Leah Foster (plaintiff) and David Wolkowitz (defendant) were unmarried when they had M. in Michigan. They signed and filed a Michigan acknowledgment of parentage (AOP) establishing Wolkowitz’s paternity. The next year, the couple moved to Illinois. When the relationship ended a year later, Foster returned to Michigan with the child and filed a paternity action five days later. The next month, Wolkowitz filed a custody suit in Illinois. The Michigan and Illinois judges conferred and decided to hold an evidentiary hearing to determine which state had jurisdiction under the Uniform Child-Custody Jurisdiction and Enforcement Act (UCCJEA). The Michigan court found it had jurisdiction, reasoning that the AOP qualified as an “initial custody determination” under the UCCJEA establishing jurisdiction over any custody, support, or parenting-time disputes, meaning signing the AOP effectively consented to Michigan jurisdiction. Because an AOP grants presumptive initial custody to the child’s mother, the court found that the couple already voluntarily invoked Michigan’s acknowledgement-of-parentage law to designate initial custody, making the UCCJEA provisions inapplicable. The Michigan court subsequently awarded physical custody to Foster, and the appellate court affirmed. Wolkowitz appealed to the Michigan Supreme Court.