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Intoxication or Disassociation: Disaggregating Post Traumatic Stress Disorder (PTSD) and Substance Abuse

Compiled by Alex Hendricks

Legal Question
Are psychiatrists capable of identifying the source of a defendant’s diminished capacity at the time of the alleged offense? Can they differentiate between the influences of alcohol abuse and combat-related PTSD in determining whether a defendant possessed the requisite mens rea to be held culpable for a crime? Are judges and juries capable of vetting competing psychiatric research?

Factual Background: The Epidemiological Studies of PTSD and the Historic Confounding of Alcoholism and Post Traumatic Stress Disorder
In 1980, the American Psychiatric Association (APA) formally recognized PTSD in the third edition of its Diagnostic and Statistical Manual of Mental Disorders (DSM – III). Currently in its fifth edition, the APA promulgated new diagnostic criteria for PTSD in 2013.1

PTSD is commonly associated with combat traumas and is prevalent among veterans of foreign wars. Vietnam veterans in particular are more likely to suffer from PTSD.2 In the 1984 National Vietnam Veterans Readjustment study, 15.2% of male Vietnam veterans and 8.1% of female Vietnam veterans had official diagnoses of PTSD. The estimated lifetime prevalence of PTSD among female Vietnam veterans was 26.9%. The same study concluded that for male Vietnam veterans, the estimated lifetime incidence of PTSD increased to 30.9%. A study by Bruce P. Dohrenwend in 2006 would temper the figures downward to 18.7% of all Vietnam veterans having suffered PTSD; however, even with the reduction, the prevalence of PTSD in Vietnam veterans is nearly double the observable amounts in veterans of the Gulf War and Operation Iraqi Freedom.
PTSD symptoms include: 1) Recurrence, wherein the memories of the traumatic event resurface at any time; 2) Avoidance, wherein the PTSD sufferer avoids situations that might trigger memories of the trauma; 3) Negativity, wherein the PTSD sufferer’s worldview is negatively impacted so that perceptions of one’s life are clouded with depression; and 4) Hyper arousal, wherein the PTSD sufferer has "jittery feelings" and paranoia.

Many Vietnam veterans suffering from PTSD exhibited the aforementioned symptoms, but prior to the recognition of PTSD by the APA, veterans were frequently misdiagnosed as alcoholics or having other disorders.3 In truth, PTSD and alcoholism exist simultaneously in many Vietnam veterans. Sixty to eighty percent of Vietnam veterans, seeking treatment for PTSD had concurrent diagnoses of substance abuse, alcohol abuse, or dependence and the alcoholism rate among Vietnam veterans is sixty percent higher than it was for veterans of World War II or the Korean War.
Although the non-recognition of PTSD substantially contributed to the confounding of the two diseases, the most significant factor in misdiagnosing alcoholism was the comorbidity4 of alcoholism and PTSD that produces the same negative coping systems. The PTSD Research Quarterly reported in the fall of 1996 that alcoholism and PTSD have symptomatic overlap that produces the same coping mechanism of substance abuse to mitigate the intensity of the symptoms. Hyper arousal symptoms of PTSD, including heightened sensitivity and "jittery feelings," are equally consistent with the early stages of withdrawal from regular alcohol consumption. Further, addiction to alcohol and PTSD both taint the sufferer’s worldview in a negative direction. PTSD and substance abusers, without proper treatment, use "avoidant coping systems." Avoidant coping systems are those which mask the symptoms, but do not solve the underlying problems of either traumatic experience or addictive compulsions. Avoidant coping systems that exist in both substance abusers and sufferers of PTSD are the excessive consumption of alcohol and other numbing substances.

Because the symptoms and coping mechanisms of PTSD and substance abuse overlap substantially and often exist in comorbidity, doctors incorrectly diagnosed Vietnam veterans as being exclusively alcoholics and not sufferers of PTSD. Though the medical consequences of this misdiagnosis were dramatic, the accuracy of the diagnosis for either PTSD or substance abuse in Vietnam veterans holds legal ramifications that are the subject of the next section.

Legal Background: Implications of Misdiagnosing on the Availability of Defenses

In the context of criminal liability, diminished capacity is a defense that offers an excuse, rather than a justification, for the actions of the defendant. The defendant admits to the conduct alleged by the prosecution, but argues that she is insufficiently blameworthy to necessitate punishment. The argument is not that the actions committed were not wrongful as in a justification defense, but that the defendant in some way does not warrant punishment or should be given a lesser punishment for her actions because some principle makes her less culpable for the harm she caused.

Diminished capacity defenses fall into two categories: mens rea defenses and “partial responsibility” defenses. The former is relevant to the legal question at issue. Mens rea diminished capacity defenses attempt to establish that the defendant has some abnormality that makes the defendant unable to form the intent that an offense requires for a defendant to be guilty.5 The mens rea diminished capacity defense will either make the defendant guilty of a lesser offense or acquit the defendant entirely because the defendant is incapable of fulfilling the mental element of the offense – an intent requirement established by the legislator necessary to hold the defendant criminally liable.

