In most states, both parents have equal rights and joint custody of a child they had during marriage, according to the Legal Information Institute at Cornell University Law School. However, courts sometimes alter those rights and custody arrangements if it is in the best interests of the child to do so.
There are two different types of child custody, according to Nolo. Physical custody is the right of a parent to have a child live with her. Alternatively, legal custody is the right of a parent to make decisions about the child's upbringing, such as choosing a school, practicing a religion or making decisions about medical care. In many cases, parents are awarded joint physical and legal custody of a child.
In some cases, a court awards sole physical or legal custody to one parent if it is in the best interests of the child, states the Legal Information Institute. The court considers a variety of factors regarding the child's best interests, including the wishes of the parents, the wishes of the child, the child's relationship with parents and siblings, and the child's comfort in his current school, home and community. Courts also consider the mental health of all parties involved. If one parent is deemed unfit because of a history of drug or alcohol dependency, or child abuse or neglect, the court awards sole custody to the other parent, explains Nolo.
If one parent is awarded sole custody, the other parent usually retains visitation rights, says the Legal Information Institute. Since most courts try to preserve the non-custodial parent's opportunity to repair a broken relationship with a child, visitation rights are denied only in extreme circumstances, such as when the non-custodial parent has abused the child.
Specific laws regarding child custody vary from state to state, notes the Legal Information Institute.