As a part of family law, the tender years doctrine or tender years presumption has been in existence since the latter part of the 19th century. According to common law, the doctrine proposes that during the tender years of a child (which is generally regarded as such from the age of four and under), only the mother is allowed custody of the child. The tender years doctrine is often raised in divorce proceedings.
Most states in the United States and Europe have scrapped out this presumption. Some courts in the U.S. have ruled against the doctrine insisting that it goes against the equal protection clause found in the 14th amendment of the United States Constitution (it discriminates based on gender).