Insane delusion

Wills, trusts and estates
Part of the common law series
Wills
Legal history of wills Joint wills and mutual wills Will contract Codicil Holographic will Oral will Sections Attestation clause Residuary clause Incorporation by reference Contest Testamentary capacity Undue influence Insane delusion Fraud No-contest clause Property disposition Lapse and anti-lapse Ademption Abatement Satisfaction of legacies Acts of independent significance Elective share Pretermitted heir
Trusts
Express Resulting Constructive Common types Bare Discretionary Accumulation and maintenance Interest in possession Charitable Purpose Incentive Other types Protective Spendthrift Life insurance Remainder Life interest Reversionary interest Testamentary Honorary Asset-protection Special needs Supplemental needs Governing doctrines Pour-over will Cy-près doctrine Hague Convention (conflict law) Application in civil law Dishonest assistance
Estate administration
Intestacy Testator Probate Power of appointment Simultaneous death Slayer rule Laughing heir Advancement Disclaimer of interest Inheritance tax
Related topics
Advance directive (Living will) Blind trust Forced heirship Totten trust
Other common law areas
Contract Tort Property Criminal law Evidence
v t e

Insane delusion is the legal term of art in the common law tradition used to describe a false conception of reality that a testator of a will adheres to against all reason and evidence to the contrary. A will made by a testator suffering from an insane delusion that affects the provisions made in the will may fail in whole or in part. Only the portion of the will caused by the insane delusion fails, including potentially the entire will. Will contests often involve claims that the testator was suffering from an insane delusion.

An insane delusion is distinct from testamentary capacity. A testator might be suffering from an insane delusion but otherwise possess the requisite capacity to make a will. Similarly, an insane delusion is distinct from a mere mistake. If suffering from an insane delusion, a testator is not subject to change his or her mind regarding the delusion if presented with contrary evidence, whereas a mistake is capable of being corrected if the testator is told the truth. Additionally, while an insane delusion may cause portions of a will to fail, most courts will not reform or invalidate a will because of a mistake unless it was the result of fraud.^[1]