Courts that accept mens rea diminished capacity defenses have accepted combat-related PTSD as a mens rea defense to insulate PTSD-affected veterans from criminal liability. The premise for a PTSD diminished capacity defense is that certain veterans with PTSD develop a transient dissociative reaction when faced with extreme stress. In other words, when conditions are analogous to the initial traumatizing incident, a veteran with PTSD will enter a fugue state that usually passes without incident, but can occasionally result in criminal behavior. When criminal activity occurs, the argument is that the PTSD suffering veteran will mentally revert to the time of the traumatizing event and will perceive the scenario as if it were that original trauma. This mental reversion directly inhibits the veteran’s ability to both perceive what is going on about him in the present moment with any accuracy and to form intent to act based on perception..6 Accordingly, the veteran who can prove the existence of PTSD and a dissociative state can avail himself or herself of a diminished capacity defense that will negate their culpability and potentially provide an escape from criminal liability.

Where a veteran with a PTSD diagnosis can assert a diminished capacity defense to avoid criminal liability, a veteran with alcoholism cannot argue she is incapable of forming the requisite mens rea of an offense exclusively through her status as an abuser of alcohol and drugs. In terms of legal defenses, alcoholism and the abuse of drugs is deemed a "voluntary intoxication" defense that attempts to assert the same mens rea challenge that is present in the PTSD context; however, unlike the PTSD context, the "voluntary intoxication" defense generally fails in negating the intent requirement of most offenses.

Defendants have asserted challenges to the notion that alcoholism and chronic substance abuse is voluntary intoxication, arguing the necessity of acquiescing to the compulsions of their addiction. The common law maintains that each day the alcoholic makes a decision to indulge his or her physiological compulsions, making the decision to ingest intoxicants voluntary. Defendants, now asserting a voluntary intoxication defense based on their alcoholism, will then argue that even though the defendant voluntarily ingested a known intoxicant, the quantity of intoxicant ingested incapacitated the defendant to the extent that the defendant could not form the intent required to hold the defendant criminally liable. Courts have resoundingly rejected this argument, deeming the voluntary act of impairing one’s mental faculties with intoxicants a morally blameworthy course of conduct that renders the actor culpable for the ensuing harm. Even in circumstances where the effect of the intoxicants had unanticipated or unexpected effects, courts are generally unsympathetic because of the perceived immoral nature of ingesting intoxicants.

Ultimately, voluntary intoxication is a defense that rarely exculpates a defendant from criminal liability because it cannot undermine the mens rea requirement of offenses in the same manner as a diminished capacity defense based on PTSD. Even where the defendant-veteran obtains a medical diagnosis of alcoholism or chronic substance abuse, the court perceives the defendant-veteran as voluntarily partaking in intoxicants and generally rejects any intent-forming argument.

Ultimately, voluntary intoxication is a defense that rarely exculpates a defendant from criminal liability because it cannot undermine the mens rea requirement of offenses in the same manner as a diminished capacity defense based on PTSD. Even where the defendant-veteran obtains a medical diagnosis of alcoholism or chronic substance abuse, the court perceives the defendant-veteran as voluntarily partaking in intoxicants and generally rejects any intent-forming argument.

Effects of the Different Defense on Social Scientists at Trial

Where alcoholism and PTSD exist in comorbidity, or where a veteran with PTSD copes with her symptoms through substance abuse, the role of experts retained by the prosecution and the defense is to persuade the fact finders that defendant-veteran’s inability to form the required mens rea is because of either voluntary ingestion (prosecution) or disassociation resulting from PTSD (defense). Consequently, social science disputes where either PTSD or alcoholism produced the criminal activity take the form of a "war of experts" waged through CV comparison and fact-specific inquiries rather than larger epidemiological studies.

The competency and persuasiveness of a psychiatrist to accurately diagnose a defendant-veteran with PTSD and then to convey at trial that the defendant-veteran was in a dissociative state as a result of PTSD at the time of the alleged offense is integral to determining which defenses a defendant-veteran can employ. Where alcohol is involved in an offense, an effective social scientist for the defense must disaggregate the alcohol abuse from the PTSD and persuade a jury that a dissociative state rather than the voluntary intoxication incapacitated the defendant-veteran. Because it is the defense that puts the mental state at issue, it is the responsibility of the defense to proffer psychiatrists who can make a prima facie (or first instance) showing that the defendant-veteran actually has PTSD.

