Child adoption laws allow for a person to permanently assume the role of a child's parent from the child's biological or legal parent, effectively transferring all rights and responsibilities associated with being a parent. This process is usually initiated when the biological or legal parents are unable or unwilling to care for the child. Unlike guardianship or other systems designed for the care of the young, adoption is intended to effect a permanent change in status and as such requires societal recognition, Child adoption law either through legal or religious sanction. Historically, some societies have enacted specific laws governing adoption; where others have tried to achieve adoption through less formal means, notably via contracts that specified inheritance rights and parental responsibilities without an accompanying transfer of filiation. Modern systems of adoption, arising in the 20th century, tend to be governed by comprehensive statutes and regulations.