International audience It is widely accepted that a person with poor judgment due to mental illness does not bear criminal liability for his acts. However, in this context, the courts are faced with criminals imitating madness in order to escape punishment. It is indeed tempting for the perpetrators of crimes and misdemeanours to cover up their criminal offenses by feigning madness. Therefore the courts try to ferret out potential malingerers in the criminal justice system. When it comes to assessing criminal irresponsibility of the mentally disordered, the intervention of a psychiatrist or psychologist is required before the courts. In fact the knowledge of the experts is instrumental in helping the judge to arrive at the most appropriate sentence. The authenticity of the disorder manifested by the offender is scrutinized in the process. As a matter of fact, both the real and fake patients are liable to undergo a battery of tests to detect malingering. If a defendant pleads insanity at his trial, he must be able to show tangible evidence of mental illness. This situation raises ethical issues. Therefore, in this article, a lawyer teams up with a psychologist in order to study issues related to malingering from a forensic perspective. The first chapter treats the concept of malingering as part of the aforementioned legal framework, thereby identifying the rules that enable a clearer understanding of the concept. The second chapter discusses the methods that allow the experts to detect faked mental illness, relying in particular on documents that Freud wrote as an expert.