In most circumstances, a will is revocable by the testator provided he has the capacity to understand the changes he wants to be made. I say most circumstances because where there is a mutual agreement to dispose of property by a will in a particular manner, courts will hold the parties to that agreement. If one party to the agreement has performed their end of the bargain, equitable principles will be relied upon to prevent the other party from backing out of the agreement. This irrevocability arises when two testators agree to enter into "mutual wills."
What is meant by the term "mutual wills?"
Mutual wills refers to wills that dispose of property belonging to two testators - usually a husband and wife. The husband and wife agree, by their wills, that each will obtain a reciprocal benefit under the other's will and that other specified individuals will receive the property of each of them on the death of the survivor. After the survivor dies, the mutual property is distributed to other persons in accordance with the distribution scheme. The wills must be in the nature of a contract.
Conditions Required For Enforcement
To determine whether the mutual wills are valid and enforceable, courts will consider the following:
- Is it clear that the parties entered into an agreement to establish "mutual wills?"
- Did the parties agree not to revoke or change their wills without the consent of the other person?
- Did the first person die without revoking or changing his or her will?
The Law in Ontario
In Edell v. Sitzer, 2001 CanLII 27989 (ON SC), (2001), 55 O.R. (3d) 198 (S.C.J.), at paras 57 and 58, the court succinctly summarized the law about mutual wills as follows:
The doctrine of mutual wills has traditionally been applied in cases where individuals have made separate wills pursuant to an agreement with respect to their terms. Most commonly, they have agreed that each will obtain a benefit under the other's will and that other specified individuals will receive the property of each of them on the death of the survivor. In some cases of this sort, the benefit obtained by the survivor under the other's will has been a life interest; in other cases, it has taken the form of an outright gift. Where the requirements for the application of the doctrine are satisfied, the survivor will not be permitted to defeat the agreement by revoking his or her will after the death of the other. This result is achieved by the imposition of a constructive trust on the survivor's estate for the benefit of those who were intended to benefit under the agreement.
The most fundamental prerequisite for an application of the doctrine is that there be an agreement between the individuals who made the wills. It has been repeatedly insisted in the cases that: (a) the agreement must satisfy the requirements for a binding contract and not be "just some loose understanding or sense of moral obligation" (Re Good child (Deceased),  1 All E.R. 670 (Ch. D.), at p. 681); it must be proven by clear and satisfactory evidence; and (c) it must include an agreement not to revoke the wills.
When deciding whether or not to create mutual wills, the parties should be very clear about what they want to achieve with the mutual wills. What property is covered by the mutual wills? How is the property given?
Do the parties have the capacity to agree to mutual wills and make an agreement not to revoke?
Is the property given to the survivor absolutely - e.g. can the survivor sell the property or give it away? Are there any conditions or limitations imposed on the survivor?
Is there a life interest? If so, what responsibilities will the survivor have with respect to property of deceased - e.g. any fiduciary duties?
How will the mutual wills treat property that is not jointly owned?