Paternity Test Denied for 17 Year Common Law relationship

In the 2026 ONSC 2583 ruling in AB v CD, the court refused a father’s request to perform DNA paternity tests on his four children, whose ages ranged from nine to over eighteen.

The father asserted that, over the course of the couple’s seventeen-year common-law relationship, he had suspected the mother of sexual relations with other men or involvement in commercial sex. The mother denied these claims, countering that he had repeatedly accused her of infidelity and subjected her to violence and other forms of abuse throughout their time together.

Although he sought genetic testing, the father made clear he would continue to meet his parental obligations—his children having always known him as their father—regardless of the outcome. He explained that his true aim was to “obtain proof that many statements given by the applicant … are false.”

Associate Justice Kamal surveyed authorities from several jurisdictions, emphasizing that orders for DNA testing lie within judicial discretion, demand an evidentiary basis, and must be guided by the children’s best interests.

Justice Kamal observed that the father appeared motivated by a desire to humiliate the mother publicly or cast her in a negative light before the children and the court. The father himself had framed the test as a way “to know his story and his history with the mother,” a purpose the judge found unrelated to the welfare of the children. Moreover, there was no admissible evidence suggesting the children were conceived outside the relationship.

The judge noted that compelling DNA testing would force the children into parental conflict and raise questions about their own paternity, resulting in significant harm. He also found it pointless, since the father insisted that any result would not alter his responsibilities.

Although the incomplete record precluded formal findings of family violence, Justice Kamal determined it would be improper to ignore the mother’s allegations and concluded that the father’s application bore “the appearance of litigation abuse and/or coercive control.”

He therefore dismissed the application and directed that the father must not speak ill of the mother in the children’s presence or suggest that their conception was linked to her alleged sex-work activities.