Paternity law in the United States addresses the legal establishment of fatherhood, which can affect child support, custody, inheritance, and parental rights. Paternity can be established voluntarily through acknowledgment by both parents or involuntarily through court proceedings involving genetic testing if disputed. Once paternity is legally confirmed, fathers gain rights to custody or visitation and responsibilities like child support. Each state has its own laws regarding the timeframe for establishing paternity, with some states allowing challenges to paternity beyond infancy, particularly if new genetic evidence comes to light. Additionally, laws often consider the best interests of the child when making decisions about paternity, support, and custody arrangements.