While doing some research, I came across a United States Supreme Court case the Society lost in 1944 on the topic of child labor. The two paragraphs below are from, Odd Gods, New Religions & the Cult Controversy, edited by James R. Lewis, Prometheus Books, New York, 2001, pp. 78-9.
"One of the earliest cases involving children in a religious setting was Prince v. Massachusetts (1944). Ms. Prince, a Jehovah's Witness, was the custodian of her nine-year-old niece. She was convicted of violating state child-labor laws for taking her niece with her to sell religious literature. The United States Supreme Court upheld her conviction. It stated that 'the family itself is not beyond regulation in the public interest, as against a claim of religious liberty. . . . [N]either rights of religion nor rights of parenthood are beyond limitation.'
The state has an interest in protecting juveniles under its traditional role as parens patriae (literally, 'parent of the country,' referring to the state's sovereign role as guardian of persons under legal disability). The state's interest is in restricting any conduct that is harmful to the child. 'The state has a wide range of power for limiting parental freedom and authority in things affecting the child's welfare; . . . this includes, to some extent, matter of conscience and religious conviction.' The court indicated that parents could become martyrs if they wanted to, but they did not have the right to make martyrs of their children and subject them to emotional, psychological, or physical injury. The court left no doubt that if a judge perceives that a religious practice or religious belief may be harmful to a child, the court can and will restrict the religious conduct."