Fault, as a legal term, refers to legal blameworthiness and responsibility in each area of law. It refers to both the actus reus and the mental state of the defendant. The basic principle is that a defendant should be able to contemplate the harm that his actions may cause, and therefore should aim to avoid such actions. Different forms of liability employ different notions of fault, in some there is no need to prove fault, but the absence of it.
In criminal law, the mens rea is used to decide if the defendant has criminal intent when he commits the act and, if so, he is therefore liable for the crime. However, this is not necessary for strict liability offences, where no particular state of mind is required to satisfy the burden of proof.
Actus reus element
Most requirements for a successful actus reus require a voluntary act, or omission, for evidence of fault. There is also a requirement for a clear causation, there is no liability or fault if the defendant was not actually the sole cause of the act, this is so if there was an intervention of a third party, an unexpected natural event, or the victim's own act. Either of these can remove the legal blame from the defendant and remove the fault.
Automatism
If the criminal act is caused by an act of automatism, it means the act was caused by an involuntary movement of the limbs, and not controlled by neuron stimulation, removing the blameworthiness from the defendant. This was seen in the case of Hill V. Baxter (1958) where the defendant injured a person by crashing his car into them. He argued that his action was not voluntary because he was unaware of what happened. However, he was found guilty because the judge held that sleepiness or drowsiness when driving does not amount to automatism.
Duress
In the case of duress, the defendant has committed the act in response to a threat of death or serious personal injury to himself or a loved one, or someone towards whom he feels responsible. Therefore he is removed of fault as his actions were done to prevent such harm being done. It would be considered unfair to place the defendant at fault of a criminal action which he committed under duress.
Liability
In such cases of a "state-of-affairs" crimes, the defendant may be found liable even if he or she did not purposefully or voluntarily commit a criminal act. This is seen in R v Larsonneur (1933), where the defendant was French and entered the UK. She then tried to marry a British citizen, after which she would have gained British citizenship, which she could never be subsequently deprived of. However, the marriage was refused and she was ordered to leave the UK that day (March 22). Instead, she went to the Irish Free State seeking a priest there to marry her and the man, George Drayton. No priest could be found and the Irish police ordered her to leave by April 17 under the Irish Constitution. Larsonneur still did not leave and on April 20 was taken into custody by Irish police where they were forced to deport her back from whence she had come, the UK. On arrival in the UK, she was arrested for being an 'illegal alien'. The defendant was not at fault as she did not intentionally re-enter the UK under the Alien Act; however she was still liable for the crime under Alien Act, as there was no need to prove the act was voluntary. This was also seen in the case of Winzar v Chief Constable of Kent (1983) where the defendant was admitted to hospital by a friend who was worried for his health. However when the hospital realized he was merely drunk to the point of being semi – unconscious, they discharged him from the hospital. The defendant, because of his intoxicated state, could not get home, and was liable for drunk and disorderly conduct. Even though he did not have intention for the crime, nor was he at fault, because the crime been one of state of affairs he was liable and charged as such.
Causation
There is also an issue of causation, in this the courts look at both factual causation and legal causation. Factual causation uses the 'but for' test, asking: 'but for the defendant's act, would the result still have occurred?' If it would have occurred regardless of the defendant's acts, there is no factual causation and the defendant is not guilty. Factual causation was effectively established in the legal case of Pagett [1983]. However, in the case of White [1910] the result would still have occurred 'but for' the defendant's actions, so there was no criminal liability. Legal causation uses the 'operative and substantial' test. The defendant's acts must be the 'operative and substantial' cause of the result, as seen in the case of Smith [1959].