What Is the Truth Behind DNA Testing in Court Proceedings!?

Rewritten on: March 6, 2025

This article explains the legal procedures and countermeasures available when the other party refuses DNA testing during a paternity acknowledgment mediation. It also covers how paternity can be proven through circumstantial evidence and why legal-grade testing matters.

What Is DNA Testing in Paternity Acknowledgment Mediation? Basic Mechanism and Procedure

A child born to a man and woman who are not married is not legally recognized as having a father unless the man himself acknowledges "this is my child" (known as "voluntary acknowledgment"). This is because such a child falls outside the presumption of legitimacy under civil law as a non-marital child, making the acknowledgment procedure essential to establishing a legal parent-child relationship [ref:1]. If the man refuses voluntary acknowledgment, the mother must petition the family court for acknowledgment mediation in order to seek "compulsory acknowledgment," a determination made by court decision.

Acknowledgment mediation is a procedure that decides an extremely important matter for the child's welfare — namely, who the child's father is. For this reason, it is customary for the court to conduct a DNA test as part of its investigation of the necessary facts before rendering a decision [ref:2]. DNA testing is currently the only method that can establish paternity with over 99.99% accuracy, so it is only natural that the court places great weight on it.

However, even in acknowledgment mediation, it is not uncommon for mediation to fail because, for example, the other party does not attend. In that case, the next step is to proceed to "litigation (a suit for acknowledgment)." Even once the case moves to litigation, DNA testing remains extremely important evidence, but there are real cases in which the other party continues to refuse to appear in court.

The Process from Acknowledgment Mediation to Litigation

Below is a summary of the procedural flow when acknowledgment mediation fails.

1. The mother petitions the family court for "acknowledgment mediation"
2. A mediation committee hears both sides and works toward an agreement
3. The court encourages (or orders) DNA testing
4. If the other party fails to attend mediation or refuses DNA testing, mediation is deemed unsuccessful
5. The mother files a "suit for acknowledgment (compulsory acknowledgment litigation)"
6. During litigation, DNA testing is conducted and/or circumstantial evidence is submitted, and the judge renders a decision

The most important point to note throughout this entire process is whether DNA testing can legally be compelled. Under Japan's current legal system, there is no legal means to directly compel someone to undergo DNA testing [ref:3]. In other words, if the other party refuses, it is in fact impossible to physically collect a DNA sample.

Can Paternity Still Be Recognized Even Without DNA Testing?

If the other party refuses DNA testing and does not appear in the litigation, the case ultimately comes down to the judge's decision. In that situation, the mother must submit circumstantial facts — that is, evidence — necessary to prove the parent-child relationship for the judge to consider.

Circumstantial evidence considered effective specifically includes the following.

• SNS messages or emails exchanged around the time of the pregnancy or birth (content suggesting an awareness of being the father)
• No inconsistency between the blood types of the mother and the man
• The fact that intercourse occurred with the presumed father during the period conception was possible
• Proof that there was no intercourse with anyone else during the same period
• Medical records such as prenatal checkup records and delivery records
• Photographs showing evidence of cohabitation, a residential lease agreement, records of living-expense transfers, and the like

When these pieces of circumstantial evidence are evaluated comprehensively and the judge determines that the probability of paternity is high, acknowledgment can sometimes be granted even without DNA testing.

How Refusing DNA Testing Affects a Court Case

There is another extremely important point to note. While the mother's circumstantial evidence is naturally an important factor in the decision, the man's very act of refusing DNA testing can itself work against him in court. A refusal to undergo DNA testing can give rise to the inference that he is refusing precisely because he recognizes that testing would prove paternity — in other words, that he is, in effect, tacitly acknowledging the parent-child relationship [ref:4].

Indeed, there are multiple actual court rulings in which a refusal to undergo DNA testing was taken into account as part of "the overall import of the pleadings" and, combined with other circumstantial evidence, was used to establish paternity. That said, a refusal of DNA testing alone does not automatically result in acknowledgment being granted — it is considered merely as one factor among many in the overall determination.

