Criminal Liability


AS Law (unit two) - Criminal Liability


Underlying principles of criminal liability

The traditional basis for criminal liability is an actus reus (the physical element) accompanied by the appropriate mens rea (the mental element). The general principle is that a person may not be convicted of a crime unless the prosecution has proved beyond doubt that he or she:

  • has a caused a certain event, or responsibility is to be attributed to him or her for the existence of a certain state of affairs, which is forbidden by criminal law
  • had a defined state of mind (mens rea) in relation to the event or state of affairs (actus reus)

Actus Reus:-

Actus reus literally means the "guilty act" and is made up of all the parts of the crime except the defendant's  mental state. Most crimes require the accused to commit a certain act, this is not always the case, and criminal liability can also arise through a failure to act (an omission) and from a certain type of conduct. 

Crimes of omission:-

There are five areas where such liability for omissions exists:

  • Duty arising from a contract - this occurs when a failure to perform a contractual obligation endangers life. R v Pitwood (1902) - railway crossing gate keeper opened the gate but forgot to close it and a driver was killed - he was convicted of manslaughter. 
  • Duty arising from statute - An act of parliament can make it an offence to fail to act in defined circumstances. for example Road Traffic Act 1988.
  • Voluntary assumption of duty - if someone voluntarily takes responsibility for another person, he or she also assumes the positive duty to act for the general welfare of that person. R v Stone and Dobinson (1977).
  • Duty arising from prior conduct - If the defendant accidently commits an act that causes harm and subsequently becomes aware of that danger he or she has created there arises a duty to act reasonably to avert that danger. R v Miller.
  • Public duty - a person in a public office may be under a duty to care for others. R v Dytham (1979)

Rules of causation:-

This occurs in so-called result crimes - those where the defendant's actions cause the prohibited result. 

  • Factual Causation - the factual rule of causation, referred to as the "but for" test, simply requires the prosecution to prove that "but for" the defendants act, the harm would not have occurred. R v White (1910).
  • Legal Causation - Operative or substantial cause, or intervening event reasonably foreseeable (R v Smith) - Thin skull


Ben Smith


Thankyou so much, very straight to the point. Which is great when your teacher just isn't! 

Aaliya Janjua


This is really helpful, thanks.