# Validity of Wills Written by Dementia Patients Legal experts analyze if a dementia diagnosis automatically invalidates a handwritten inheritance will. - **Source:** [Dong-A Ilbo](https://www.donga.com) - **Published:** 2026-11-05 - **Topic:** [politics](https://brifing.si/c/politics) - **Original article:** - **On Brifing:** https://brifing.si/s/6072d64b-a7f2-478a-b395-344fa6cae2cf ## Dementia Diagnosis and Legal Capacity A dementia diagnosis does not automatically render a will invalid under current legal standards. Lawyer Lee Hyun-ho emphasizes that the critical factor is whether the testator possessed sufficient mental capacity at the exact moment of writing the document. Courts must verify if the individual understood the implications of their final decisions. ## The Role of Formal Requirements For a handwritten will to be legally binding, it must strictly adhere to specific formal requirements mandated by law. This includes the testator writing the entire text, date, address, and name in their own hand, followed by a personal seal or signature. Missing any of these elements invalidates the entire document. ## Background of the Estate Dispute The case involves a self-made businessman who operated a small construction firm and invested in real estate. In 2011, he provided 500 million won in business capital to his son. Following a difficult relationship, he divorced his wife in 2015, resulting in the transfer of a commercial building as property settlement. ## Relationship Dynamics and Inheritance The father maintained a particularly close relationship with his son-in-law, often spending leisure time together, such as fishing trips. This bond contrasted with his strained relationship with other family members. The father eventually decided to leave his entire estate to the son-in-law, triggering a legal battle with his biological daughter. ## Assessing Mental Competence at Writing Legal experts examine medical records and witness testimonies to determine the testator's cognitive state when the will was drafted. If the father was in a lucid interval or retained enough cognitive function to comprehend the nature of his assets and beneficiaries, the will may be upheld despite a prior dementia diagnosis. ## The Burden of Proof In inheritance disputes, the burden of proof lies with those challenging the validity of the will. Family members must provide concrete evidence that the testator lacked the mental capacity to make such decisions at the time of writing. Without clear proof of incapacity, the document remains the primary legal instrument for distribution. ## Impact of Prior Financial Support The father had previously supported his son with 500 million won in 2011, which may influence how courts view the fairness of the final distribution. While the law allows for testamentary freedom, significant prior gifts are often considered during probate proceedings to assess the overall intent and fairness of the estate allocation. ## Legal Precedents and Future Implications This case highlights the complexities of inheritance law when cognitive decline is involved. Families should ensure that estate planning is conducted well before health issues arise to avoid costly litigation. Courts prioritize the testator's intent, provided that the legal formalities are met and mental capacity is verified by objective medical evidence. ## Sources covering this story - https://www.donga.com/news/Society/article/all/20261106/134975937/1 — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._