Korean Courts on Testamentary Capacity in Dementia Cases

A recurring battleground in inheritance disputes is whether a will or a gift made by the decedent during their lifetime truly reflected their intent at that moment. Family members often clash head-on, with some testifying that the decedent was lucid at the time and others insisting that dementia had already progressed substantially. This article walks through what testamentary capacity and donative capacity actually mean, how the courts read each stage of dementia, and what objective evidence families can prepare in advance.

The validity of a legal act ultimately starts with mental capacity

When an adult enters into a contract, the contract is normally valid. The reason is that the person is presumed to have understood the meaning of the contract and to have been capable of deciding to enter into it. In other words, the law presumes mental capacity at the moment of the act.

Wills and gifts are no different in essence. If the person understood the meaning of the will or the gift and could appreciate the resulting changes in legal rights, the act is valid. If that capacity was weakened, or effectively absent, the validity of the act becomes contestable.

This is one of the most frequently shaken battlegrounds in inheritance cases, because those making wills or gifts are typically elderly and often act while facing physical or cognitive limitations.

Dementia stages and the general arc of testamentary and donative capacity

Dementia is not classified by a single yardstick. Still, using the staging frameworks commonly applied in clinical practice, the general arc looks roughly like this.

Dementia caused by disease-related factors such as cerebral hemorrhage may sometimes improve with treatment, but age-related dementia rarely improves. The typical trajectory is one of gradually weakening capacity over time.

Cognitive screening tools commonly used in clinical practice

Once capacity is contested in court, the most decisive input is usually the evaluation of a neurologist at a major hospital such as a university hospital. Even so, there are a few screening tools that clients and families can familiarize themselves with in advance.

• K-MMSE (Korean Mini-Mental State Examination): out of 30 points. Higher scores indicate a state closer to normal. A score of 15 or below is typically read as severe, and within that range testamentary and donative capacity can become an issue.
• CDR (Clinical Dementia Rating): scored at 0, 0.5, 1, 2, or 3. Lower scores indicate a state closer to normal. A score of 2 or above is typically treated as the severe range.
• GDS (Global Deterioration Scale): graded from 1 to 7. Higher numbers indicate a more severe state. Scores of 1 to 3 reflect early or mild dementia, while a score of 4 or above is typically treated as the severe dementia range.

These tools, however, are screening instruments. Actual capacity assessment is not based on the score alone but on a combination of the patient's daily behavior, clinical observation by medical staff, the medications prescribed, and any comorbidities.

Objective evidence families can prepare in advance

When parents are considering making a will or a gift, there are several pieces of objective evidence that children can help put in place.

• A specialist's pre-act diagnostic certificate: a certificate from a neurologist issued just before the will or gift, confirming that testamentary or donative capacity is intact.
• Notarized will: because the will is made through the testator's own statements before the notary, the procedure carries strong evidentiary value as to mental capacity at that moment.
• Will-substitute trust: because the settlor's intent is confirmed and documented in stages during trust design, this structure reduces the room for post-death disputes.
• Video recording: a video of the testator's statements at the moment of drafting the will or agreeing to the gift can serve as objective evidence.

Testamentary capacity and donative capacity differ in the timing of dispute

Both capacities are evaluated under essentially the same yardstick, but the moment at which a dispute crystallizes differs.

• Donative capacity: disputes can begin while the donor is still alive. The donor can directly express intent or rely on contemporaneous test results.
• Testamentary capacity: disputes typically crystallize after the testator's death. Because the testator can no longer be heard, objective evidence from the relevant moment becomes absolutely critical.

Wills made by someone with dementia are frequently the subject of dispute. The outcome turns on the stage of progression at the time the will was made and on the evaluation evidence available for that moment.

Patterns we see in practice

Two patterns recur in consultations.

The first is a notarized will after an early-stage dementia diagnosis. Parents diagnosed at an early stage, often at the urging of a child, make a notarized will. When a neurologist's diagnostic certificate is preserved alongside the will, the combination provides very strong evidence in any later dispute over testamentary capacity.

The second is a mid-stage gift later attacked as void. A real-estate transfer to one child surfaces after death, and the other children argue that the parent could not have had donative capacity at that point. In such cases, neurology charts, prescription records, daily caregiving notes, and medical records from nearby providers are analyzed together to contest the capacity assessment.

Frequently asked questions

Q. Is a will written by someone with an early-stage dementia diagnosis automatically valid? A. The typical trajectory is that it is treated as valid. Even so, the daily behavior of the testator, screening scores, and medications must all be assessed together, and disputes remain possible case by case. An early-stage diagnosis alone does not produce automatic validity.

Q. Are mid-stage gifts treated as void? A. It depends on the facts. The mid-stage range is precisely where both recognition and denial of capacity are possible, which is why the evaluation evidence is decisive. The court asks whether the person could decide to whom to transfer the property and could appreciate the resulting legal consequences.

Q. Where do we obtain evidence to contest testamentary capacity after death? A. Neurology charts, prescription histories, records from nearby hospitals, inpatient and outpatient records, and daily caregiving notes from nursing facilities are the core materials. Once retained, an attorney initiates the procedures to obtain these records from each medical institution.

How to apply this to your own family

If a parent is elderly and considering a will or a gift, the safer sequence is to check the following points in order.

• What stage is the parent's current cognitive state? Are there test results on file?
• Can the act be structured so that objective evidence is preserved alongside it, for example through a notarized will or a will-substitute trust?
• How far has consent or awareness been clarified among other family members?
• Should the medical evidence from the relevant moment be preserved in advance?

If you would like to map out the will and gift structure within your own family, you can also start a chat consultation now.

Attorney Yoon Jisang / Jonjae Law Firm Family and Inheritance Counsel Team Last reviewed 2026-05-30

This article provides general legal information and does not substitute for legal advice on a specific case. Outcomes vary with the facts, so we recommend a separate consultation for any concrete dispute.