Causation

Was the Ds breach a cause, in fact, of the harm suffered by the P?
 * **s.51(1)(a)** – there will be factual causation if the Ds breach was a necessary condition of the Ps harm. The Ds negligent act does not have to be the only cause of the Ps injury. It is enough if the Ds breach is a necessary cause.
 * If there was more than one responsible person, the P can recover from one, or both, but cannot receive more than 100%: **//Chapman v Hearse//**.


 * __The ‘But For’ test__**
 * TEST** – Would the Ps injury not have occurred //but for// the D’s breach of duty?: **//Barnett v Chelsey Pentington Hospital//.**
 * **s.51(2) –** Where the ‘but for’ test is not satisfied in deciding whether factual causation is made out, the court must decide whether responsibility for the harm should be imposed on the negligent party.
 * **s.51(3) –** Consider what the actual P would have done had the D not been negligent, not what the reasonable person would have done. Must look at all the events to determine the Ps actions if given the right advice.
 * The ‘But For’ Test has an important role to play, but is not the exclusive test of factual causation. Commonsense, as well as value judgements and policy considerations are also relevant: **//March v Stamare//**.


 * à When the ‘But For’ Test is not satisfied –**
 * **s.51(2) Wrongs Act –** where ‘but for’ is not satisfied, court can still find breach was the factual cause of the harm if policy dictates that it should.

__Establish Increased Risk as a Cause__
 * The court can also modify the ‘But For’ Test where the court cannot be sure that the Ds act caused the harm, but it can be said that the Ds breach increased the risk of the P suffering material harm: **//McGhee v National Coal Board//**.
 * If Ds breach materially increases the risk of harm, it will only show factual causation on a prima facie basis – it is still open for the D to show that they did not cause the harm: **//Chappel v Hart//**
 * Increased risk is not sufficient to establish causation when there are many possible causes of the injury and only one of which was related to Ds breach of duty: **//Wilsher’s case.//** HOWEVER, if the various possible causes are similar in nature, the increased risk will be sufficient: **//Barker v Corus//**.
 * D will only be liable for the portion of the harm suffered as a result of that increased risk: **//Barker v Corus//**.


 * à Multiple Sufficient Causes**
 * Cases where there are two or more things that led to the P dying, each of which is independent of the other, but each of which is sufficient to cause the death or injury: **//Fairchild v Glenhaven Funeral Homes// ***(e.g. two employers expose same employee to asbestos, employee develops lung cancer).
 * **//Performance Cars v Abraham//**: D crashed into Ps car. The car was already damaged, and no subsequent work was required. The estimated price of repair was the same as that awarded for the initial crash.

__Medical Cases__: **//Chappel v Hart// per Kirby** Ps often have trouble establishing causation in medical negligence cases. As a result, if the P shows that:
 * D breached the duty of care; This increased the risk that P would suffer an injury, and; P did in fact suffer that injury, then a prima facie case of causation is established.


 * __Take the P as You Find them__**
 * The damage caused by the Ds negligence must be assessed by reference to the specific P. Where the P has already been harmed, the D will only be liabe for any additional damage caused by his negligence.
 * e.g. D crashes into a car that is already damaged, D would only be liable for the further damage to the car, not the pre-existing damage: **//Performance Cars v Abraham//**.


 * __Legal Causation__**
 * à Which of the factual causes are legally relevant?**
 * The court uses common sense, and regards voluntary human action as particularly significant, so any voluntary action by the d that contributed to Ps injury is likely to be treated by the court as a relevant legal cause of injury.


 * à What is the effect of an intervening act between the Ds breach and Ps injury?**
 * **s.51(1)(b) –** in order for there to be causation, it must be appropriate for the scope of the person’s liability to extend to the harm caused. If an intervening act breaks the chain, it will not be appropriate for liability to extend to the harm caused because of an intervening act (//novus actus interveniens)//.
 * **s.51(4)** – in dealing with the scope of liability, the court is to consider whether or not and why responsibility should be imposed on the negligent party.
 * Not all intervening acts will break the chain of causation. Must be unwarrantable and disturb the sequence of events: **//The Oropesa// per Lord Wright**//.//
 * When there are reasons in common sense, logic or policy for refusing to regard the Ds negligence as a cause of the Ps loss an intervening act will break the chain of causation: **//March v Stramare// per Mason.**
 * The prevailing approach is that an intervening act will break the chain of causation if it is either: (1) voluntary human action; or (2) a causally independent event: **//Haber v Walker//** per Smith J

The chain of causation will only be broken if:
 * à Causally Independent events**
 * The natural event is casually independent of the Ds negligence; and
 * The conjunction of this event with the Ds negligence is so unlikely as to be considered a coincidence: **//Environment Agency v Empress Car//**.

__Voluntary Human Action__
 * Occurs when the actor has exercised free choice and when that choice is not made under substantial pressure created by the Ds negligence: **//Haber v Walker//**.
 * VHA will not break the chain of causation if the D was under a duty not to expose the P to the risk of injury arising from voluntary human conduct: **//March v Stramare//** **per Mason**.
 * Volunariness requires the intervening act to be ‘free, deliberate and informed’: **//Bennett//**

__Foreseeability Approach is not applicable__
 * If an intervening act was foreseeable then it can’t break the chain of causation
 * Foreseeability is only relevant to remoteness, not causation: **//Chapman v Hurse//**

Need to distinguish between:
 * à Loss of a chance**
 * Cases where the Ds breach of duty causes harm to the P; and
 * Cases where the Ds breach of duty deprives the P of a chance to recover from an existing harm.

__Negligent acts by a 3rd Party__
 * à Negligent Acts by someone other than the D**
 * Negligence by a 3rd Party may break the chain of causation. However, the negligent medical treatment will not break the chain of causation unless it is ‘grossly negligent’ or ‘inexcusably bad’: **//Mahoney v Kruschich Constructions//**.

__Negligent acts by the P__
 * Generally the focus is on contributory negligence as a defence: **//March v Stromare//.**

__Subsequent negligent conduct__
 * Subsequent negligent conduct may sever the causal connection.
 * E.g. D blocks tunnel, a policemen goes the other way down the tunnel to close it and is injured: **//Knightley v Johns//**


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