¶ 45. (concurring in part, dissenting in part). I agree with the majority's decision to impose a constructive trust in favor of Sulzer. I disagree, however, with Part IV of the majority opinion to the extent that it authorizes the imposition of a constructive trust in an amount that includes the investment experience of the retirement accounts up to the date of payment. I would affirm the court of appeals on all issues, including its determination that the constructive trust should include the investment experience of the retirement accounts only until the date of Fred Diedrich's death.
¶ 46. As the majority notes, a constructive trust is an "equitable device created by law to prevent unjust enrichment." Wilharms v. Wilharms, 93 Wis. 2d 671, 678, 287 N.W.2d 779 (1980); majority op., ¶ 20. While *515the equities in this case fully support the imposition of a constructive trust against Mary Diedrich even though she is not at fault, her blamelessness should come into play in the discretionary determination of the extent to which investment experience on the retirement accounts is awarded.
¶ 47. The mutual mistake that precipitates the need to impose a constructive trust in this case justifies an award that includes the investment experience on Sulzer's portion of the retirement accounts up to the date of Fred Diedrich's death; it does not justify forcing Mary Diedrich to disgorge the investment experience on her survivorship interest in her deceased husband's retirement accounts. Mary Diedrich played no role in the mistake which led to the unjust deprivation of Sulzer's portion of the retirement accounts. The dispute here is between two essentially innocent parties, one who was a party to the original mistake and one who was not.
¶ 48. The majority finds it significant that the funds remain in the WRS and Copeland accounts and are therefore traceable. Majority op., ¶¶ 41-42. Mary Diedrich should not be penalized for choosing to leave her survivorship benefits in the retirement accounts. I would conclude, as did the court of appeals, that a constructive trust should be imposed in favor of Sulzer in an amount equal to one-half the value of the retirement accounts as of the date of divorce, plus investment experience up to the date of Fred Diedrich's death. Sulzer is certainly equitably entitled to that amount of investment experience; an amount that encompasses the post-death investment experience is harder to equitably justify under the circumstances here.
¶ 49. The constructive trust equities distinguish this case from Washington v. Washington, 2000 WI 47, *516234 Wis. 2d 689, 611 N.W.2d 261. As the majority notes, Washington was a divorce case in which the husband and wife sought to divide the husband's pension. Majority op., ¶ 39. The dispute over the proper valuation of the pension fund was between the divorcing parties, and the divorce judgment specified that the pension was to be divided equally between the parties. Id. Here, the dispute is no longer between the divorcing parties but between a first and second wife over a deceased husband's retirement accounts; the determination of the appropriate valuation of the constructive trust award turns on what is equitably required under the circumstances, not what is required to effectuate an equal property division in a divorce, as in Washington.
¶ 50. Mary Diedrich is an innocent non-party to the mistake which justifies the imposition of the constructive trust in favor of Sulzer. She has suffered the loss of her husband and a prolonged court battle over a legal mistake she had no part in. I would conclude that Sulzer is equitably entitled to a constructive trust in the amount of one-half the value of the retirement accounts as of the date of divorce, plus investment experience up to the date of Fred Diedrich's death. I dissent from that part of the majority opinion which awards investment experience through the date of payment; in all other respects, I concur.
¶ 51. I am authorized to state that Justice JON E WILCOX joins this concurring and dissenting opinion.