Among the handful of syllabus components in the introductory law course I took this August, one that particularly intrigued me was that of ‘actus reus and mens rea’; two fundamental elements of criminal liability. The Oxford English Dictionary defines actus reus as “the physical, external element of a crime, encompassing the prohibited conduct, consequences, or surrounding circumstances that the law seeks to prevent,” and mens rea as “the mental or fault element necessary to establish criminal responsibility”. In short, actus reus refers to the guilty act, and mens rea refers to the guilty mind. 

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To help in actualizing the two concepts, we explored different scenarios — from the simplest: a man throwing a brick at a window — to more complex ones, such as accidental embezzlement. This was where I was first met with the obscurity of law. I discovered that, in reaching a verdict, a more complex, mental element must be considered, rather than simply the ultimate act of crime. For this reason, I have decided to continue my exploration of the two notions, examining their impact on the criminal justice system through two possible real-world scenarios.

 

To build a bedrock understanding of the implications of the actus reus and mens rea, consider the brick and window scenario. Picture a man on pavement, tossing a brick into a store front. The actus reus (guilty act) is evident in the physical motion of his arm; throwing the brick towards the window and ultimately shattering it. Yet, in pursuing a just legal outcome, judges dig deeper, considering what ran through his head in the moment to determine punishment. Intent shapes law here, not just action. Suppose that the man flung the brick through the window on purpose, perhaps with the intent of entering the store and looting it. In this case, he has committed a crime. However, if his foot slipped and the object moved without control, damage still happened, though nobody really meant it. For this particular instance, the actus reus is still present, though the mens rea is not. As a result, the man may be absolved of criminal intent, with the court reaching the verdict that he is not guilty. This doesn’t necessarily mean that he is off the hook. He still faces the threat of being sued in civil court for negligence, resulting in an obligation to pay for the damages — though he avoids criminal conviction. 

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However, the concepts of actus reus and mens rea are subject to ambiguity. The digital age introduces a new layer of complexity in the administration of justice. Picture a bank employee by the name of Sam. Sam tries his hand at coding, building a program that steals tiny fractions of a cent from customer accounts. Instead of running the program, he saves the file to his computer, too hesitant to carry it out. A week later, during an ordinary, legal software upgrade, he accidentally selects this file, launching it instead. Just as in the previous scenario, the actus reus is clear; the illegal program was run and funds ultimately diverted. However, determining the mens rea is much more complicated here. Though it could be said that Sam lacked a guilty mind as he initially chose not to execute the code, a prosecutor could argue the mens rea was established the moment he created the malicious script. In any criminal trial, the prosecution bears the burden of proof, meaning that it is their responsibility to convince the court of the defendant’s guilty mind. Proving such thing is a ‘legal headache’ — it is notoriously difficult as it requires proving the thoughts of the defendant beyond reasonable doubt.

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Ultimately, actus reus and mens rea reveal that determining criminal liability is a multi-layered challenge. While actus reus shows the physical element of a crime (which is easier to identify), mens rea forces courts to consider human intent, allowing for a more nuanced evaluation of criminal accountability. It aligns the law with morality, adding a layer of sophistication to the criminal justice system, though the process of proving a defendant's personal intent is not straightforward — just as in the scenario of Sam’s unlawful program. There is ongoing debate within the law community regarding whether or not the incorporation of mens rea is necessary — with traditionalists worrying that taking out the need for a "guilty mind" could result in unfair punishment for honest mistakes, while others suggest that in an increasingly complex society (in particular, the digital age), stricter administration of justice is required to preserve public safety and punish crimes for what they are. 

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