(dissenting). Section 895.46(l)(a), STATS., requires a governmental unit, here a school board, to pay attorney fees for an employee who is sued as a result of something the employee did or did not do. There is a qualification, however. The suit must be "because of acts committed while carrying out duties as an officer or employe" and the judge or jury must find that "the defendant was acting within the scope of employment." Id. Therefore, the first question we must ask is: "Why did Cynthia Bomber get sued?" The majority and I answer that question differently. I believe that the trouble began when the school board asked Ms. Bomber to forego a week's earned vacation to attend a workshop on behalf of the school district. The majority focuses on later events. But the statute reads: "proceeded against... because of acts committed while carrying out duties as an . . . employe." (Emphasis added.) I believe that we therefore must inquire as to whether this lawsuit was caused because of acts Ms. Bomber committed while carrying out her duties as a school district principal.
Had Ms. Bomber not been asked to forego two weeks' vacation to attend the two workshops, or had she not agreed to do so, this case would not have arisen. She would not have been told that she could accumu*409late two weeks of unused vacation time to compensate her for the two weeks she spent attending to the school district's business. But she did what she was asked to do, and that, not the dispute as to the accounting for her vacation time, is a cause of this lawsuit.
The question of causation is one of fact. Estate of Cavanaugh v. Andrade, 202 Wis. 2d 290, 306, 550 N.W.2d 103, 110 (1996). But the definition of causation is one of law. Cf. Kallas Millwork Corp. v. Square D Co., 66 Wis. 2d 382, 386, 225 N.W.2d 454, 456 (1975). Questions of causation usually arise in negligence and criminal cases, but there is no reason to depart from Wisconsin's unique view of causation in a case not involving negligence or crime. The Wisconsin test for determining causation is whether the conduct at issue was a substantial factor in producing the plaintiffs harm. Cavanaugh, 202 Wis. 2d at 306, 550 N.W.2d at 110. There may be more than one cause of an injury. Ehlinger v. Sipes, 155 Wis. 2d 1, 13, 454 N.W.2d 754, 758-59 (1990).
The school board views Ms. Bomber's payment of only $315 to satisfy her obligation to it as the cause of its injury and this lawsuit. That view was rejected by the trial court. More importantly, that view fails to consider whether this lawsuit would have occurred had the school district and Ms. Bomber not agreed that she could accumulate vacation time to compensate her for attending two conferences. Ms. Bomber's undisputed affidavit reads: "Mr. Keenan [Ms. Bomber's supervisor] represented to me that if I would attend these workshops within the scope of my employment, that the vacation time for 1992 and 1993 would be accumulated."
In order to arrive at its conclusion, the majority must conclude that the school district's agreement with *410Ms. Bomber was not a substantial factor in causing this lawsuit. "Substantial factor" means that "the defendant's conduct has such an effect in producing the harm as to lead the trier of fact, as a reasonable person, to regard it as a cause, using that word in the popular sense." Ehlinger, 155 Wis. 2d at 12, 454 N.W.2d at 758 (quoting Merco Distrib. Corp. v. Commercial Police Alarm Co., 84 Wis. 2d 455, 458-59, 267 N.W.2d 652, 654 (1978)). Here, the trial court determined that the agreement made by Ms. Bomber and Mr. Keenan modified the contract between Ms. Bomber and the school district. I believe that a reasonable person, here, the trial judge, could conclude that this agreement was a substantial factor in producing this lawsuit. It might not have been the only factor, but it certainly was a factor. It is not reasonable to conclude that this lawsuit would have occurred had the agreement not been made.
The school district does not dispute that attending the workshop was one of Ms. Bomber's duties or contend that doing so was outside the scope of her employment. Thus, this lawsuit arose, at least in part, "because of acts committed while carrying out duties as an ... employe." Section 895.46(l)(a), Stats. That statute does not exempt from its application lawsuits brought by an employee's employer. Accordingly, I would affirm the trial court's decision to award attorney's fees and costs to Ms. Bomber. Because I would affirm that decision, the question posed by Ms. Bomber's cross-appeal arises: Did the trial court err by awarding her only $3,000 of the $5,240 billed to her by her attorney? The trial court found that the additional $2,240 was not necessary because the amount in dispute was small. I conclude that unnecessary attorney's services are not reasonable. Section 895.46(l)(a) *411requires only the payment of reasonable attorney fees. Although it makes little difference in a dissent, I would defer to the trial court's determination as to the necessity of the $2,240 in attorney's fees and affirm that determination.