Court Standards for Judging Cases Where DNA Testing Is Refused

When a court determines paternity without DNA testing, it comprehensively weighs standards such as the following.

As shown above, there are cases in which paternity is recognized through an accumulation of circumstantial evidence even without the direct evidence of DNA testing. However, such determinations tend to leave both parties with a bitter aftertaste, and for the sake of the child's future, it is preferable to reach a clear resolution through DNA testing.

The Importance of Legal Testing and seeDNA's Approach

There are two types of DNA testing: "private testing" and "legal testing." When testing is to be used for legal proceedings such as acknowledgment mediation or litigation, it must always be conducted as legal testing. In legal testing, samples are collected in the presence of a third party, and a strict chain-of-custody control system is maintained from collection through to the reporting of results, which is what allows the results to be admitted as evidence in court [ref:5].

seeDNA is able to conduct legal testing for all types of kinship testing. Through partnerships with more than 200 legal offices nationwide, we provide trustworthy DNA testing witnessed by attorneys, judicial scriveners, and administrative scriveners. Our DNA testing achieves an accuracy of over 99.99%, delivering reliable results grounded in scientific evidence.

The difference between legal testing and private testing
Sample collection for legal testing

Legal Effects That Arise from Acknowledgment

Once acknowledgment is granted, the child gains the following legal rights, which are extremely important for protecting the child's welfare and rights.

• Right to claim child support: the child can claim child-rearing expenses from the father
• Inheritance rights: upon the father's death, the child gains rights as a statutory heir
• Family register entry: the child is entered in the father's family register
• Right to visitation: with the parent-child relationship legally established, this becomes the basis for visitation rights
• Duty of support: the father's legal duty to support the child is confirmed

As shown above, acknowledgment is a procedure with an extremely significant impact on a child's life, and resolving the matter promptly through scientific, objective proof by DNA testing can be said to bring about the best outcome for all parties involved.

Frequently Asked Questions

Q1. What happens if the other party refuses DNA testing during acknowledgment mediation?

A. If the other party refuses DNA testing during acknowledgment mediation, the mediation fails, and the next step is to file a "suit for acknowledgment (compulsory acknowledgment litigation)." Even in litigation, if the other party refuses DNA testing, the judge will render a decision after comprehensively evaluating circumstantial evidence. The refusal of DNA testing itself may also be considered as a factor working against the refusing party.

Q2. Can paternity be acknowledged without DNA testing?

A. Yes, there are cases where it is. By accumulating circumstantial evidence — such as SNS or email exchanges, the fact of sexual intercourse, consistency of blood types, and proof of no relationship with other men — a judge may in some cases determine paternity. However, since DNA testing can reliably prove paternity with over 99.99% accuracy, resolution through testing is considered the most desirable option.

Q3. Can DNA testing be legally compelled?

A. Under Japan's current legal system, there is no direct means of compelling someone to undergo DNA testing. While the court can order DNA testing, it is not actually possible to physically force the collection of a DNA sample. That said, an attitude of refusing DNA testing without a legitimate reason may work against the refusing party in court.

Q4. What is the difference between legal testing and private testing?

A. Legal testing is conducted with a third party such as an attorney or judicial scrivener present at sample collection, under a strict chain-of-custody control system. It can be submitted to court as evidence. Private testing, on the other hand, is intended for personal confirmation and cannot be used as evidence submitted to court. If you are considering acknowledgment mediation or litigation, be sure to choose legal testing.

Q5. What rights does a child gain when acknowledgment is granted?

A. When acknowledgment is granted, the child gains various legal effects, including the right to claim child support, inheritance rights as the father's statutory heir, entry in the family register, the basis for visitation rights, and a confirmed duty of support from the father. This is an extremely important procedure for protecting the child's welfare and future.

Q6. What kind of system does seeDNA use to conduct its DNA testing?

A. seeDNA partners with more than 200 legal offices nationwide and conducts legal testing witnessed by attorneys, judicial scriveners, and administrative scriveners. Our testing accuracy exceeds 99.99%, providing highly reliable results based on international quality standards.

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