Can I file a marriage nullification lawsuit?

Hello. This is a divorce specialist attorney at Daeryun Law Firm.

Based on the content of your question, after reviewing the case, it is fully possible to file a marriage nullification lawsuit in your mother's situation.

According to the Civil Act, marriage requires "mutual agreement of marital intent between the parties," and the matter you mentioned constitutes a marriage nullification cause where this requirement is not fulfilled.

For a marriage to be established, both parties must voluntarily and clearly express their intention to marry, that is, to accept each other as spouses.

However, if your mother has been in a state where verbal expression of intent or judgment was impossible for a long time due to ALS, she should be considered to have lacked the very ability to express "marital intent" at the time of marriage registration.

Legally, this corresponds to a case where marriage was not established from the beginning, that is, marriage nullification.

Therefore, as a child and direct lineal descendant, you can file a marriage nullification lawsuit.

Pursuant to Article 817 of the Civil Act and Article 2 of the Family Litigation Act, marriage nullification lawsuits fall under the jurisdiction of the family court, and not only the marriage parties themselves but also their direct lineal ascendants and descendants, relatives within the fourth degree of kinship, and prosecutors can file such lawsuits.

That is, procedures are in place for family members, not the mother herself, to dispute the legal effect on her behalf.

In such a marriage nullification lawsuit, since "absence of marital intent" is the key to prove, you must secure the following materials.

① Mother's diagnosis and neurological opinion (clearly stating inability to communicate and lack of judgment)
② Hospitalization and caregiving records at the time of marriage registration
③ Confirmation of who prepared and submitted the marriage registration form
④ Statements and testimony from people around her
⑤ Circumstances of property transfer after marriage (real estate title transfer, withdrawal of deposits, etc.)

Through such evidence, the court will recognize that your mother was in a state where she could not make normal judgment and express her intent at the time of marriage registration.

A marriage nullification lawsuit applies to "cases where marriage was not established from the beginning," which is different in nature from a marriage cancellation lawsuit.

A marriage cancellation lawsuit is a procedure where, even though the marriage was once established, there were defects such as fraud or coercion in the process — that is, where the motivation for marriage was formed by deception or compulsion — and the marriage is dissolved prospectively by court judgment.

On the other hand, a marriage nullification lawsuit is a procedure that considers the legal marriage to have never existed from the beginning because the essential requirements of marriage were lacking.

To summarize, marriage nullification corresponds to cases where there was no marital intent itself (loss of mental capacity, false reporting, etc.), and marriage cancellation corresponds to cases where there was marital intent but there were significant defects in the process (fraud, coercion, etc.).

In this case, if marriage registration was made while your mother had lost mental capacity due to ALS, this constitutes a marriage nullification cause, and you, as her child, can file a lawsuit.

Also, if the other party knew of your mother's condition and exploited it to receive transfers of property such as real estate or deposits, fraud charges may also be at issue.

Therefore, it is important to swiftly proceed with criminal complaints and property preservation measures (provisional attachment, prohibition of disposition) in parallel with the marriage nullification lawsuit.

Through confirmation of marriage registration nullification, you should restore your mother's legal status while simultaneously implementing preservation measures for unjustly transferred property.

Since such cases require complex evidence including medical records, administrative documents, and testimony, it is desirable to organize evidence from the early stage with a divorce specialist attorney.

I recommend that you promptly receive consultation with a divorce specialist attorney in the early stages of the marriage nullification lawsuit.