Defences — contributory negligence, volenti, ex turpi

The three defences in this week perform different functions and must not be assimilated. Contributory negligence is ordinarily a partial defence: the claimant proves the tort, but damages are reduced to reflect the claimant’s share in responsibility for the damage. Volenti non fit injuria is a complete defence: where the claimant freely and voluntarily accepts the legal risk of injury, no wrong is done in respect of that risk. Ex turpi causa non oritur actio, usually called illegality, is also a complete defence, but it is not founded on consent. It is a rule of legal policy which may bar a claim where allowing recovery would damage the integrity of the legal system by permitting a claimant to profit from or evade the consequences of criminal or quasi-criminal conduct.

For Part IA purposes, the organising point is that these doctrines operate after the claimant has established the primary elements of the tort. They are not substitutes for duty, breach, causation or remoteness. A defendant who says that the claimant was careless invokes contributory negligence, not absence of duty. A defendant who says the claimant agreed to run the risk invokes volenti, not necessarily lack of causation. A defendant who says the claim arises out of the claimant’s criminality invokes ex turpi, but after Patel v Mirza and Henderson v Dorset Healthcare it must be reasoned through policy, not by slogan.

The practical importance of the topic is considerable. In personal injury litigation, contributory negligence is routine: seat belts, helmets, intoxication, dangerous lifts, pedestrian misjudgment and failure to follow warnings. The main question is not whether the claimant was negligent in the abstract, but whether that fault contributed to the damage and what reduction is just and equitable. Volenti is much rarer, especially in employment and road traffic cases, because proof of full and voluntary acceptance of the legal risk is demanding. Knowledge of a danger is not enough. Ex turpi is rarer still, but conceptually difficult. It is most likely to matter where the claimant’s loss is the legal consequence of criminal punishment, participation in a joint criminal enterprise, or an attempt to shift responsibility for deliberate wrongdoing.

In Cambridge supervision and examination terms, this is a week about classification and judgment. A strong answer states which defence is being considered, gives its elements, explains its effect, and then justifies the result. Weak answers list cases under all three headings without deciding whether the facts are better characterised as carelessness, consent or illegality. The examiner is looking for disciplined sequencing: first establish the tort; secondly identify the relevant defence; thirdly ask whether it is complete or partial; fourthly explain how policy affects the result. In problem questions, apportionment under the 1945 Act should be expressed as a percentage with reasons. In essays, the best answers connect the defences to the general themes already studied: corrective justice, personal responsibility, autonomy, public policy, causation, and the limits of compensation.

At common law, contributory negligence was originally a complete defence. If the claimant’s own want of care contributed to the accident, the defendant escaped liability altogether. This all-or-nothing rule was severe. It reflected a nineteenth-century conception of responsibility in which legal liability attached only where the defendant’s fault could be treated as the effective cause of the loss. It also fitted uneasily with jury trial: findings of contributory negligence could be used to deny recovery even where the defendant’s fault was substantial. The injustice became particularly visible in industrial and transport cases, where momentary misjudgment by an injured claimant could defeat an otherwise meritorious claim.

The Law Reform (Contributory Negligence) Act 1945 transformed the position. It replaced the complete bar with apportionment. The claimant’s damages are reduced to the extent the court considers just and equitable having regard to the claimant’s share in responsibility for the damage. The language is deliberately broad. It allows the court to consider both causal potency and blameworthiness, as Stapley v Gypsum Mines illustrates. The statute thereby moved the law from binary liability to comparative responsibility. It did not, however, abolish the need to identify a relevant fault by the claimant or to prove that the fault contributed to the damage suffered.

Volenti has older roots. The Latin maxim means that no injury is done to one who consents. Historically it expressed a simple idea: the law should not protect a person against a risk which that person has freely chosen to bear. In early common law the doctrine had considerable reach. It was invoked in employment, sporting and dangerous activity cases. But modern law has narrowed it. The courts distinguish between knowledge of a risk and consent to waive legal recourse if that risk materialises. Employees, passengers and rescuers may knowingly face dangers without having genuinely accepted the legal risk. Statute and insurance policy have also reduced the practical scope of volenti, especially in road traffic and workplace contexts.

Ex turpi causa has a different lineage. It rests on the maxim that no cause of action arises from a base cause. For much of its history the doctrine was expressed in broad moral language. The courts refused to assist claimants whose actions were founded on illegal or immoral conduct. That breadth created uncertainty. Sometimes illegality operated through causation: the claimant’s own crime caused the loss. Sometimes it operated through consistency: the claimant could not deny responsibility for an offence of which he had been convicted. Sometimes it operated through deterrence or public conscience. The result was a body of cases difficult to reconcile.

