In In re Harber's Estate, 104 Ariz. 79, 449 P.2d 7 (1969), a husband and wife entered into a postnuptial agreement, not incident to or in contemplation of separation or divorce, which provided all property not otherwise described therein was to become the sole property of husband. See 104 Ariz. at 84, 449 P.2d at 12. The supreme court concluded that marital partners may "validly divide their property presently and prospectively by a post-nuptial agreement" but such an agreement must include built-in safeguards to ensure the agreement is "free from any taint of fraud, coercion or undue influence; that the wife acted with full knowledge of the property involved and her rights therein, and that the settlement was fair and equitable." Id. at 88, 449 P.2d at 16. Accordingly, although "all contracts or agreements between husband and wife in Arizona are not presumptively void or fraudulent," our supreme court held that spouses may enter a contract to divide their property outside a divorce or separation, but that when such a postnuptial agreement is attacked by a wife on the grounds that the transaction was fraudulent or coerced, or is inequitable and unfair, the wife may have a judicial determination at that time whether the agreement is invalid as to her, and that it is the husband's burden to prove by clear and convincing evidence that the agreement was not fraudulent or coerced, or that it was not unfair or inequitable. Id.