In New Zealand, mutual wills can arise:
(a) by recognition of an institutional constructive trust pursuant to the
equitable doctrine of mutual wills, or
(b) in relation to wills signed on or after 1 November 2007 through a claim by the intended beneficiary on a promise in relation to mutual wills as provided for in s 30 Wills Act 2007.
It is not uncommon for couples to have wills that mirror each other’s. That is, for example, partners or husband and wife leave assets to the survivor of them, and then their children (or respective children in a blended family scenario). However, a mirror will, is not,without more, a mutual will. The difference is that a mutual will cannot be changed (beyond what is agreed), while a mirror will can.
The following passages from Cleary v Cockcroft, set out the difference in a practical construct:
 It is clear that Frank and Chrissy, a few years into their relationship, formed an intention to have mirror wills of the nature they eventually executed in October 2009. It is probable that the enthusiasm and firmness with which Garry and Lesley Quayle encouraged Chrissy and Frank along those lines was an influence. But the manner in which Chrissy and Frank were content to indicate to others for some years that they had followed that lead and in fact executed such wills indicated that they did not view
their attention to their will-making as importantly as others may have.
 Chrissy’s diagnosis with bowel cancer in early-January 2009 may well have been the prompt that encouraged Frank and Chrissy to move towards making wills. But the nine months it still took them to take action does not indicate that Chrissy’s illness brought about a significantly more urgent or focused attention on their willmaking.
 There is no direct evidence of any discussions between the two leading up to the instructions they gave to Mr Cockroft of a commitment to not revoking their wills once executed. As I have found on the balance of probabilities that they did receive advice from Mr Cockroft as to the entitlement they would have to revoke their wills, it is improbable that at some point very soon after that discussion they moved to a mutual commitment of non-revocation which they then failed to communicate to Mr Cockroft.
 All the discussions which they subsequently had as to their intentions were at least as, if not more, consistent with their trusting each other to act on their intentions rather than making a mutual commitment to non-revocation. The discussions they had are of the very nature referred to by Doogue J in McNeish v McArthur as reflecting “an honorary agreement” or “mutual expectation or desire”.
 I add this in relation to the pleading of the plaintiffs’ claim. Their claim will fail because they have not established that Frank and Chrissy expressly and/or impliedly agreed not to revoke their 2009 wills without the knowledge and agreement of the other. In this judgment, I have focused on the evidence adduced rather than on the plaintiffs’ claim as particularised. Ms Foley has responsibly not objected to matters proceeding on that basis. However, it is of some significance that the plaintiffs’ pleaded particulars of the non-revocation agreement are largely consistent with the evidence as it unfolded, falling significantly short of particulars which would meet the
test for mutual wills under Lewis v Cotton. The pleaded particulars state:
(a) by executing identical wills under which the whole of their estate
would be given to the other one absolutely and if the other one did not
survive, then to their children and stepchildren …
(b) by their verbal acknowledgement in the presence of each other and
Rochelle Anne Cleary … that each and both of them had agreed and
intended to leave their estate to the respective children and
 Self-evidently, the one conversation expressly pleaded (that between Frank, Chrissy and Rochelle Cleary) was alleged only to contain the advice that Frank and Chrissy had “agreed and intended to leave their estate to the respective children and step-children”. Such intentions, while they clearly existed and were communicated, do not equate to commitments of non-revocation.
The outcome was that the claim of mutual wills was dismissed with costs following the event.
Also see McNeish v McArthur where the plaintiffs were not able to establish that Mr McArthur’s will was invalid by virtue of being in breach of mutal wills. In that case, which involved a blended family, the Doogue J noted that all parties acted in good faith, but nevertheless this did not disturb the proposition that costs follow the event. Doogue J warned against reliance on a line of authority in the context of probate and the Wills Act that where litigation results from the fault of the will-maker costs for all parties can properly be paid from the estate.
Editor’s note: as a general observation, where mutual wills are intended, it is sensible for each will to confirm this with an express statement regarding the mutuality of the wills. This is particularly important where there is a blended family.
- Cleary v Cockroft  NZHC 1452
- Lewis v Cotton  2 NZLR 21
- McNeish v McArthur  NZHC 3281
- McNeish v McArthur  NZHC 1611 (costs)
- Wills Act 2007
- Shirley v Wairarapa District Health Board  NZSC 63
- Harris v Taylor  NZHC 483
- Squires v Nijse HC Aucklnad CIV-2002-404-1618