Kathleen

*442 Opinion

In In re the Marriage of Buol (1985) 39 Cal.3d 751 [ 218 Cal.Rptr. 31 , 705 P.2d 354 ] we held that retroactive application of a statutory provision requiring a writing to prove, upon dissolution of marriage, *443 that property taken in joint tenancy during marriage was actually the separate property of one spouse impaired vested property rights without due process of law. We must now determine whether retroactive application of a companion measure which provides for reimbursement of separate property contributions to community assets absent a signed writing waiving such reimbursement produces the same unconstitutional result. We conclude that it does.

C. James (James) and Kathleen Fabian married on April 27, 1972, and separated on April 29, 1979. A few months after marrying, the couple purchased the Villa Viejo Motel (Villa Viejo), the subject of this dispute, taking title as “C. James Fabian and Kathleen, husband and wife as community property.”

After a contested hearing, the trial court entered an interlocutory judgment of dissolution of marriage on April 23, 1982. In the findings of fact and conclusions of law filed one day earlier the trial court found, inter…