Within legal circles, DID has been described as one of the most disputed psychiatric diagnoses and forensic assessments are needed. For defendants whose defense states they have a diagnosis of DID, courts must distinguish between those who genuinely have DID and those who are malingering to avoid responsibility, as shown in the fictional book and film Primal Fear. Expert witnesses are typically used to assess defendants in such cases, although some of the standard assessments like the MMPI-2 were not developed for people with a trauma history and the validity scales may incorrectly suggest malingering. The Multiscale Dissociation Inventory (Briere, 2002) is well suited to assessing malingering and dissociative disorders, unlike the self-report Dissociative Experiences Scale. In DID, evidence about the altered states of consciousness, actions of alter identities and episodes of amnesia may be excluded from a court if they not considered relevant, although different countries and regions have different laws. A diagnosis of DID may be used to claim a defense of not guilty by reason of insanity, but this very rarely succeeds, or of diminished capacity, which may reduce the length of a sentence. DID may also affect competency to stand trial. A not guilty by reason of insanity plea was first used successfully in an American court in 1978, in the State of Ohio v. Milligan case. However, a DID diagnosis is not automatically considered a justification for an insanity verdict, and since Milligan the few cases claiming insanity have largely been unsuccessful.
This model posits that behavior is enhanced by media portrayals of DID.Proponents of the SCM note that the bizarre dissociative symptoms are rarely present before intensive therapy by specialists in the treatment of DID who, through the process of eliciting, conversing with and identifying alters, shape or possibly create the diagnosis. While proponents note that DID is accompanied by genuine suffering and the distressing symptoms, and can be diagnosed reliably using the DSM criteria, they are skeptical of the traumatic etiology suggested by proponents. The characteristics of people diagnosed with DID (hypnotizability, suggestibility, frequent fantasization and mental absorption) contributed to these concerns and those regarding the validity of recovered memories of trauma. Skeptics note that a small subset of doctors are responsible for diagnosing the majority of individuals with DID. Psychologist Nicholas Spanos and others have suggested that in addition to therapy caused cases, DID may be the result of role-playing rather than alternative identities, though others disagree, pointing to a lack of incentive to manufacture or maintain separate identities and point to the claimed histories of abuse.