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Legal Topics

Elements of crime — Legal glossary

· 6 minute read

· 6 minute read

Definition various elements of crime, related terms, and research resources for legal professionals

Legal termscriminal law • elements of crime


The main elements used in law to establish criminal activity typically include the actus reus, which refers to the criminal act itself, and mens rea, which refers to the criminal intent or mental state of the defendant at the time of the crime. Intent is a key aspect, as most white collar criminal prosecutions hinge on whether the government can prove that the defendant intentionally violated the law .

Further, specific crimes such as mail and wire fraud, or conspiracy, have their own unique set of elements. For instance, mail and wire fraud require an intent to defraud, usually for financial gain.

Conspiracy requires a conspirator’s awareness of the conspiracy and their willing participation in it . It’s important to note that these are general elements and the specific elements can vary depending on the crime and jurisdiction.

Below, we’ll explain further how a criminal act is established in law and provide insight into the complexities involved in determining whether an individual has committed a crime.


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Actus reus

Mens rea

Causation and concurrence elements

Summary and other resources


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Actus Reus

The actus reus element of a crime is the physical action required for the commission of a crime. In order for an individual to be held liable, this action must be voluntary, intentional, and unlawful.

The actus reus must also be connected to the crime’s result for liability to be assigned. An omission can also constitute an actus reus if there is a legal duty to act. This means that not taking any action when legally obligated to do so can result in criminal liability. For example, if someone fails to report a crime they know about or fails to provide aid in an emergency, they could be found guilty of committing a criminal offense.

In certain cases, an actus reus can also include a state of affairs or mental element. For instance, possession crimes require proof that the accused had knowledge and control over an item with criminal potential such as drugs or weapons. Alternatively, crimes such as fraud require proof of intent and knowledge — both mental elements — on the part of the accused in order for them to be held liable for their actions.

The actus reus element sets out clear parameters for what constitutes criminal behavior and helps prosecutors prove their case beyond reasonable doubt when it comes to convicting criminals who have broken the law.

Mens rea

Mens rea refers to the mental intent behind an act or omission that must be proven beyond reasonable doubt for it to constitute a crime. The level of intent required can differ depending on the type of offense being considered.

For general intent crimes, it is necessary to prove that the accused intended to do the act, whereas specific intent crimes require knowledge of facts which make their conduct criminal.

When assessing mens rea, three elements are typically looked at: intentionality, recklessness and negligence.

Intentional behavior indicates that someone has consciously desired a certain outcome from their actions and intended to cause it. Recklessness involves not considering potential consequences, and negligence suggests a lack of due care in relation to foreseeable risks or outcomes.

Depending on the offense in question, one or more may need to be present before assigning legal liability. Another factor related to mens rea is transferred malice. If an individual intends — or acted recklessly — towards one thing but their actions result in something else like death, they can still be held liable for this unintended consequence if there is some connection between them both.

Causal links also need to be established when determining culpability; this looks at whether there was a direct link between what happened, and any given action committed by an individual. To work out causation when multiple factors may have come into play, courts often use what’s known as ‘but-for’ test: asking whether ‘but-for’ — in other words, had it not been for — any given factor, would the outcome have occurred? If yes, then that factor has contributed directly towards causing said outcome and so forms part of establishing legal liability in court proceedings.

Both actus reus and mens rea must be present with varying levels depending on the offense — as well as evidence showing concurrence between them both — before any kind of legal accountability can be assigned.


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Causation and concurrence

When it comes to criminal liability, causation and concurrence are two fundamental elements that need to be considered. Without either of these factors being present, an act or omission cannot be deemed a crime.

The ‘but-for’ test is used to determine whether an act directly caused harm, while the concept of concurrence requires that both the actus reus and mens rea elements must occur simultaneously for a defendant to be held accountable.

There are exceptions such as transferred malice which allow for liability to extend beyond the perpetrator when they have caused harm intentionally or recklessly.

Summary and other resources

  • Criminal activity requires both actus reus (criminal act) and mens rea (criminal intent).
  • Actus reus is the physical action required for a crime and must be voluntary, intentional, and unlawful.
  • Mens rea refers to the mental intent behind an act or omission and can include intentionality, recklessness, or negligence.
  • Causation and concurrence are essential elements for criminal liability, with causation determining if an act caused harm and concurrence requiring both actus reus and mens rea to occur simultaneously.
  • Transferred malice allows for liability to extend beyond the perpetrator in cases of intentional or reckless harm.

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