causation in law


There is substantial uncertainty in the legal community regarding the correct interpretation of the concept of causation - did an act or ommission cause the outcome under consideration - including whether it is a matter of common sense, a question of fact or of law.

The result of the search for guidance is a branch of the law ‘which is highly discretionary and unpredictable’ (Chapel V Hart (1998)).

The concept of causation is integral to the prosecution of offences, where the prohibited act (actus reus) must be proved ‘beyond reasonable doubt’. In addition, except in offences of ‘strict liability’, the accused must also be proven to have acted with the required ‘guilty mind’ (mens rea).

There are various approaches to the determination of causation, but essentially one must pass through a series of ‘stages’, or ask a series of questions.

The first stage is to assess whether there is a ‘factual link’ between the defendant’s conduct, and the victim’s death (Lanham 2002). This can also be seen as the ‘cause in fact’, and requires the application of the so-called ‘but for test’, i.e. the prohibited result would not have happened, but for the act or omission of the defendant (R V Dalloway (1847)).

The satisfaction of the ‘but for’ test fulfils the criterion of ‘necessity’; the act (or omission) is necessary for the outcome to occur. Since there is no requirement in law for a ‘cause’ to be exclusive it is possible for an act (or omission) to be insufficient on its own to effect the outcome so long as it has some effect (more than ‘de minimis’).

Having established the ‘factual link’, one must then consider whether the link is sufficiently strong to attribute ‘causation’.

Lanham (2002) recommends the consideration of the circumstances in question against a general ‘formula’, followed by any specific ‘sub rules’ that may be applicable. Finally a consideration of the effects of ‘intention’, ‘foresight’ and ‘forseeability’ may be relevant.

For a cause to be a ‘legal cause’, and thus to satisfy the ‘general formula’, it must be ‘substantial’, and an ‘operating cause’ (R V Smith (1959)), or ‘significant’.

Where a death has resulted, and if an act contributed significantly to that death, that is sufficient – it need not be the sole or even the principle cause of death (R V Cato (1976)).

When considering whether an act is ‘substantial’ or ‘significant’, Coronial law would suggest that the act ‘more than minimally, negligibly or trivially contributed to the death’ (R V HM Coroner for Exeter and East Devon; ex parte Palmer (1997)).

One must also consider the effect of ‘special sub groups’ – namely that of ‘physical infirmity’ and/ or the reaction of the victim to threats.

A principle of criminal law is that the defendant ‘takes his victim as he finds him’. This is often enunciated with the example of a hypothetical victim of an assault who is particularly susceptible to severe head injury following a minor blow due to an abnormally ‘thin skull’. A defendant cannot escape responsibility for the victim’s death as a result of that abnormality, should he strike him on the head. This general principle was described in R V Hayward (1908) and confirmed more recently in R V Blaue (1975).

This general rule has been interpreted as referring to physical peculiarities of a victim which might hasten death, although in Blaue it was suggested that the rule referred to the ‘whole man and not just the physical man’.

An unreasonable reaction of a victim to ‘threats’ has been held to ‘break the chain of causation’ e.g. DPP V Daley (1979) in contrast to older cases such as R V Halliday (1889), whilst a refusal to have a blood transfusion following a stab wound to the chest was held not to break this chain, implying that even if the victim’s actions in response to an injury are considered to be ‘unreasonable’ in the circumstances, they may still be irrelevant to the issue of the assailant’s culpability. (R V Blaue).

Having established a ‘factual link’ and ‘legal cause’, the legal assessment of ‘causation’ must consider issues relating to ‘forseeability’, ‘foresight’ and ‘intention’.

When death may be a ‘real possibility’ of one’s actions (or omissions), or where one ‘intends’ to cause death, one can be held liable for those actions (or omissions). However, the reverse is not necessarily true (Blaue).

Of particular relevance to our case study is the Court of Appeal’s judgment or ratio decidendi in Dawson, Nolan and Walsley (1985).

Here 3 men were convicted of manslaughter following an armed robbery. The victim had a ‘bad heart’ and died of a heart attack after the robbery. It was held that they were not responsible for the death, which they could not have foreseen, as they did not know about the victim’s poor state of health. Their conviction for manslaughter was quashed, whilst convictions for armed robbery were upheld.



  • Chappel V Hart (1998) 195 CLR 232
  • Dawson, Nolan and Walmsley (1985) 81 Cr App R 150
  • Lanham D. Principles of causation in criminal law’, Chapter 10 in ‘Causation in law and medicine’, Freckleton I. And Mendelson D. (Ed) 2002 Dartmouth Publishing Company, Aldershot England
  • R V Blaue (1975) 1 WLR 1411
  • R V Cato (1976) 62 Cr App R 41
  • R V Daley (1979) 69 Cr App R 39
  • R V Dalloway (1847) 2 Cox CC 273
  • R V Halliday (1889) 61 LT 701
  • R V Hayward (1908) 1 Cox CC 692
  • R V HM Coroner for Exeter and East Devon; ex parte Palmer (unreported Court of Appeal 10/12/1997)
  • R V Smith (1959) 2 QB 36

causation in the law


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