Can a Utah court choose a presumed father over a biological father based on the children's best interest? Guanuna v. Sawatzki Explained

Background and facts

For years, Lindsey Sawatzki maintained parallel relationships with her husband, Jonathan Sawatzki, and Juan Miguel Guanuna, deceiving both men about the existence and nature of her relationships with the other. She gave birth to two sons during her marriage to Jonathan, though Miguel is the biological father of both children. When Jonathan filed for divorce in 2019 and was awarded sole custody, Miguel intervened, obtained genetic testing confirming his paternity, and petitioned to terminate Jonathan’s presumed paternity under Utah’s Uniform Parentage Act. After a custody evaluation and bench trial, the district court adjudicated Jonathan as the children’s legal father, finding it was in the children’s best interest to disregard the genetic testing results under Utah Code section 81-5-608.

Key legal issues

Three issues were presented on appeal. First, whether Miguel waived his argument that Section 608 did not apply because he had already rebutted Jonathan’s presumed paternity. Second, whether the district court abused its discretion in applying the Section 608 best-interest factors—including the length of the presumed father’s parental role, the nature of the parent-child relationship, the children’s ages, and the harm from disestablishing presumed paternity. Third, whether the district court erred in denying Miguel’s posttrial motion for relief based on newly discovered voluntary declaration of paternity (VDP) and denial of paternity (DOP) documents, and in declining to hold a hearing on that motion.

Court’s analysis and holding

The Utah Court of Appeals affirmed on all grounds. On the waived statutory interpretation argument, the court held that plain error review is not ordinarily available in civil cases and that Miguel had failed to adequately brief why it should be extended to this paternity action. The court similarly rejected the ineffective assistance of counsel exception, which does not apply in civil proceedings absent a constitutionally protected interest such as termination of parental rights. On the Section 608 factors, the court found no abuse of discretion, emphasizing that Miguel had not marshaled the evidence supporting the district court’s findings—particularly the undisputed fact that Jonathan had served as the children’s exclusive primary caregiver for over four years and the children were thriving in his care. The court also rejected Miguel’s argument that the district court was required to consider whether equitable estoppel barred Jonathan from denying Miguel’s parentage, explaining that the estoppel provision of Section 608 operates to prevent a presumed father or mother from denying the presumed father’s paternity—not to affirmatively establish a biological father’s rights. As to the posttrial motion, the court upheld the denial of a hearing under Utah Rule of Civil Procedure 7(h) because the issues had been authoritatively decided, and found no abuse of discretion in the court’s conclusion that Miguel had not established fraud under rule 60(b)(3) given his purported awareness of the VDP he allegedly signed.

Practice implications

Practitioners handling parentage disputes should note that Utah courts treat the Section 608 best-interest determination as highly deferential to the trial court—appellants must marshal all evidence supporting the court’s findings and identify a legal defect in that evidence, not merely point to conflicting record evidence. Critically, all statutory interpretation arguments must be raised at or before trial; posttrial motions will not preserve them for appellate review, and neither plain error nor ineffective assistance of counsel exceptions will ordinarily rescue waived arguments in civil paternity cases. Counsel should also be aware that a biological father’s equitable estoppel arguments under Section 608 face significant textual obstacles, as the statute’s estoppel provision is directed at protecting—not displacing—the presumed father’s status.