There is no fixed definition for the legal principle known as the best interests of a child when the court is deciding on child custody in a divorce case. However, the best interests are generally regarded as the actions and services that best ensure that a child is well taken care of in a healthy and secure environment. This is determined by considering a wealth of factors based on the child's and parents' circumstances.
New York is one of many states that emphasizes family preference and integrity to prevent a child from being removed from a home. State law stresses the importance of a child being able to learn and develop in a permanent residence and in a customary family life, and states that this environment offers the best chances for the child to thrive and develop. The court is urged to ensure that a child remains with or is returned to a birth parent to facilitate this customary family life.
The law also notes that the parents are entitled to raise their children unless the circumstances would endanger the child's well-being. If when considering the best interests of a child it is determined that a birth parent is unable to provide a customary family life, and when foster care is not a satisfactory option, an alternative is sought. In some cases, the birth parents' rights could be revoked to avoid deleterious effects on the child, which frees the child to be adopted.
New York courts have discretion in determining the best interests in child custody proceedings. This includes the investigation of reported child neglect or abuse and any other matters that the court believes will affect the health and safety of a child. The court does not always have to decide on custody matters. Sometimes the parents agree and simply need the court to approve their parenting plan.
Source: Child Welfare Information Gateway, "Determining the Best Interests of the Child", December 15, 2014