation in ULP cases: “First, we shall require that the General Counsel [of the NLRB] make a prima facie showing sufficient to support the inference that protected conduct was a ‘motivating factor’ in the employer’s decision. Once this is established, the burden will shift to the employer to demonstrate that the same action would have taken place even in the absence of the protected conduct.”
The Wright Line test allows the employer to present its alleged legitimate reasons for its actions as an affirmative defense. This causation test is commonly called the “but for” test because it establishes that a ULP has occurred when the evidence shows that “but for” the exercise of protected activity, the employer’s action (e.g., a discharge) regarding the employee would not have been taken.
The Wright Line test was not uniformly embraced by the federal courts of appeals. See Comment, Transportation Management: The Validation of Wright Line (1984), 2 Hofstra Labor L.J. 185, 193-194. However, in Natl. Labor Relations Bd. v. Transp. Mgt. Corp. (1983), 462 U.S. 393, 103 S.Ct. 2469, 76 L.Ed.2d 667, the United States Supreme Court held that the NLRB’s Wright Line test was a permissible construction of the NLRA, and was entitled to deference. The court also found that the “in part” test applied before Wright Line “was plainly rational and acceptable.” Transp. Mgt., 462 U.S. at 399, 103 S.Ct. at 2473, 76 L.Ed.2d at 673.
B
As we have said, the ULP provisions of Ohio’s R.C. Chapter 4117 are modeled in many respects upon the NLRA. Since the General Assembly enacted R.C. Chapter 4117 to be effective in 1984, we may safely assume that that body was aware of the controversy in the federal courts concerning the NLRB’s application of the “in part” and “but for” tests, and of Wright Line and Transp. Mgt. Both appellant and the board of education in this case argue that the General Assembly intended to codify a causation test in R.C. Chapter 4117, although they of course disagree as to which test was adopted.
*497A ULP occurs when an employer takes an action regarding an employee that is motivated by antiunion animus. See R.C. 4117.12(A) and 4117.11(A). R.C. 4117.12(B) details the procedure SERB is to follow in taking evidence, and in evaluating that evidence, to determine if a party has engaged in a ULP. R.C. 4117.12(B)(3) requires SERB to decide, based upon the preponderance of the evidence, whether the charged party has engaged in a ULP, and to act on its determination by issuing an order. The order to be issued by SERB is further explained in R.C. 4117.12(B)(4). That statute specifically provides: “No order of the board [SERB] shall require the reinstatement of any individual as an employee who has been suspended or discharged, or require the payment to him of any back pay, if the suspension or discharge was for just cause not related to rights provided in section 4117.03 of the Revised Code * *
Appellant reads R.C. Chapter 4117, and particularly R.C. 4117.12(B)(4), as requiring the “in part” test to determine causation in ULP cases. The board of education urges that R.C. Chapter 4117 mandates the Wright Line “but for” method of analysis. The trial court in this case found that appellant’s interpretation was correct. The court of appeals, in reversing the trial court, held that the “in part” test is not a reasonable interpretation. Furthermore, SERB, in Ft. Frye, supra, has abandoned the “in part” test in favor of the “but for” test. In Ft. Frye, SERB specifically cited the trial court’s opinion in this case, and disagreed with the trial court’s interpretation of R.C. Chapter 4117. Thus, both the court of appeals in this case and-SERB in Ft. Frye have found that the Wright Line approach is the correct test to determine employer motivation in ULP cases.
Initially, we cannot agree with the court of appeals that the “in part” test is not a reasonable interpretation of R.C. Chapter 4117. The “in part” test, because it focuses on the employer’s motivation and requires a finding that a ULP has been committed when it is established that the motivation is improper, obviously comports with R.C. Chapter 4117. Clearly, when a preponderance of the evidence supports a finding that an employer acted at least in part to discriminate against an employee for the exercise of protected rights, SERB’S finding of a ULP is a reasonable interpretation of the statutory directive.
We also do not agree with the court of appeals that R.C. Chapter 4117, and in particular R.C. 4117.12(B)(4), call for the “but for” test. In our view, the Wright Line “but for” method cannot be reconciled with R.C. Chapter 4117. Allowing the employer to present, as an affirmative defense, all the alleged legitimate reasons supporting the action against the employee turns the focus of the inquiry away from the employer’s motivation. The inquiry instead then *498becomes focused on the employee’s work record, and SERB’S factual consideration becomes subsumed by both the employer’s and employee’s evidence on that question. Even though SERB has necessarily already concluded that the employer was motivated by improper reasons before the employer needs to present this evidence, the employer’s improper motivation is sanctioned so long as the employer can convince the factfinder to accept its view of the employee’s work history.5
Contrary to the assertions of the board of education, R.C. 4117.12(B)(4) does not authorize the “but for” test. That statute provides that SERB may not order the reinstatement of any individual “if the suspension or discharge was for just cause not related to rights provided in section 4117.03 of the Revised Code * * *.” We find that this statute, by limiting SERB’S order when the employer’s action was “not related to” protected rights, further emphasizes that a ULP must be found when an employer’s motivation is improper. The “but for” test, because it turns the inquiry away from the employer’s motivation, is not a reasonable interpretation of R.C. Chapter 4117.6
Even though we have found the “but for” approach to be inconsistent with R.C. Chapter 4117, we also find that, unless the employer is given an opportunity to counter the evidence presented by the employee, the “in part” approach will not be the most accurate test. When, for example, it is determined that antiunion animus played a minuscule part in the employer’s decision regarding an employee, a literal application of the “in part” test would appear to mandate a finding that the employer committed a ULP. We find that R.C. Chapter 4117 does not require SERB to conclude that a ULP occurred in that circumstance. The “in part” test must not be applied so narrowly. Rather, the “in part” approach must be broad enough to take into account the actual or true motive of the employer. Thus, only when the employer’s decision regarding the employee was actually motivated by anti-union animus must a ULP be found. In determining actual motivation in the context of the “in part” test, the requirements of R.C. Chapter 4117 are best fulfilled when SERB considers the evidence before it in the framework of a single inquiry, focusing on intent of the employer.
