Criminal Law

Actus Reus

Actus reus, or a "guilty act," is the physical act that is required for a crime to have been committed.

It is generally considered implicitly implied that the acts must be voluntary—done by a willed bodily movement.


Possession usually requires the defendant's to procuring, receiving, or failing to dispose of the property to be the voluntary act.

Possession can also be constructive if one has power over an item, even if he has no physically possessed it. This requires him to have:

  1. knowledge of the property,
  2. the ability to control the property, and
  3. intent to exert control over the property.

Omissions are the opposite of acts; they are the failure to act. Generally, an omission cannot be a crime, but in some circumstances, not acting can satisfy the requirement of actus reus.

A conviction can only be based on an omission when the defendant had a legal duty to act.


Bystanders usually fall under the general rule of omissions and are not liable for failing to stop a crime. Exceptions may exist if a bystander has a legal duty to act, as in an omission, or if the bystander "encouraged" the crime and thereby became an accomplice.