The modern turning point is Patel v Mirza in contract and unjust enrichment, adopted for tort in Henderson. The Supreme Court rejected rigid reliance tests and moved towards a structured policy approach. Courts must consider the purpose of the prohibition transgressed, other relevant public policies, and whether denial of the claim is proportionate. In tort, however, the older cases remain important. Gray v Thames Trains bars recovery for losses which are the direct legal consequence of the claimant’s criminal sentence. Pitts v Hunt and Revill v Newbery show the tension between denying recovery for criminal conduct and maintaining proportionate responsibility for tortious harm. The history therefore matters because it explains why the three defences now occupy different moral and doctrinal spaces: apportionment for claimant carelessness, consent for accepted risks, and illegality for claims which would compromise the coherence of the law.

1. Contributory negligence: elements and effect. The defendant must show that the claimant was at fault and that this fault contributed to the damage. Fault is defined broadly in the 1945 Act. It includes negligence, breach of statutory duty, or other conduct which would have given rise to the old defence of contributory negligence. The claimant need not owe a duty of care to the defendant. The inquiry is whether the claimant failed to take reasonable care for his or her own safety or interests. This is why contributory negligence is sometimes described as self-regarding negligence. The standard is objective, but adjusted to the claimant’s circumstances where appropriate. Children are judged by reference to the care reasonably expected of a child of that age. In Gough v Thorne, no reduction was made against a young child who crossed the road after being signalled by an adult. Adult claimants, by contrast, may be expected to take elementary precautions, such as wearing a seat belt or avoiding obvious intoxicated danger.

1. Causation remains necessary. It is not enough that the claimant behaved badly. The claimant’s fault must have contributed to the damage in respect of which damages are claimed. This is why Froom v Butcher is important. Failure to wear a seat belt did not cause the accident, but it caused or increased the injury. The reduction therefore reflected the injury consequences, not the collision itself. Similar reasoning applies to helmets, safety harnesses and medical advice. Where the claimant’s conduct merely provides the occasion for the defendant’s tort, but does not contribute to the damage, no reduction should be made.

1. Apportionment is evaluative. Section 1(1) requires reduction to the extent the court thinks just and equitable, having regard to the claimant’s share in responsibility for the damage. Responsibility is not purely causal. It includes causal potency and moral blameworthiness. Stapley v Gypsum Mines remains the leading statement. Courts often use broad percentage reductions: 10, 15, 20, 25, 33⅓, 50 or more. The percentage must be reasoned. A claimant who fails to wear a seat belt may receive a conventional reduction of around 15 per cent if the injury would have been less serious, and 25 per cent if the injury would have been avoided. But these are guidelines, not rules of law.

The landmark cases show that the three defences are not interchangeable labels. Stapley v Gypsum Mines is the foundation for apportionment. Two mineworkers negligently decided to continue working under an unsafe roof. One was killed. The House of Lords emphasised that responsibility under the 1945 Act involves both the causative significance of the parties’ conduct and their respective blameworthiness. The case remains the proper authority for why apportionment is evaluative rather than arithmetical.

Froom v Butcher is the practical paradigm. The defendant caused a road accident; the claimant’s failure to wear a seat belt increased his injuries. Lord Denning MR set conventional reductions, distinguishing cases where the injury would have been prevented from those where it would merely have been less serious. The continuing value of Froom is not the precise mathematics alone, but its insistence that contributory negligence may relate to injury rather than accident.

Gough v Thorne illustrates the claimant-sensitive standard. A very young child who crossed the road in reliance on an adult’s signal was not contributorily negligent. The court recognised that children cannot be judged by ordinary adult standards. In examinations, the case is useful where a child, elderly person, patient or dependent claimant confronts a danger under the influence of another.

ICI v Shatwell and Morris v Murray mark the outer edge of volenti. In Shatwell, experienced workers deliberately disobeyed safety regulations and accepted the risk of premature detonation. In Morris, the claimant joined an obviously drunk pilot on a flight. Both are exceptional because the claimants appreciated the specific risk and voluntarily chose to run it in circumstances making waiver plausible. They should not be treated as everyday cases.

Reeves v Commissioner of Police of the Metropolis is indispensable because it prevents the claimant’s own deliberate act from swallowing the defendant’s duty. The police owed a duty to prevent a known suicide risk in custody. The prisoner’s suicide did not defeat the claim, though damages were reduced. The reasoning is closely connected to the scope of duty and causation material studied in earlier weeks.

The illegality cases move from older categorical reasoning to modern policy analysis. Pitts v Hunt refused recovery by a pillion passenger engaged with the rider in dangerous, drunken, unlawful motorcycling. Revill v Newbery reached a different result where a burglar was shot through a shed door: illegality reduced damages but did not extinguish liability. Gray v Thames Trains barred recovery for the consequences of a manslaughter conviction following psychiatric injury caused by the defendant’s negligence. Henderson v Dorset Healthcare then confirmed after Patel that tort illegality depends on purpose, competing policies and proportionality. Together the cases require fine judgment. The defence is strongest when the claim contradicts criminal responsibility; weaker when the defendant’s tort is a disproportionate or independent response to the claimant’s wrongdoing.

See practice questions section below.

See further reading section below.