Laws passed over many decades, beginning in the 1830s, by state and federal governments, forbidding the employment of children and young teenagers, except at certain carefully specified jobs. Child labor was regularly condemned in the nineteenth century by reformers and authors (see David Copperfield and Oliver Twist), but many businesses insisted that the Constitution protected their liberty to hire workers of any age. In several cases in the early twentieth century, the Supreme Court agreed, declaring federal child labor laws unconstitutional. Eventually, in the late 1930s, the federal Fair Labor Standards Act was upheld by the Court. This law greatly restricts the employment of children under eighteen in manufacturing jobs.