Children are a uniquely vulnerable population for medical research because they can be easily exploited. This became apparent when ethicists scrutinized research done by Saul Krugman and colleagues in the 1950s and the Willowbrook State School in New York. Willowbrook was a residential facility for children with a variety of neurocognitive problems. In order to better understand the natural history and etiology of hepatitis, Krugman studied hepatitis transmission in these children. Some of his study designs involved deliberate infection of children with bodily fluids from other children who had active hepatitis. Although these studies were done with parental permission, Beecher argued that they were unacceptable because the risks to the children were too high and the informed consent process lacked details about those risks.