A physician who is accepted as an expert witness on the mental competence of persons appearing before a court, either as parties to the legal action or as witnesses. The law does not always require that the alienist be a psychiatrist.The term is still used in some jurisdictions, but many courts have discarded it. It dates back to an earlier view of mental disorder as a condition severe enough to require special legal provisions such as restraint or guardianship. The word itself derives from a Latin word meaning “other” or “stranger,” and the implication is that the mentally unbalanced person is not himself, that is, he is a stranger or alien to himself. An alienist would therefore be an authority on strange behavior.