Couples with children going through a divorce are often forced to determine child custody arrangements. While many couples agree to custody arrangements outside of the family court system, the rest of the couples must allow a judge to render an opinion after listening to both sides of the case with regards to custody. Child custody involves two primary issues- legal and physical. Legal custody refers to rending legal opinions and decisions, specifically around subject matters such as education, religious and medical care. Physical custody refers to the parent in which the child lives with, and can involve either sole or joint custody between the parents. Custody arrangements can be modified during the child's lifetime, up to the age of majority which is 18 in most states. But, it is not easy to modify an agreement with the family courts.