Not everyone exposed to a severe trauma goes on to develop the full PTSD syndrome.  Studies show that about 25% of individuals exposed to a stressor that meets the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, 4^th Edition) stressor severity criterion for PTSD will develop this disorder. Individuals who have been exposed to prior traumas seem to develop PTSD at higher rates than those who have no prior traumatic exposure. 

The main symptom of PTSD is repeated re-experiencing of the traumatic event by means of nightmares, distressing memories or flashbacks, but other criteria must also be met before a diagnosis of PTSD can be assigned to an individual.

Lawyers who represent plaintiffs diagnosed with PTSD may find that their client has been treated or is in treatment with psychotherapy for PTSD. In their treatment records, psychotherapists may assign a diagnosis, such as PTSD, to a traumatized person but will often fail to demonstrate that their patient meets the full criteria for this disorder.

Psychotherapists typically and appropriately focus more on treatment of mental disorders than on precise and extended diagnostic evaluation. In addition, I rarely see, in treatment records, a consideration of whether a psychotherapy patient might be exaggerating or faking symptoms of PTSD.  It is also quite unusual for a psychotherapist to administer psychological tests, such as the Minnesota Multiphasic Personality Inventory (MMPI-2), or to request that such tests be administered by a professional versed in their use, in order to identify possible malingering.  However, a psychologist conducting a forensic examination of a litigant alleging emotional distress following trauma always maintains a skeptical attitude about a litigant’s symptom description, always considers the possibility of malingering (especially in PTSD cases), draws information about the litigant from a wide database including medical records, psychological tests and interviews and carefully documents any diagnosis assigned to a litigant.