Actus reus

The Actus Reus is part of the behaviour describing a criminal act. It describes the physical elements in the criminal act. All criminal acts contain an Actus Reus, crimes which do not are known as Strict liability crimes
It is contrasted from the Mens rea which details the mind or intentions of the accused.
==Physical element==
The Actus is either an act, or an omission, or a state of affairs.  They can also be thought of as conduct, circumstance or and result actuses, they may, or may not, be multiply present in a single crime
===Acts===
Acts usually ban a certain result. Eg- Homocide crimes ban killing another person. This can be done direct, or through an agent.
In HM v Mitchel (1856), a man who was assaulting his wife was found guilty killing their daughter, who in turn died of suffocation from the wife trying to shield the daughter.
An act must be voluntary. In Simon Fraser the accused attacked another whilst sleepwalking, this was not held to be an act for the purposes of a crime.
Reflex actions, as in Jesspo v Johnstone (1991) where a teacher hitting a student as a result of a flinch, are not considered voluntary acts and also do not meet the definition of an act.
===Omission===
Omission offences apply where there is a duty to act, but this is not discharged. 
As a general rule there is a great reluctance to create crimes out of omissions. Its generally considered an infringement on personal liberty to do so (but is a feature of Civil law systems where a "Duty to rescue" is common). Turning off life support, or refusing to treat a patient do not count as acts. 
There is no general duty to report or prevent a crime (in HM Advocate v Kerr (1871), the accused failed to report a gang rape but no crime was found). However, the Terrorism Act 2000 does place a duty if int he course of business or employment such things are suspected, and the Criminal Justice and Licensing act places a similar burden for when organised crime is suspected.
There is often difficulty in causing Causation in omission crimes.
Duties to act only exist in certain circumstances
In Patterson v Lees (1999) a Babysitter was found not guilty of Shameless Indency for not stopping some children in his care from watching a pornographic video.
There is no duty to disclose to an officer searching you any weapons or other risks that your possessions may present. Marlin v Clark (2002) presented a case where during a stop and search, the accused when asked "are you caring any sharps" responded "there's always a chance", the officer was then subsequently injured. There was found to be no duty on the part of a searchee to disclose or assist the police as this would be a breach of the right to remain silent (however, had the accused instead answered no, this would have been a potential crime).
Omission crimes can be of conduct, such as how the The Road Traffic Act 1988 makes it an offence to refuse to cooperate with an alcohol breath test, or through result in the example of Culpable death where the accused has a duty to act
====Where does a duty to act exist====
A duty to act requires requires some of special situation, such as
*A special/personal relationship
:*Parent/Child ([Bone v HM Advocate], [Gibbins v Proctor])
:*Possibly Spouses ([R v Russel] - English case law only)
:*Possibly siblings ([R v Evans (Gemma)] - English case law only)
:*Doctor Patient Adomako
:*Possibly Friends (Lewin v CPS - English case law only)
*A voluntary assumed duty
:*Through a Contract 
:*Through Conduct (R v Instan)
:*Through a special position eg- Police. (Bonar & Hoss v Macleod)
*An omission following a previous dangerous act
:In R v Miller (1983) a person who woke up to find that their cigarette had begun to smoulder, and simply moved to another room was found to be liable for fire raising by omission for their failure to act following the dangerous situation they created. 
::McCue v Currie (2004) looked at a similar situation, but the reason that liability was not attached is unclear
:McPhail v Clark involved a road traffic accident caused by smoke from a fire that McPhail was in charge of.
====Discharging that duty====
The test to determine if a duty has been discharged is subjective - it looks at what the person can reasonably have done, and if they have done it. For example In [Bone v HM Advocate] whilst a pregnant mother was found to have a duty to intervene to save a child, she was not considered able to in her state.
===State of Affairs===
State of Affairs crimes include Possession of banned items, or being "Drunk and incapable". These are typically strict liability crimes with no mens rea requirement.
==Examples==
In this example, the "Act of causing the destruction of life" is the Actus Reus.
Rape contains both a conduct (Penetration) and a circumstance (lack of consent) actus to be shown in order to be proven. Fraud however has both a conduct, and a result actus.
Category:Criminal law