Plaintiff Gail L. Mackay challenges a trial court’s jury instruction which directed the jury to find in Plaintiff’s favor in a discrimination case brought pursuant to RCW 49.60.180(2), only if it concluded, inter alia, that gender was the "determining factor” in the decision by the Plaintiff’s former employer, Defendants Acorn Custom Cabinetry, Inc. and Robert Anderson, to discharge the Plaintiff.
Plaintiff was employed as a salesperson by Defendant Acorn Custom Cabinetry, Inc., from November 1988 until January 9, 1992, at which time she was involuntarily terminated. At that time, Plaintiff was informed by Defendant Robert Anderson, President of Acorn, that she was being discharged for economic reasons. Shortly after dismissing Plaintiff, however, Anderson rehired a male salesperson who had worked for Acorn before Plaintiff.
In May 1992, Plaintiff filed an action against both Acorn and Anderson pursuant to RCW 49.60.180(2), in which she claimed, inter alia, that she was unlawfully discharged due to her gender. The case proceeded to a jury trial in January 1994.
At trial, Plaintiff alleged that her male counterparts at Acorn were given preferential treatment. Anderson acknowledged that Plaintiff was instructed to turn her accounts over to a male co-worker when business declined and that one of Plaintiff’s male co-workers received a *305company car phone while she did not. Plaintiff also alleged that Acorn is a "gender hostile work environment”. Br. of Appellant, at 7. Anderson testified that photographs of partially clad women are affixed to some of the walls in Acorn’s offices, that derogatory comments are occasionally made about women, and that women are sometimes referred to as "girls”. Verbatim Report of Proceedings (VRP), at 39.
As further proof of discrimination, Plaintiff proffered a recommendation letter given to her by Anderson, in which he wrote: "I have never met another female with as much cabinet knowledge and sales ability as she has”. Clerk’s Papers, at 104; see VRP, at 69. She also proffered Anderson’s admission that he would not rehire her should business improve because he did not believe that "women could sell higher priced cabinets”. Clerk’s Papers, at 104.
At trial, Anderson testified that he terminated Plaintiff not for economic reasons, as he told her in January 1992, but because he believed her attitude and job performance to be poor. Anderson claimed that Plaintiff’s poor attitude was manifested by negative comments about the high cost of the company’s product and by conflicts with co-workers, and that this poor attitude contributed to Plaintiff’s unsatisfactory sales performance.
At the close of the presentation of evidence, Plaintiff proposed to the trial court that the jury be instructed to find in her favor if it concluded that gender was a "substantial factor” in Acorn’s dismissal decision. At the same time, Acorn proposed that the jury be directed to find for Plaintiff only if it concluded that gender was a "determining factor” in the decision. After the trial judge and the attorneys for both parties engaged in an extensive debate over the applicable standard, the trial court opted to give a "determining factor” instruction. VRP, at 244. After receiving this instruction, the jury requested a clarification of the term "determining factor”. Clerk’s Papers, at 135. The court responded by indicating:
In determining whether plaintiff’s gender was a determin*306ing factor in the decision by defendant to terminate plaintiff’s employment, you need not find that her gender was the sole motivating factor. However, it is not enough for you to find that her gender entered into the defendant’s decision. In order for you to find that plaintiff’s gender was a determining factor, you must find that but for her gender, plaintiff would not have been discharged.
Clerk’s Papers, at 135.
After deliberating, the jury returned a verdict in favor of Acorn, which it concluded had not unlawfully discharged Plaintiff. Plaintiff subsequently moved for a new trial on the ground the trial court improperly instructed the jury to apply the "determining factor” standard. The trial court denied the motion. Plaintiff then petitioned this court to review the issue.
RCW 49.60.180(2) provides:
It is an unfair practice for any employer:
(2) To discharge or bar any person from employment because of age, sex, marital status, race, creed, color, national origin, or the presence of any sensory, mental, or physical disability or the use of a trained guide dog or service dog by a disabled person.
At issue in the present case is the meaning of the phrase "because of’ as utilized in this statute. Plaintiff contends that the phrase requires the trier of fact to find for the Plaintiff if it concludes that any of the enumerated attributes was a "substantial factor” in the employer’s adverse employment decision. Acorn urges that the phrase only warrants such a finding if the trier of fact concludes that one of the listed attributes was a "determining factor” in the employer’s decision.
