The Defense "Rests" Its Case:
Sleep-Related Violence in the Judicial System

Written by John Leganski, Spring 2010

Can a sleepwalker commit murder? In the strangest of court cases, lawmakers and the public are left to rely on experts and research when determining the validity of sleep disorders as a defense for violent actions, including murder.

A man drives 14 miles to the home of his in-laws. He enters with a key he was given. Inside, the man bludgeons his mother-in-law with a tire iron and attempts to strangle his father-in-law. The woman dies, while her husband barely survives the attack.

The man, Kenneth Parks, then drives to a nearby police station, where he tells officers that he thinks he may have killed someone.

Less than a year later, a Canadian Jury hears the man's case and hands down a verdict on the charge of murder: not guilty.

Kenneth Parks walks free, thanks largely in part to his defense attorneys' ability to prove that Parks was, in fact, asleep at the time of the incident.[1]

The Legal Standpoint

Outside the courtroom, the scales always favor sleep!

The Kenneth Parks case is just one of many involving a defense of "homicidal somnambulism," the act of killing another while sleepwalking. This defense is one of automatism, or complex behavior being performed without conscious awareness or intent.

When applied in the courtroom, automatism takes one of two forms: non-insane or insane. Non-insane automatism is the result of external or extrinsic factors, while insane automatism is the result of an internal cause. Currently, most sleep-related episodes of violence are considered to be instances of non-insane automatism.

"If sleepwalking is deemed an insane automatism, then a significant percentage of the general population is legally insane," stated Dr. Mark Mahowald in his 2005 publication on sleep-related violence.[2]

Because sleepwalking is so prevalent, jurors could not reasonably interpret Parks' episode under the insane classification of the law. As such, Parks' defense plea was not regarded as a plea of insanity, thereby eliminating the option of sentencing him to a psychiatric hospital.

The Circumstances

Accordingly, the monumental and controversial decision in the Parks case was not one made hastily. Jurors had to consider a variety of factors, while relying heavily on the opinions of sleep medicine specialists, in an attempt to discern if Parks' story--that he was actually sleepwalking when he attacked his in-laws--was both plausible and genuine.

Ken Parks - Violence During Sleep Ken Parks walks free after the high-profile 1987 murder case that was appealed up to the Canadian Supreme Court.

One pertinent factor was Parks' high-level of stress around the time of the incident. He had recently accrued some very large gambling debts and was unemployed. He had hardly slept in the days leading up to the incident, and the defense argued that these circumstances led Parks to develop the insomnia, which can exacerbate the severity of a sleepwalking episode.

Other considerations included Parks' and his family's history of sleepwalking; an amnesia about the events, particularly about the deep cuts on his hands that he did not notice until arriving at the police station; and finally, a convincing testimony by his wife that claimed Parks would have no motive to kill her parents.

Combined, these factors swayed the jury. It was decided that Parks' actions were the result of a sleep disorder of arousal. These disorders constitute a strange mixture of wakefulness and non-REM sleep in such a way that allows for one to perform complex behaviors without conscious awareness of those behaviors. And because the acts are performed without awareness, they are also performed without responsibility.[3]

(Learn more about the various types of sleep disorders.)

The decision was appealed to the Canadian Supreme Court, which upheld the initial "not guilty" ruling.

Since the Parks case, significant sleep research has been devoted to further pinpointing the causes of sleep-related violence. Recent studies reveal that over 2% of the adult population reports violent behaviors arising from the sleep period, far higher than previously estimated.[4]

Some other general trends associated with individuals suffering from sleep-related violence episodes include:

  • Amnesia for most of the event
  • Seemingly senseless behavior, without motivation
  • Perplexity and horror immediately following the event, with no attempt to conceal or cover up the events
  • Events fit the timing after sleep onset and the duration of the proposed explanation
  • Accompanying sleep deprivation
  • Episode last only around 30 minutes
  • Evidence of a sleep disorder (based on medical history or laboratory examination)[5]

Furthermore, it has been cited that sleep-related violence is more common in males than females, and patients most often fall between the ages of 15 and 44.[6]

In addition to sleepwalking and disorders of arousal, researches have cited other neurological conditions commonly associated with violent behaviors during sleep.

In REM sleep behavior disorder, for example, there is an absence of REM sleep atonia, which normally propagates sleep paralysis. This allows the individual to act out his or her dreams, in potentially dangerous manners.

One tragic example is the case of Brian Thomas, of South Wales, who strangled his wife in his sleep as he dreamed that he was fighting an intruder. His story was met with equal skepticism. But in the end-after psychiatrists acknowledged he suffered from REM sleep behavior disorder-Thomas was acquitted of all charges.

The Other Side of the Coin

Unfortunately, some individuals have attempted to abuse the automatism defense in their favor.

In Arizona v. Falater, the defendant Scott Falater was convicted of murder after he brutally stabbed his wife with a knife and held her head under the water of their backyard pool.

Falater claimed to be sleep deprived, with a history of sleepwalking. Still, prosecutors questioned why he attempted to conceal the evidence in his car. Witnesses also spotted him motioning to his dog to lie down in the middle of the attack, suggesting some level of consciousness. The court ultimately found Falater guilty of first-degree murder.

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Moreover, beyond those trends previously mentioned, sleep experts and judges are very hesitant to release details about specific conditions that permit sleep-related violence, out of fear of copycat killings and illegitimate defense pleas.

Overall, the cases involving sleep-related violence and sleep disorders are among the most unusual in today's legal system. They have been judged differently in every region, and have varied based on the slightest of circumstances. And in all likelihood, such cases will remain highly subjective-a relative gray-area in the judicial system-until further sleep research can accurately determine an individual's consciousness at the time of an episode.

To better understand the spectrum of extreme overt behaviors that can lead to cases like those discussed above, experts have formed the Sleep Forensics Association. You can check out their website to learn more about them and other case studies involving violence during sleep.

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  1. "Man Acquitted Of Sleepwalking Murder Running For School Trustee In Durham." CityNews. 27 Oct. 2006. Web. .
  2. Mahowald, Mark W., Carlos H. Schenck, and Michel A. Cramer Bornemann. "Sleep-related Violence." Current Neurology and Neuroscience Reports 5 (2005): 153-58. Springerlink. Web. .
  3. Ibid.
  4. Ibid.
  5. Kushida, Clete A. "Introduction to Parasomnias." Sleep and Dreams Class. Cubberley Auditorium, Stanford. 30 Apr. 2010. Lecture.
  6. Mahowald, Mark W. "Sleep-related Violence."
  7. "'Dream' Man Free After Killing Wife." Express. 20 Nov. 2009. Web. .
  8. Lyon, Lindsay. "7 Criminal Cases That Invoked the 'Sleepwalking Defense'" U.S. News and World Report: Health. 8 May 2009. Web. .

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