A judge's role in the adoption process is to make any needed changes in the child's legal status. While a waiting child is in foster care, the child's case is usually reviewed periodically in court, to determine whether the goal should be reunification with the birth family or adoption. If the goal is changed, it must be done by a judge. A family court judge will make the decision to terminate parental rights of the birthparents and will preside over the finalization hearing and issue the adoption decree.
The laws of the state in which the child was adopted determine who has access to the original birth certificate or other adoption records, and whether those records are sealed (unavailable). For information about the law in each of the 50 states and the District of Columbia, see the: http://www.childwelfare.gov/adoption/. This links to the Child Welfare Information League’s numerous publications on the legal aspects of adoption.