Setting Aside a Will or Trust for Lack of Capacity

Will contests and attacks on trusts often involve the question of whether the testator or settlor had the requisite mental capacity at the time the instrument was executed. In most cases, the analysis of capacity to execute wills and trusts is the same. More stringent tests for capacity may apply to trusts, however, when they are irrevocable or when property is transferred to an independent trustee.


To make a valid will, the testator must be at least 18 years of age and of sound mind. More specifically, a person is not mentally competent to make a will if at the time of making the will he or she either:

  • Does not have sufficient mental capacity to (1) understand the nature of the testamentary act, (2) understand and recollect the nature and situation of his or her property, or (3) remember and understand his or her relations to living descendants, spouse, parents, and others whose interests are affected by the will; or
  • Suffers from a mental disorder with symptoms including delusions or hallucinations that result in his or her devising property in a way that, except for the delusions or hallucinations, he or she would not have done.

A testator’s beliefs may be inaccurate without being delusional. A mere unfounded belief does not justify overturning a will when there is any evidence supporting the belief. To destroy testamentary capacity, a delusion must be one so irrational that no normal person could have it.

To justify setting aside a will, the alleged delusions or hallucinations must cause the testator to devise his or her property in a way that he or she would not have done in their absence. It is not sufficient merely to establish that a testator was the victim of delusions or hallucinations.

Setting aside a Will or Trust

Based on various reasons, there are substantive requirements and evidentiary rules that apply to the grounds most typically alleged to set aside all or part of a will or trust, including lack of capacity , undue influence, fraud , duress or menace , mistake , and limitations on transfers to drafters and others. Many of the elements of causes of action for contesting wills are identical or similar to those for contesting trusts. The statutory and case law rules for establishing lack of mental capacity in a will contest, for example, are for the most part equally applicable to trust contests. Mistake is a notable exception, however, serving as a ground for setting aside a trust but not normally useful in attacking a will.