As Acorn notes, the "determining factor” standard has been employed by Washington’s Court of Appeals in a number of cases. See Lords v. Northern Automotive Corp., 75 Wn. App. 589, 881 P.2d 256 (1994); Sellsted v. Washington Mut. Sav. Bank, 69 Wn. App. 852, 851 P.2d 716, review *307denied, 122 Wn.2d 1018 (1993); Burnside v. Simpson Paper Co., 66 Wn. App. 510, 832 P.2d 537 (1992), aff'd, 123 Wn.2d 93, 864 P.2d 937 (1994); Pannell v. Food Servs. of Am., 61 Wn. App. 418, 810 P.2d 952, modified, 815 P.2d 812 (1991), review denied, 118 Wn.2d 1008 (1992); deLisle v. FMC Corp., 57 Wn. App. 79, 786 P.2d 839, review denied, 114 Wn.2d 1026 (1990); Stork v. International Bazaar, Inc., 54 Wn. App. 274, 774 P.2d 22 (1989). However, with the exception of the Lords court, none of these courts was presented with the question of whether the "determining factor” standard or the "substantial factor” standard is applicable in an action brought pursuant to RCW 49.60.180(2). Although the Lords court was confronted with this question, it summarily dismissed the plaintiff’s contention that a "substantial factor” instruction should have been given, without offering any analysis or explanation for doing so. Lords, at 609.
In Pannell, there was controversy over the trial court’s invocation of the term "determining factor”. However, the plaintiff in that case did not argue that the "substantial factor” standard should have supplanted the "determining factor” standard. He conceded that the “determining factor” standard was applicable, and instead argued that the "but for” language utilized by the trial court did not reflect that standard. The appellate court disagreed, holding that both the "determining factor” and "but for” language represent the same standard. Pannell, at 435.
Moreover, although each of the Court of Appeals cases cited by Acorn has invoked the "determining factor” standard, none has offered any reason as to why this standard is appropriate. Therefore, these cases offer neither persuasive authority nor guidance on the question of whether the "determining factor” test or the "substantial factor” test is the appropriate standard in a case brought pursuant to RCW 49.60.180(2).
Acorn also contends that the Court of Appeals opinions in Hatfield v. Columbia Fed. Sav. Bank, 57 Wn. App. 876, 790 P.2d 1258 (1990) and Carle v. McChord Credit Union, *30865 Wn. App. 93, 827 P.2d 1070 (1992) lend support to its proposition that the "determining factor” standard is appropriate. However, in neither of these cases does the court utilize the phrase "determining factor”. Rather, in Hatfield the court asserted:
"The ultimate issue is whether age was a factor in a decision of an employer to terminate [a] . . . claimant and whether the age of claimant made a difference in determining whether he was to be retained or discharged.”
(Italics ours.) Hatfield, at 882 (quoting Ackerman v. Diamond Shamrock Corp. 670 F.2d 66, 70 (6th Cir. 1982)). That court also posed the question in the following terms:
Has [claimant] come forward with evidence sufficient to create an inference that [employer] was motivated by discriminatory intent when it terminated him? . . .
(Italics ours.) Hatfield, at 882. Similarly, in Carle the court stated:
"The plaintiff must prove by a preponderance of the evidence that the reason offered by the employer for plaintiff’s discharge is a pretext and that a discriminatory reason more likely motivated the employer.”. . .
(Footnote omitted. Italics ours.) Carle, at 107.
It is not clear whether the "made a difference” and "motivated” language employed by these two courts implicates the "determining factor” standard. Regardless, like the Sellsted, Burnside, Pannell, deLisle, and Stork courts, neither the Hatfield nor the Carle court discussed whether or not the articulated language was appropriate. Therefore, like those cases, these two cases provide no guidance on the question of whether the "determining factor” standard or the "substantial factor” standard is appropriate in a case brought pursuant to RCW 49.60.180(2).
On two previous occasions this court has had the opportunity to pass upon whether the "determining factor” or the "substantial factor” standard should be applied by a trier of fact when it considers whether or not an *309employer has engaged in discrimination. See Wilmot v. Kaiser Aluminum & Chem. Corp., 118 Wn.2d 46, 821 P.2d 18 (1991); Allison v. Housing Auth., 118 Wn.2d 79, 821 P.2d 34 (1991). In both of those cases, this court held that the "substantial factor” standard is the proper one. Acorn urges that those cases are not controlling because each involved a retaliatory dismissal claim, not a discrimination claim brought under RCW 49.60.180(2). While this distinction arguably prevents those cases from controlling the present case, as Acorn suggests, it does not prevent them from providing this court with guidance as to which of the two standards should be adopted in a case involving a claim brought pursuant to RCW 49.60.180(2).