The prosecution, in rebuttal, will offer its own expert testimony to show that alcohol, rather than any substantial mental deficiency, inhibited the defendant-veteran’s mens rea. Again, this takes the form of a fact-intensive inquiry wherein the prosecution’s psychiatrist will examine the defendant-veteran and attempt to isolate facts that support the argument that the defendant-veteran voluntarily ingested substances that would result in the fugue state that existed during the crime. The psychiatrist for the prosecution usually does not challenge the assertion that the defendant was in a fugue state during the crime; rather, psychiatric experts for the prosecution challenge the assertion that the fugue state stems from an underlying condition of PTSD.

This "war of experts" described above manifested in the following case study:

Case Study: People v. Kapsalis

Factual Background

The complainant, Susie Greenspan, was walking toward her boyfriend's house dressed in all black when she observed Kapsalis leaning against the wall of a building adjacent to a vacant lot. As Greenspan passed him, Kapsalis grabbed her and dragged her into the vacant lot with tall grass. When Greenspan began to scream, Kapsalis covered her mouth and threatened to kill her if she screamed.

Kapsalis threw Greenspan to the ground and pinned her down. Greenspan struggled, and Kapsalis again threatened Greenspan and asked her whether she "wanted it easy or hard." Kapsalis then pulled a knife from his utility belt and put it to Greenspan's neck. Thereafter, Kapsalis sexually assaulted Greenspan, and following the assault Kapsalis looked toward the street and ran away.

Greenspan flagged down a police car driven by Officer Robert Hayes. She told Officer Hayes and his partner about the attack and then got into the officers' car and rode with them a short distance until she saw Kapsalis. Greenspan identified Kapsalis as her attacker, and Officer Hayes placed him under arrest. When Hayes searched Kapsalis, he recovered a knife. Upon being advised of his Miranda rights, Kapsalis told Officer Hayes that he had been drinking prior to his arrest and was "high, but not drunk." Kapsalis denied attacking Greenspan.


At trial, Kapsalis testified that on the night of the attack, he had consumed approximately a case of beer and one-half bottle of whiskey. He could not recall the attack, but did remember having a flashback to his combat experiences during his two years in Vietnam. He recalled being in a high-grass area in a vacant lot where he saw "the enemy," Vietnamese dressed all in black. Kapsalis stated that he believed that he was attacking "the enemy." Kapsalis admitted having a knife that night and remembered threatening complainant, but did not recall any sexual assault. Kapsalis testified that he did not know what he was doing or that his acts were wrong and that this was not the first time he had suffered a flashback to his combat experiences in Vietnam. He admitted, however, that he did not tell anyone about the Vietnam flashback until approximately three weeks after his attack.

Following the assault on Greenspan, Kapsalis was confined to the psychiatric ward of a Veterans' Association hospital for a month, and upon his release, began receiving therapy twice weekly. Kapsalis also stopped drinking alcohol and began attending Alcoholics Anonymous meetings.


Was Thomas Kapsalis, at the time of his assault on Greenspan, in a disassociated state consistent with PTSD or was he merely drunk and still able to form the required intent and appreciate the criminality of his actions?

Social Science Experts

Three psychiatrists testified at Kapsalis’s trial after examining the defendant-veteran in accordance with the facts and assertions included in their reports. Two of the psychiatrists testified at trial about the conclusions of their reports that favored the defendant, while the prosecution’s expert testified to Kapsalis’s sanity.

Dr. Henry Conroe, a forensic psychiatrist who earned his degree from Allegheny University of the Health Science and who had been in practice for 13 years prior to Kapsalis, was the first to testify. Dr. Conroe found that Kapsalis was diagnosed with two different mental health conditions: Chronic Post-Traumatic Stress Disorder and Alcohol Dependence. Although Conroe acknowledged the influence of significant alcohol "impair[ing] his judgment," Conroe concluded that Kapsalis’s assault on Greenspan was consistent with the "solution he learned in Vietnam to deal with a potential enemy 'search and destroy."' Conroe came to this conclusion primarily because of the atmospheric similarities to Kapsalis’s time in Vietnam that existed during the assault (i.e. the black clothing, the tall grass spaces, and the tactics Kapsalis used to pin Greenspan down).8

Dr. Lee Martin followed Dr. Conroe’s testimony by reporting conclusions that were more ambiguous, but still favored the defense’s PTSD argument. Dr. Martin reported that it was "not possible to directly identify causes for [defendant’s] behaviors . . . when he assaulted a woman," but likely the assault was a release of pressure of his "overwhelming internal strife." Dr. Martin concluded that the release of pressure and "the flashback to combat may have all surfaced simultaneously" causing unconscious actions to take place. This testimony is consistent with the argument that Kapsalis did not form the mens rea required to commit sexual assault.9

Dr. Gerson Kaplan testified in opposition to these two experts as to Kapsalis’s mental state during the assault. Dr. Kaplan, a graduate of Northwestern Medicine and a psychiatric practitioner of 30 years, testified to undermine the existence of a fugue state. Dr. Kaplan reported that, in his opinion, Kapsalis was "legally SANE. He was able to appreciate the criminality of the alleged offense, and was able to conform his conduct to the requirements of the law."10 Dr. Kaplan’s testimony supported the rebuttal that not only was Kapsalis not experiencing a disassociated state, but also that he had not consumed enough intoxicants to be voluntarily incapacitated.

