Actus Reus Intervening Causes

R v Blaue [1975] 1 WLR 1411

Facts: The defendant stabbed a young woman four times after she refused his sexual advances. At hospital, she was advised that she needed a blood transfusion to survive. However, she refused because she was a Jehovah's Witness and accepting a transfusion would conflict with her religious beliefs. She subsequently died.

Ratio: The defendant must take the victim as he finds them (the thin skull rule). A victim's refusal of medical treatment, even for religious reasons, does not automatically break the chain of causation. The original injury remains a legal cause of death.

Application: Use where V has a particular physical, psychological or religious vulnerability that affects the consequences of D's actions. D cannot argue that V's unusual characteristics or refusal of treatment made the outcome unforeseeable.

R v Master [2007] EWCA Crim 142

Facts: The defendant was a boyfriend who stabbed his girlfriend. The case is cited in connection with the principle that a defendant must take the victim as they find them.

Ratio: A defendant cannot avoid responsibility merely because the victim's particular vulnerability or condition contributes to the seriousness of the consequences.

Application: Use alongside Blaue when considering whether a victim's vulnerability breaks the chain of causation. Blaue remains the leading authority for the thin skull principle. Check the precise factual detail against your lecture materials before relying on this case for a more specific proposition.

R v Roberts (1971) 56 Cr App R 95

Facts: The defendant gave a young woman a lift in his car. During the journey, he made unwanted sexual advances and attempted to remove her coat. Frightened, she jumped out of the moving car and suffered injuries. The defendant argued that her decision to jump broke the chain of causation.

Ratio: A victim's reaction does not break the chain if it is a natural consequence of the defendant's conduct and falls within the range of reasonably foreseeable responses. The chain may be broken if the victim's reaction is so unforeseeable or unreasonable as to be 'daft'.

Application: Use for victim escape or 'fright and flight' responses. Ask whether V's reaction was a reasonably foreseeable response to D's conduct, rather than an independent and unreasonable act.

R v Marjoram [2000] EWCA Crim 3013

Facts: The victim was threatened during an attack and attempted to escape by jumping from a window, sustaining injuries. The defendant argued that the victim's decision to jump was an intervening act.

Ratio: A victim's attempt to escape from an attack does not necessarily break the chain of causation. The response must be assessed in the circumstances created by D's conduct; a frightened reaction need not be the safest or most sensible response to remain foreseeable.

Application: Use with Roberts where V injures themselves while trying to escape D's violence or threats. Consider the situation from V's perspective and whether the reaction was within the range of reasonably foreseeable responses.

R v Dalby [1982] 1 WLR 425

Facts: The defendant supplied drugs to a friend, who subsequently injected himself and died. The defendant was charged with unlawful act manslaughter.

Ratio: Merely supplying drugs is not sufficient for unlawful act manslaughter where the victim freely self-administers them. The unlawful act must cause the relevant harm; the victim's voluntary self-administration may break the chain of causation.

Application: Use where D supplies drugs but V independently chooses to consume them. Distinguish Cato, where D directly injected the victim, and Kennedy, which confirms the significance of V's free and informed decision.

R v Kennedy (No 2) [2007] UKHL 38

Facts: The defendant prepared a syringe containing heroin and gave it to the deceased, who voluntarily injected himself. The deceased subsequently died from the effects of the drugs and alcohol.

Ratio: A fully informed and responsible adult who freely and voluntarily self-administers drugs makes an independent decision. D does not cause the administration or taking of the drug for the purposes of unlawful act manslaughter merely by supplying or preparing it. The victim's voluntary act breaks the chain of causation.

Application: Use where V freely, voluntarily and knowingly consumes drugs supplied by D. Establish whether D directly administered the drug or whether V independently self-administered it. Contrast Cato, where D injected V. The principle concerns a fully informed and responsible adult.

R v Evans [2009] EWCA Crim 650

Facts: The defendant helped procure heroin for her half-sister, Carly, who subsequently took an excessive amount and suffered a potentially fatal overdose. The defendant became aware that Carly was seriously unwell but failed to obtain medical assistance. Carly died from heroin poisoning.

Ratio: Where D creates or contributes to a life-threatening situation and knows, or ought reasonably to know, of the danger, D may come under a duty to take reasonable steps to save the victim. The failure to act may support gross negligence manslaughter.

Application: Use where D initially supplies or contributes to the victim's drug use, but the victim later overdoses. Consider whether D's subsequent failure to seek help constitutes a separate basis of liability. Distinguish the causation issue from Kennedy: Evans focuses on the duty arising once D becomes aware of the life-threatening situation.

R v Field [2026] EWCA Crim 413

Facts: Benjamin Field was convicted of murdering Peter Farquhar, who died after consuming alcohol and the sedative Dalmane. The prosecution alleged that Field had physically given him alcohol and/or Dalmane and/or smothered him. The Court of Appeal quashed the murder conviction following concerns about the jury's directions on causation and the application of Kennedy.

Ratio: The Court of Appeal's decision concerns how Kennedy applies where the defendant is alleged to have supplied or administered substances in circumstances involving deception and a victim's consumption. The precise scope of Kennedy is now before the Supreme Court; the Court of Appeal's decision should not be treated as the final word.

