One of the most important distinctions is that unmarried parents seriously should consider having a court case in Illinois, even if the parties are living together as a family unit. Why? One reason is that it is important for the father of the child to establish properly his paternity of that child. This can be accomplished in Illinois by merely completing the state’s Voluntary Acknowledgment of Paternity form. Many couples complete this form at the hospital when the child is born so the father can be listed on the child’s birth certificate.