If you’ve ever wondered what happens when a man signs an “acknowledgment of paternity” for a child who later turns out not to be biologically his, Arizona’s highest court just gave a significant answer. In a decision issued September 14, 2026, the Arizona Supreme Court ruled that a biological father can still pursue a paternity case in court , even after another man has already signed an acknowledgment claiming that role.
How We Got Here
In Arizona, unmarried parents have a simple way to establish legal fatherhood: sign an “acknowledgment of paternity.” Once accepted by the state, this document carries the same weight as a court judgment and can only be challenged within a narrow window and on limited grounds. Separately, Arizona law also allows a man who believes he’s the biological father to file his own paternity lawsuit.
The case that reached the Arizona Supreme Court, Strang v. Malay/Hernandez, tested how these two paths interact. A child was born in September 2021, and the mother’s then-partner signed an acknowledgement of paternity that October , both of them genuinely believing he was the biological father. Genetic testing told a different story: results in November 2023, later confirmed in June 2024, pointed to a different man as the biological father.
When that man went to court in 2024 to establish his paternity, the trial court dismissed the case, finding that the existing acknowledgment , and the deadlines for challenging it , barred any new claim. The case made its way to the Arizona Supreme Court.
What the Court Decided
Writing for the majority, Justice Maria Elena Cruz held that the deadlines and finality rules attached to an acknowledgment only bind the people who signed it. They don’t erase a biological father’s separate, legislatively created right to bring his own paternity action , even if he never signed anything himself.
The Court’s reasoning centered on how Arizona’s paternity statutes fit together. An acknowledgment of paternity is one way to establish a legal presumption of fatherhood, but it isn’t the only one, and it doesn’t automatically override every other claim. Once a biological father establishes his own competing presumption of paternity, the trial court has to weigh both presumptions and determine which one should control.
Notably, the Court also flagged a constitutional dimension to its reasoning: reading the statutes to categorically block a biological father from ever asserting his rights would raise serious concerns about his protected interest in building a relationship with his child.
What This Ruling Does, and Doesn’t, Decide
The Supreme Court was careful to keep its holding narrow. This decision does not:
- Invalidate the original acknowledgment of paternity
- Determine who the child’s legal father actually is
- Decide which of the two competing presumptions ultimately wins
Those questions, along with any defenses and consideration of the child’s best interests, now go back to the superior court to sort out. The Supreme Court vacated the earlier dismissal and sent the case back for further proceedings. Vice Chief Justice Lopez and Justices Beene and King dissented from the majority’s decision.
How an Arizona Family Law Attorney Can Help After the Strang v. Malay Decision
This ruling creates new considerations for Arizona families when an acknowledgment of paternity conflicts with a later claim of biological parentage. For acknowledged fathers, biological fathers, and mothers navigating competing paternity claims, the outcome can affect far more than whose name appears on a legal document. Parental rights, child custody, parenting time, and child support may all be impacted by how paternity is ultimately established.
Because these cases can involve competing legal and biological claims, understanding your rights early can be especially important. An experienced Tempe family law attorney at Blake & Pulsifer can help you understand how Arizona’s paternity laws apply to your circumstances and what steps may be available to protect your parental rights and your child’s interests. If you have questions about an acknowledgment of paternity, genetic testing, or a disputed paternity claim, contact Blake & Pulsifer or call 480-838-3000 to schedule a consultation.