Application: Use when discussing the limits of Kennedy, particularly whether a victim's apparent voluntary consumption necessarily breaks the chain where D may have deceived or manipulated them. The Supreme Court appeal is awaiting judgment, so distinguish the Court of Appeal ruling from the final law.

R v Wallace [2018] EWCA Crim 690

Facts: The defendant threw sulphuric acid over her former partner, Mark van Dongen, causing catastrophic injuries, including paralysis and severe, constant suffering. He later travelled to Belgium and underwent voluntary euthanasia, lawfully administered by doctors. The trial judge ruled that his decision and the doctors' actions broke the chain of causation and withdrew the murder charge from the jury.

Ratio: The Court of Appeal held that the jury could properly find that the defendant's attack remained a significant and operating cause of death. The victim's decision to undergo euthanasia and the doctors' intervention did not necessarily break the chain because they were closely connected to the injuries inflicted by D.

Application: Use where V makes a later decision that contributes to their death, particularly where that decision arises directly from D's injuries. The case does not establish that euthanasia can never break the chain; the question depends on the circumstances and whether D's conduct remains a significant and operating cause.

R v Martin (1881) 8 QBD 54

Facts: The defendant deliberately put out the lights on the stairs of a theatre and obstructed an exit, intending to cause panic among the audience. A panic followed, and people were injured in the resulting rush.

Ratio: D may be responsible for injuries caused through the reactions of other people where those reactions are a consequence of D's conduct. D does not need to inflict the physical injury directly.

Application: Use where D creates a dangerous situation that causes a crowd or other people to react and injure someone. Consider whether the resulting reaction was sufficiently connected to D's original conduct.

R v Pagett (1983) 76 Cr App R 279

Facts: The defendant, armed with a shotgun, used his pregnant girlfriend as a human shield during a confrontation with armed police. He fired at the police, who returned fire in reasonable self-defence. A police bullet struck and killed the girlfriend. The defendant argued that the police officers' actions broke the chain of causation.

Ratio: A reasonable act performed for self-preservation, or an act performed in the execution of a legal duty, does not normally constitute a novus actus interveniens. The police's reasonable response to D's actions did not break the chain.

Application: Use where a third party intervenes in response to D's dangerous conduct, particularly where the third party acts reasonably in self-defence or in performing a legal duty. D cannot normally escape liability merely because another person's reasonable response immediately caused the injury.

R v A [2020] EWCA Crim 407

Facts: A stopped her car on the M1 hard shoulder at night and remained there for approximately 15 minutes without displaying hazard lights. Another driver, whose lorry veered across the motorway, collided with the stationary car, killing a passenger. The trial judge ruled that the lorry driver's dangerous driving was a new intervening act and that A's conduct had not legally caused the death.

Ratio: The Court of Appeal held that the precise manner in which the intervening event occurred did not have to be reasonably foreseeable. It was sufficient to consider whether the general nature of the intervening act and the risk of harm were reasonably foreseeable. The prosecution appeal was allowed and a retrial ordered.

Application: Use where a third party's dangerous or negligent conduct intervenes. Ask whether the general type of intervening event and risk of harm could reasonably have been anticipated, rather than requiring D to foresee the exact sequence of events. The Court of Appeal ordered a retrial; it did not itself find A guilty.

R v Smith [1959] 2 QB 35

Facts: The defendant, a soldier, stabbed another soldier during a fight. While being taken for medical treatment, the victim was dropped twice and received negligent treatment. Medical staff failed to recognise that his lung had been punctured, and he subsequently died.

Ratio: The original injury remains a legal cause of death if it is still an operating and substantial cause at the time of death. Negligent medical treatment does not automatically break the chain unless it is so overwhelming that the original injury becomes merely part of the history.

Application: Use where medical negligence occurs after D injures V. Ask whether D's original injury remained an operating and substantial cause of death despite the medical treatment.

R v Cheshire [1991] 1 WLR 844

Facts: The defendant shot the victim in the leg and stomach. During hospital treatment, the victim developed breathing difficulties and underwent a tracheotomy. Medical staff negligently failed to recognise complications arising from the procedure, and the victim died approximately two months after the shooting.

Ratio: Medical negligence will only break the chain of causation where it is so independent of D's original act and so potent in causing death that D's contribution becomes insignificant. D's act need not be the sole or main cause of death.

Application: Use as the leading modern authority where medical negligence is alleged to have intervened. The fact that medical treatment was negligent or even the immediate cause of death is not enough by itself to break the chain.

R v Jordan (1956) 40 Cr App R 152

Facts: The defendant stabbed the victim, who was taken to hospital. The original wound had largely healed, but medical staff administered excessive intravenous fluids and medication to which the victim was allergic, despite knowing about the allergy. The victim died as a result of the treatment.

Ratio: Exceptionally, palpably wrong medical treatment may break the chain of causation where it becomes the direct and immediate cause of death and the original injury is no longer an operating cause.

Application: Use as the exceptional contrast to Smith and Cheshire. The original injury must have ceased to be an operating cause, and the medical treatment must be sufficiently independent and potent to displace D's contribution. Jordan is an exceptional case, not the ordinary rule.