She is a professor of psychiatry at Yale and New York University and is the author of Guilty by Reason of Insanity, a book she wrote based on research done in collaboration with neurologist Jonathan Pincus.
During her research Lewis concluded that most, if not all, of the inmates she worked with had been abused as children or had experienced or witnessed potentially traumatic events, including violence.
[4] However, other experts, such as forensic psychologist Barbara R. Kirwin, question Lewis' uses of small samples without control groups, and her own findings indicate a far lower estimate of how many murderers were abused as children.
[5] Lewis in fact focused on several possible antecedents of violence, and summed up her conclusions in 1998: "What brain damage does is it increases emotional lability, impulsiveness, poor judgment.
However, the prosecution took her case apart and it appeared that she had obtained some of her interview material from Shawcross by hypnosis, conducted without proper procedures for protecting against leading questions and false memories.
[10] Lewis has proposed a conspiracy theory to explain why she may have been deliberately undermined, based on the prosecutor sharing the same rare name as a former CIA operative and the possibility that her questioning of Shawcross's army days might have risked revealing he had been put through MKUltra-type brainwashing experiments.
[12] Lewis, along with a New York Times journalist who reported an interview with her prior to Muhammad's capture, has been criticized by the head of the American Psychiatric Association and National Alliance on Mental Illness for having asserted that the man is "clearly psychotic" and probably manic.
Lewis believes that the quest for justice often leads many prosecutors, judges, jurors to overlook things that could be considered mitigating circumstances.
[14] In 2004 Lewis alleged that British playwright Bryony Lavery's hit Broadway play Frozen, particularly the character of 'Agnetha', a psychiatrist sent to evaluate a serial killer, was based on thematic similarities with her book Guilty by Reason of Insanity and verbatim extracts from a New Yorker article about her by Malcolm Gladwell.
However, Gladwell himself has since said he was not comfortable signing over his copyright to Lewis (and did change his mind) and, while understanding that she was upset, suggests that the legal accusations were fueled by a lack of appreciation of the creative arts.