What are "actus reus" and "mens rea"

 Most criminal offences can be broken up into two parts that need to be satisfied in order for somebody to be convicted of the offence. These are the Actus Reus and Mens Rea.  The Actus Reus can be thought of as the physical completion of the offence which may involve creating a certain set of circumstances, causing a consequence, or failing to do something that one is legally obligated to do. This can best be explained by looking at an offence as an example -  The offence of battery requires that the defendant (D) applies unlawful force to the victim (V), with intention to do so or recklessness as to whether force is applied.  Ignoring the details of this offence and its terminology, it is clear that there are only 2 physical requirements of the offence.    1- D applies force to V   2- The force D applies to V is unlawful. These requirements are the Actus Reus as they occur in the physical world and can usually be proven by looking at the objective facts of the case.  Alternatively, the Mens Rea of an offence is the mental requirement of the defendant. This may require that they intend to do something, such as applying force to V, or that they knew that their conduct created a risk of causing something, such as the application of force to V (recklessness).  By applying this understanding of Mens Rea, we can easily see that there are 2 types of Mens Rea that will be enough to complete the offence of battery, although only one of these is required. These are as follows -   1- D intends to apply unlawful force to V   2- D forsees a risk of applying unlawful force to V and takes that risk anyway (recklessness) When looking at the definition of an offence, simply ask yourself whether an element of the offence occurs in the physical world that everyone can see. If it does, it will most likely be part of the Actus Reus. Then ask yourself whether the element of the offence occurs in the mind of D. If it does, it will most likely be part of the Mens Rea. This is easy to remember, because, the word "Actus" is similar to the word "Act" which is usually what the Actus Reus involves, such as the act of applying force in battery. Also, the word "Mens" is similar to "mind" which is where the Mens Rea occurs.