Disability Convention, Legal Capacity and Domestic Law

Nichoson & Ors v Knaggs & Ors [2009] VSC 64 (27 February 2009) The Victorian Supreme Court adopted a human rights approach to the issue of legal capacity for those who have disabilities.  In accordance with the UN Convention on the Rights of Persons with Disabilities (the 'CRPD'), Vickery J accepted the wide construction given to legal capacity and found that courts must ensure that the rights of people with disabilities are given support that is proportional to their needs and that conflicts of interest and undue influence do not occur.


Betty Dyke left a large estate when she died in 2004.  In her 1985 Will she made small monetary gifts to family and friends and left the bulk of her estate to charities.  Betty Dyke made two further Wills in 1999 and 2001 in which she bequeathed her entire residuary estate to three couples and removed the charities that stood to benefit from her 1985 Will.  A codicil in March 2000 appointed three executors, including one man, whom the Plaintiff submitted Betty Dyke had always strongly disliked.  A further codicil in December 2000 added Betty Dyke's solicitor as an executor.  Betty Dyke suffered two disabilities later in life.  She had acute pain caused by curvature of the spine for which she self-medicated and she later developed dementia as a symptom of Alzheimer's disease.


The Victorian Supreme Court found that Betty Dyke lacked testamentary capacity in respect of the 2001 Will and the December 2000 codicil and that undue influence was exercised on her in relation to the 1999 Will.  In reaching this decision, Vickery J considered international instruments to which Australia is a party and the role of the common law in protecting human rights.

Vickery J found that, whilst the Victorian Charter of Human Rights does not recognise freedom to testamentary disposition, the 'freedom to dispose of property after death in the way a person chooses has been recognised for centuries under the common law.'  Testamentary disposition 'is one of the freedoms that shape our society, and an important human right.'

Importantly, Vickery J considered the effect of the Convention on the Rights of Persons with Disabilities.  Australia has ratified the CRPD but has not incorporated it into domestic law.  Vickery J followed the approach of interpretation established by McHugh J in A v Minister for Immigration and Ethnic Affairs, which held that the Vienna Convention on the Law of Treaties 1969 can be used to interpret treaties that have been ratified but not incorporated.  The proposition that international law may be used to guide the development of the common law was qualified by the fact that it should not be used as a 'backdoor' means of incorporating international treaties.

Vickery J found that art 12 of the CRPD can be applied to testamentary capacity.  Article 12(2) states that 'persons with disabilities enjoy legal capacity on an equal basis with others in all aspects of life.'  Following art 32 of the Vienna Treaty, Vickery J used extrinsic sources to find that legal capacity in the CRPD is construed more widely than it is currently interpreted by Australian common law, to mean 'the capacity to exercise rights and undertake duties in the course of individual conduct.'  However, this construction is subject to the limitations set out in art 12(4) of the CRPD, which requires 'safeguards' for people with disabilities when exercising their legal capacity, so that they are free from 'conflict of interest and undue influence.'  Vickery J interpreted this article to mean that 'some people with disability need support to make decisions in the exercise of their legal rights.'

Vickery J recognised that people with disabilities are vulnerable to undue influence when they receive this support.  Testamentary undue influence is established when the influence 'moves from being benign' to when 'it can no longer be said that in making the testamentary instrument the exercise represents the free, independent and voluntary will of the testator.'  Vickery J established a test to determine whether testamentary undue influence has occurred where the evidence is circumstantial.  The test requires that 'the Court must be satisfied that the circumstances raise a more probable inference in favour of what is alleged than not, after the evidence on the question has been evaluated as a whole.'

An additional safeguard is required, being that the testator must have knowledge and approval of the will.  Vickery J approved the principle in Nock v Austin, that where this is in question the propounders have the burden of removing the suspicion.


Vickery J's construction of legal capacity has significant effects for people with disabilities.  With this interpretation, people with disabilities are viewed as having the same legal rights as others.  Where support is required it must be found to be proportional to their needs, given all the circumstances, and that where it is suspicious it must be established that the testator had knowledge of the contents of the Will.

The decision is available at http://www.austlii.edu.au/au/cases/vic/VICSC/2009/64.html.

Jessica Williamson is a Law Student at La Trobe