The Court’s Conclusion and the Deference to the Trier of Fact

Following the war of experts, the trial judge stated his finding that there was “no question in [his] mind that Kapsalis ingested a great deal of alcohol [and ] . . . that he has some minor emotional problem.” Still, for the trial judge, Dr. Kaplan’s testimony was dispositive, leaving the trial judge “thoroughly convinced [the emotional problem] did not arise to a defense of insanity.” According to the trial judge, “this was an isolated incident induced by large quantities of alcohol."11

The trial court judge "weigh[ed] the totality of the evidence and determine[d] the credibility of witnesses," and found the Kapsalis guilty of sexual assault. The trial court judge did not need to accept the opinions of the psychiatrists proffered by the defendant and was "entitled to consider contrary opinions of the State’s expert witness."12 So long as the trial court judge’s conclusions were not "so manifestly contrary to the weight of the evidence as to indicate that the determination was based on passion or prejudice," the trial court judge as the trier of fact acted appropriately in determining  that Kapsalis was sane.13

Critical Analysis and Concluding Discussion

The Kapsalis case is indicative of the nature of social science in distinguishing between combat-related PTSD and alcohol dependence. The consistent procedure is examination by psychiatrists retained by both the defense and the prosecution who each perform fact-intensive inquiries into both the assault at issue and the defendant-veteran’s past. The psychiatrists then proffer their reports and conclusions at trial and it is left to the trial judge or the jury to balance the expert testimony and rule on the defendant-veteran’s state of mind at the time of the offense.

In a balancing process similar to Daubert, the triers of fact assess the comparative validities of scientific testimony and then assign weights to the reports of equally qualified experts. The appellate court exercises deference to these balancing determinations and will not overturn them as long as there is a factual basis in the record for the conclusion and there are no clear signs of prejudice. In effect, the triers of fact who lack technical expertise are "obligated to resolve the conflicts in expert testimony."14

However, while having judges and juries without technical qualifications assign weight to expert reports presents issues of credibility in decision making, because of the nature of the dispute between proving combat-related PTSD and alcoholism this is likely the best mechanism for assessing the validity of expert testimony. Unlike the social science predicated on tangible effects of mental disease (i.e. healthcare costs, civil disability suits), the criminal liability consequences of combat-related PTSD stem from an intangible effect of the mental health disorder: the formation of intent. Proving the ability or inability to form intent relies on fact-specific inquiries that are open to multiple interpretations as evinced in Kapsalis. These fact-specific inquiries largely rely on the authority of the expert reporting the condition that is affecting the defendant-veteran’s mens rea, and rarely are there tangible indicia of what the defendant-veteran was contemplating during the commission of a crime. Therefore, as a policy decision, it is desirable that the judge or jury without technical expertise has discretionary authority in weighing expert evidence to produce a conclusion about the defendant-veteran’s mental state that is not subject to scrutiny, because the jury (and to a lesser extent, the judge) is meant to serve as a surrogate for society writ large. Where both parties utilize qualified expert, the conclusions of the jury or the judge that an expert for one party is more qualified than the opposing expert should be given the force of society which those triers of facts are meant to represent.  

Footnote Resources:

1 The criteria for a PTSD diagnosis are available at the U.S. Department of Veterans Affairs National Center for PTSD.

2 Reasons for an increased incidence of PTSD among Vietnam veterans include the lack of unity among soldiers fighting in Vietnam, the youth of the soldiers (19.2 years average age), and the availability of drugs and alcohol. See State v. Felde, 422 So. 2d 370, 377 – 378 (1982).

3 See Felde 422 So. 2d at 377.

4 Comorbidity means the presence of concurrent disorders

5 An example of such intent is the intent to kill in a first-degree murder case or the intent to force sex in a rape offense.

6 E.g., State v. Bottrell, 14 P.3d 164, 168 – 170 (2000).

7 In the Kapsalis case, the prosecution was more aggressive than the typical "war of experts." Rather than challenging the source of the fugue state, the prosecution challenged the fugue state’s existence entirely

8 People v. Kapsalis, 186 Ill. App.3d 96, 100 (1989).

9 Kapsalis, 186 Ill. App. 3d at 101

10 Id.

11 Id.

12 People v. Eckhardt, 156 Ill. App.3d 1077.

13 Kapsalis, 186 Ill. App. 3d at 102

14 People v. Wright, 161 Ill. App.3d 967 (1987).