Actus Reus
The Actus Reus of criminal law includes all elements of a crime except the state of mind of the defendant. Specifically, Actus Reus may consist of: conduct, result, a state of affairs, or an omission.
Conduct
The conduct itself could be criminal. For instance the act of lying under oath represents the Actus Reus of perjury. It does not matter if the lie is believed or if it had any effect on the outcome of the case, The Actus Reus of the crime is complete upon conduct.
Example of conduct crime:
Perjury
Theft
Making off without payment
Rape
Possession of drugs or a firearm
Result
The Actus Reus may relate to the result of the act or omission of the defendant.
The Act itself may not be criminal, but the result of the act may be. For instance it is not a crime to throw a stone, but if it hits a person or smashes a window it could amount to a crime. Causation must be established in all result crimes.
Examples of result crimes: Assault
Battery
ABH
Wounding and GBH
Murder & Manslaughter
Criminal damage
State of affairs
For state of affairs crimes the Actus Reus consists of 'being' rather than 'doing'. For example 'being' drunk in charge of a vehicle (Duck v peacock [1949] 1 All ER 318 Case summary) or 'being' an illegal alien (R v Larsonneur 1933) 24 Cr App R74 case summary). (Reference-Law resources online)
Omission
Occasionally an omission can result to the Actus Reus of a crime. The general rule concerning omissions is that there is no obligation for a failure to act. For instance if you see a child drowning in shallow water and you don't do anything to save that child you will not acquire criminal liability for your passivity no matter how easy it may have been for you to save the child's life. This general rule however, is subject to exceptions:
1. Statutory duty: In some situations there is a statutory duty to act, for example to provide details of insurance after a traffic accident or to notify DVLA when