Mutual Wills in UK Law

A key feature of the concept of mutual wills is the irrevocability of the mutual intentions. The test must always be, 'Suppose that during the lifetime of the surviving testator the intended beneficiary did something which the survivor regarded as unpardonable, would he or she be free not to leave the combined estate to him?' The answer must be that the survivor is so entitled unless the testators agreed otherwise when they executed their wills.

Dennis and Joy executed wills in the same terms save that each left his or her estate to the other. But there was no express agreement not to revoke the wills. The fact that each expected that the other would leave them to him is not sufficient to impress the arrangement with a floating trust, binding in equity. A mutual desire that Gary should inherit could not of itself prevent the survivor from resiling from the arrangement.

The bequest of his entire estate by a husband to his wife absolutely and beneficially with a gift over of whatever was left at her death could not take effect in accordance with its terms. Either the interest taken by the wife would be limited or the gift over would be void as repugnant to the absolute and beneficial nature of the gift. In my view that is what both principle and the authorities require.

It is not necessary in such cases to show that the property was acquired by actual fraud (although the principle would apply equally in such cases). This is sufficient in itself to create the fiduciary obligation and to require the imposition of a constructive trust.

The effect of mutual wills upon the distribution of the estate under a later will which is admitted to probate is a matter for the Chancery Division applying the law of trusts; it is not a matter of probate law and practice. The nature of that litigation is not inquisitorial: it is adversarial and, not infrequently, very adversarial as the two families disunited by death battle for their perceived true inheritance.

It is a legally necessary condition of mutual wills that there is clear and satisfactory evidence of a contract between two testators. However, the argument resting on the alleged insufficiency or uncertainty of the terms of this contract is misconceived. The case for the existence of mutual wills does not involve making a contractual claim for specific performance or other relief.

Both sides are agreed on that, and in the course of the oral argument in this court it repeatedly became apparent that the quality of the relevant assurances may influence the issue of reliance, that reliance and detriment are often intertwined, and that whether there is a distinct need for a 'mutual understanding' may depend on how the other elements are formulated and understood.