*499Hence, we hold that the “in part” test to determine the motivation of an employer charged with a ULP is mandated by R.C. Chapter 4117. We further hold that under the “in part” test to determine the actual motivation of an employer charged with a ULP, the proponent of the charge has the initial burden of showing that the action by the employer was taken to discriminate against the employee for the exercise of rights protected by R.C. Chapter 4117. Where the proponent meets this burden, a prima facie case is created which raises a presumption of antiunion animus. The employer is then given an opportunity to present evidence that its actions were the result of other conduct by the employee not related to protected activity, to rebut the presumption. SERB then determines, by a preponderance of the evidence, whether a ULP has occurred.
When the “in part” test is properly applied it results in a determination of the actual motive of the employer in taking the action. This approach allows SERB to consider the employee’s work history, but only as circumstantial evidence of the employer’s motivation, and not as a separate inquiry characterized as an affirmative defense. Thus, application of the “in part” test in this manner allows SERB, in resolving ULP charges, to focus on the important inquiry — the motivation of the employer. The problems associated with the “but for” test and its burden-shifting, wrongly focused, bifurcated inquiry are avoided.
We realize that recognizing actual motivation to be a component of the “in part” test will not necessarily make SERB’S task in determining employer motivation an easy one. SERB must still evaluate the evidence presented to determine if antiunion animus actually motivated the employer to take the action against the employee. However, we are confident that this causation analysis will allow SERB to comport more closely with the requirements of R.C. Chapter 4117 in resolving ULP cases.
C
In applying the preceding discussion to the facts of this case, we find that the trial court did not err in applying the “in part” test to determine causation. At the time the trial court rendered its judgment, the “in part” test of In re Gallia was the approach applied by SERB to resolve ULP cases. As explained above, that approach was a reasonable interpretation of R.C. Chapter 4117.
Ill
Conclusion
Based on our discussion in Part I of this opinion, the trial court did not abuse its discretion in finding that appellant’s nonrenewal was motivated by *500antiunion animus. Based on our discussion in Part II of this opinion, we hold that the trial court correctly applied the law to its finding to reach an appropriate conclusion. The judgment of the court of appeals is reversed, and the judgment of the trial court is reinstated.7
Judgment reversed.
A.W. Sweeney, Douglas, F.E. Sweeney and Pfeifer, JJ., concur. Moyer, C.J., and Wright, J., concur in part and concur in judgment.. Because no appeal was taken from the trial court’s determination that SERB erred in ruling that the allegations of the complaint were to be deemed admitted, we must assume that the trial court ruled correctly, and that the allegations of the complaint should not have been deemed admitted.
. It is significant that SERB’S record contained other circumstantial evidence of discriminatory motivation in addition to those factual allegations of the complaint which were deemed admitted. The trial court did not conduct a new consideration of all factual material, only of that which it found SERB should have considered but did not. This was not a situation in which the trial court made factual findings based totally on evidence never considered by SERB.
. The NLRB in Wright Line borrowed the causation test from the decision of the United States Supreme Court in Mt. Healthy City School Dist. Bd. of Edn. v. Doyle (1977), 429 U.S. 274, 97 S.Ct. 568, 50 L.Ed.2d 471S.Ct. 568, 50 L.Ed.2d 471, in which an employee asserted that his *496discharge was motivated by a desire to retaliate against him for his exercise of First Amendment rights. The Supreme Court in ML Healthy held that the plaintiff first had to show that the employer’s dissatisfaction with the plaintiff’s exercise of First Amendment protected activity played some role in the employer’s decision to discharge him. Once that showing was established, the burden then was on the employer to show that the discharge would have occurred even if no motive to punish the plaintiff for his First Amendment activity had been present. Id. at 287, 97 S.Ct. at 576, 50 L.Ed.2d at 484.
. The board of education cites our recent decision in Cleveland Civ. Serv. Comm. v. Ohio Civ. Rights Comm. (1991), 57 Ohio St.3d 62, 565 N.E.2d 579. The board of education argues that that case, which involved application of R.C. Chapter 4112 to a discrimination case, compels application of the “but for” test in the present case. We find that Cleveland Civ. Serv. Comm., because it did not involve R.C. Chapter 4117, is not persuasive.
. We are aware of the need to afford due deference to SERB’S interpretation of R.C. Chapter 4117. See Lorain City Bd. of Edn., supra, paragraph two of the syllabus. However, when SERB’S interpretation cannot be reconciled with the explicit language of R.C. Chapter 4117, that interpretation is not entitled to deference.
. We are cognizant of the broad statement in R.C. 3319.11(G)(7) that “the determination whether to reemploy or not reemploy a teacher is solely a [board of education’s] determination and not a proper subject of judicial review * * We find that the policy of nonreview must yield when interests implicated by R.C. Chapter 4117 are involved. See R.C. 4117.10(A).