June 17, 2022 By Wallin & Klarich

The Science Behind Sleepwalking 

Sleepwalking is a parasomnia, or sleep disorder, that affects about 20 percent of people throughout their lives. While most instances of sleepwalking disappear during childhood, some people continue to sleepwalk as adults. This can be caused by a chemical imbalance, fatigue or stress, or alcohol or drug abuse. In most cases, sleepwalkers are harmless, but sometimes, parasomnia can lead to reckless behaviors or harmful actions. Research has shown that in sleepwalking adults, men are far more likely to become aggressive during these nighttime events. 

History of the Sleepwalking Defense 

The sleepwalking defense has been used to argue that a defendant cannot be culpable for his actions in a sleepwalking episode because he did not have the consciousness or intent to commit a crime. Although this defense is rarely used and generally unsuccessful, it has been effective in a few cases. The earliest use of the sleepwalking defense dates back to 1846 in the case of Massachusetts v. Tirrell, where Albert Tirrell murdered a prostitute and then set fire to the brothel. At his trial, his lawyer asserted that Tirrell was a chronic sleepwalker and committed the crime while he was asleep. Surprisingly, the jury agreed with his lawyer’s conclusion and acquitted Tirrell of all charges. 

Perhaps the most famous case of the sleepwalking defense is Regina v. Parks, where Kenneth Parks was acquitted in the murder of his mother-in-law in 1987. Apparently, Parks had driven 14 miles to his in-laws’ home and bludgeoned and stabbed his mother-in-law to death before going to the police station. At the police station, Parks seemed confused and was oblivious to the fact that he’d severed the tendons in both of his hands during the attack. His obliviousness to pain and family history of parasomnia led experts to testify that Parks had been sleepwalking during the attack and was therefore not guilty. 

Despite the defense’s success in certain cases, most attorneys are reluctant to use this strategy, as the claim of committing a crime during sleep can be seen as a last-ditch effort that lacks reliable scientific support. Furthermore, courts are hesitant to believe such a defense, as it is difficult to distinguish between a true sleepwalker and an individual who is simply using sleepwalking as an excuse to avoid prosecution. Conflicting expert testimonies on the subject further complicates the matter. 

How Does the Sleepwalking Defense Work? 

You may be asking, how does one actually assert the sleepwalking defense in court? All crimes must meet the basic elements of actus reus and mens rea; if one is lacking, the defendant cannot be charged. Actus reus is the actual voluntary act or omission. An attorney may attempt to use the sleepwalking defense to eliminate the actus reus of the crime by persuading the jury that the actor was unconscious at the time of the crime, making his acts involuntary. On the other hand, an attorney may try to eliminate the mens rea of the crime by showing that the actor did not have the necessary culpable state of mind in committing the crime because he was unconscious. 

However, a known sleepwalker still has a duty to take reasonable precautions in order to prevent harm from occurring. A defendant with a known predisposition for sleepwalking has similar responsibilities to a defendant with a known seizure disorder. People that knowingly suffer from seizure disorders can still be guilty of criminal negligence in an accident if they knew that they could experience a seizure while driving and did so anyway. Similarly, chronic sleepwalkers will still be held responsible for their actions while sleepwalking if they did not take reasonable steps to prevent harm. 

Courts have different approaches as to which side has the burden of proof. Some courts place the burden of proof on the prosecution, requiring it to prove that the defendant’s criminal act was voluntary. Other courts require the defendant to raise the sleepwalking defense as an affirmative defense. In these courts, the defendant must then prove that he is a chronic sleepwalker. Experts have suggested a balancing test in order to determine the credibility of the sleepwalking defense. These factors include: 

  • Evidence of sleepwalking during the crime 
  • Time between falling asleep and the crime 
  • Medical factors 
  • Trigger factors 
  • Circumstantial evidence 

Contact Wallin & Klarich Today 

With 40+ years of experience, Wallin & Klarich is your best choice amongst Southern California criminal defense firms. Our attorneys have helped thousands of clients, and we have the skills and resources to secure a successful outcome for you. Our experienced attorneys will evaluate the specific circumstances of your case to see whether you qualify for any defenses, so we can get your penalties reduced or even get your case completely dismissed. If you’ve been accused of a crime, contact our attorneys as soon as possible to see how we can help. 

With offices in Orange County, Riverside, San Bernardino, Victorville, Torrance, West Covina, Los Angeles, and San Diego, you are sure to find an available and convenient attorney near you. 

Discover how our team can assist you. Contact us today, toll-free at (877) 4-NO-JAIL or (877) 466-5245 for a free consultation with a skilled defense attorney.

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