Common to both the Wilmot and Allison decisions is the conviction that if the "determining factor” standard were adopted in a retaliation case, employers would be permitted to violate the public policy of Washington with impunity. The Wilmot court suggested that it is the public policy of this State to protect employees who assert their statutory rights from retaliatory action by their employers. If the "determining factor” standard were adopted in a retaliation case, in order to prevail the employee would have to prove that his or her employer would not have engaged in the allegedly retaliatory action but for the employee’s assertion of his or her statutory rights. Such a high burden of proof is very difficult for an employee to meet. Therefore, reasoned the court, if the "determining factor” standard were adopted an employee’s protection against retaliation would be unduly circumscribed. The Allison court also refused to adopt the "determining factor” standard in part because it believed that the weighty burden of proof with which the employee would be saddled would severely curtail the protection against retaliation afforded to that employee by the public policy of this State.
Underlying this State’s determination to insulate an employee from retaliation is its resolve to eradicate discrimination. In Allison, this court articulated Washington’s position on discrimination in the following manner:
*310Washington’s Law Against Discrimination contains a sweeping policy statement strongly condemning many forms of discrimination. RCW 49.60.010. It also requires that "this chapter shall be construed liberally for the accomplishment of the purposes thereof.” RCW 49.60.020. . . .
Allison, at 85-86. Washington’s disdain for discrimination would be reduced to mere rhetoric if this court were to require proof that one of the attributes enumerated in RCW 49.60.180(2) was a "determining factor” in the employer’s adverse employment decision. This court will not render its own words, and those of the Legislature, hollow. Accordingly, we decline to adopt the "determining factor” standard in a case involving a discrimination claim brought pursuant to RCW 49.60.180(2). Instead, we hold that in order to prevail on such a claim a plaintiff must prove that an attribute listed in RCW 49.60.180(2) was a "substantial factor” in an employer’s adverse employment decision.
This holding is further bolstered by the reasoning of the Allison court. Another reason given by that court for its refusal to adopt the "determining factor” standard is that a retaliatory discharge case is a multiple causation case.
In . . . multiple causation cases — those in which the conduct of more than one defendant or set of circumstances play a part in bringing about a plaintiff’s injury — the application of the "but for” test is deemed unfair, as a matter of policy and social justice, in reaching a just result. The "substantial factor” test is generally applied in the multiple causation cases. This test states that a defendant is liable for a plaintiff’s injury if the defendant’s conduct was a substantial factor in bringing about the injury even though other causes may have contributed to it. . . .
Allison, at 93-94 (quoting Belton, Causation in Employment Discrimination Law, 34 Wayne L. Rev. 1235, 1248 (1988)). Like a retaliatory discharge action, a discrimination action brought pursuant to RCW 49.60.180(2) is also a multiple causation case. Therefore, it is just as unfair to *311erect the high barrier to recovery implicated by the "determining factor” standard in a suit brought pursuant to RCW 49.60.180(2), as it is to do so in a retaliatory discharge suit. In fact, the Allison court noted:
This reasoning for ameliorating the harshness of a "but for” standard of causation applies equally to situations involving discriminatory or retaliatory discharge, because both legitimate and illegitimate motives often lurk behind those decisions.
(Italics ours.) Allison, at 94.
Moreover, in Kastanis v. Educational Employees Credit Union, 122 Wn.2d 483, 859 P.2d 26, modified, 865 P.2d 507 (1993), this court seems to have implied that the "substantial factor” standard is the proper one in a discrimination case brought under RCW 49.60.180. We noted that
a plaintiff must provide direct evidence that the defendant acted with a discriminatory motive and that the discriminatory motivation was a "significant or substantial factor in an employment decision . . .”.
Kastanis, at 491 (quoting Buckley v. Hospital Corp. of Am., Inc., 758 F.2d 1525, 1530 (11th Cir. 1985)).
When the record discloses an error in an instruction given on behalf of the party in whose favor the verdict was returned, the error is presumed to have been prejudicial, and to furnish ground for reversal, unless it affirmatively appears that it was harmless. . . .
A harmless error is an error which is trivial, or formal, or merely academic, and was not prejudicial to the substantial rights of the party assigning it, and in no way affected the final outcome of the case.
State v. Wanrow, 88 Wn.2d 221, 237, 559 P.2d 548 (1977) (quoting State v. Golladay, 78 Wn.2d 121, 139, 470 P.2d 191 (1970)). Had the trial court in the instant case issued a "substantial factor” jury instruction rather than a "determining factor” instruction, the jury very well might have found in favor of Plaintiff. Therefore, the trial court did not make a harmless error when it instructed the jury *312to find in favor of Plaintiff only if it concluded that one of the attributes enumerated in RCW 49.60.180(2) was a "determining factor” in Acorn’s adverse employment decision. The error is therefore presumptively prejudicial and supplies a ground for reversal. We reverse and remand to the trial court for a new trial.
Smith, Guy, Johnson, and Alexander, JJ., and Utter, J. Pro Tern., concur.