There can often be a misunderstanding regarding the difference between mutual Wills and mirror Wills.

It is a basic principle that any party is entitled to revoke a Will that he or she has made at any time and to execute a new Will in different terms. This also applies in the case of mirror Wills but the law is prepared to intervene in the case of mutual Wills.

What is a mirror Will?

Mirror Wills are executed by two people, usually spouses or cohabitees, usually at the same time, in identical terms, which usually provide for the whole of the estate of the first testator to die to pass to the second testator on the basis that on the death of the second testator the whole of the combined estate then passes to agreed beneficiaries.

An issue arises if the second testator receives the estate of the first testator but then changes his or her Will and leaves his or her estate to different beneficiaries.  In that case the principle that the second testator is free to change his or her Will applies and there is nothing that the disappointed beneficiaries can do.

What is a mutual Will?

Mutual Wills however are Wills in which the two testators have made a specific agreement as to their disposal of their property on death and again they execute separate Wills in the same terms (or a joint Will) but where in addition the parties agree that the survivor shall be bound by the arrangement in the form of an agreement by the parties not to revoke their mutual Wills. This agreement is usually written into the mutual Wills themselves. When the first of the two testators dies, without having revoked his or her mutual Will the survivor becomes bound by the arrangement and he or she is no longer at liberty to ignore the original agreement.

The principle that the survivor can execute a new Will still applies but the property which was left under the original mutual Will becomes subject to a constructive trust and the persons originally named as beneficiaries of this property are entitled to receive it irrespective of what the replacement Will says.

The agreement not to revoke can be proved by evidence other than a written agreement and the mutual Will itself but there is a high burden of proof if the agreement not to revoke is not clearly set out in writing.

What happens in the case of re-marriage?

Difficulties concerning mutual Wills often arise in circumstances where the survivor re-marries after the first testator's death and acquires a second family with the issue of them likely to benefit at the expense of his or her first family.

Disappointed beneficiaries who believe that they were mentioned in mutual Wills but have now been wrongly disinherited by subsequent Wills should seek legal advice.

A simple promise by a testator to leave property to another third party under a Will does not provide a cause of action if that Will is subsequently changed but there may be other grounds for bringing a claim if the person to whom the promise was made acted to his or her detriment on the strength of the promise.