The Defendant threw a lit squib into a market place. To avoid injury the stallholders threw the squib from stall to stall until eventually it exploded, blinding the Plaintiff. The Defendant was found to be liable, and the stallholders did not break the chain of causation. Stansbie v Troman  2 KB 48. A decorator left a house to go to the shops. During this time, having left the front door ajar, a thief walked in a burgled the house. He claimed that he could not be held liable for the act of thieves. The court disagreed. He was found liable for it, as the chain of causation had not been broken. However, if the thief had been caught he would not have been able to claim that it was the decorators' fault he burgled the place by leaving the door open.
Causation is usually a case of common sense. However, it is a matter of law in complex situations. Each situation must be assessed individually; the players, the situation, the acts done, the omissions all contribute to an incident. However, common sense must be used when assessing it. Knightley v Johns  1 WLR 349 The 1st Defendant negligently caused a car accident at the opening of a tunnel.
The 2nd Defendant was a copper in charge at the scene. He's negligently forgotten to close the tunnel, and so sent the Plaintiff to go and close it. Whilst driving down the tunnel, he was hit by another car. He claimed that the 1st Defendant was more to blame. It was said that the chain of causation had been broken by a negligent act (i.e. that of the 2nd Defendant). For chain of causation to be broken there must be a high foreseeability of the intervening act. If it is not highly foreseeable, then little chance of breaking the chain. If it is foreseeable, it is likely, if it is negligent act then more possible, and if it is reckless even more possible, and if it is a deliberate act done a 3rd party not under the control of the Defendant then it is almost inevitable.
Novus Actus Interveniens by third parties. "In general, even though A is in fault, he is not liable to B for injuries caused by C, who acts independently and with deliberate malice. A may have caused the opportunity for C to act, C is acting independently and is a new cause." There are, however, rare occasions where A may have an exceptional duty of care to B to prevent injury by C. This rarely happens. Even if A creates an occasion for C to create injury, it is independent and therefore unrelated to A. B must seek damages directly from C, and any damages for the original damage from A.
Novus Actus Interveniens by the claimant: A common sense approach using the Law Reform (Contributory Negligence) Act 1945 will be used. The courts are to use common sense when dealing with them. Negligent acts of 3rd party. Where there are multiple Defendant's, then each will be apportioned a % blame by the judge under the Civil Liability (Contribution) Act 1978. Where the Plaintiff sues one Defendant but the Defendant feels that others are also to blame, the Defendant may ask that the other Defendant's be brought into the action as co-defendant's. Where one Defendant is bankrupt, the other Defendant's must make up the shortfall, which is a bit shit for them really.
The cases to look for are: Rouse v Squires  QB 889 This involved an accident which started with one driver of a lorry, but resulted in 4 lorries crashing, the final one killing one of the drivers. The original lorry driver who caused the first crash was found jointly liable with the 4th driver who crashed, and liability (damages) apportioned between them Wright v Lodge  4 All ER 299.
This is the one with a car that had broken down. A lorry driver driving with excess speed hit the back, injuring the passenger in the car. The lorry then went across the middle of the dual carriageway, and hit other cars. The car driver was found jointly liable with the lorry driver for the car passenger, due to her not moving the broken down car, and the lorry drivers excessive speed (he got 10%), however, the car driver was found not to be liable for the lorry driver's negligent driving in causing the second car crash at the other side of the road.
It is a logical way of thinking. If two are to blame, but one more than the other, then they are both blamed, but one more than the other. It is irrelevant how many of them there are, there could be a hundred of them, the blame will be apportioned as to what their blame is, even if it is merely .0001% of the ï¿½1 billion awarded (which works out to ï¿½1 million. Imagine getting 50%, that'd be five hundred million quid!!!)
Remoteness. Should the Defendant be liable for something that is far removed from the act that he did? Not in English law. It is pretty much encapsulated by most of the above. Again, if there is remoteness from the Defendant then the court will use it's common sense. It usually goes down to foreseeability. Foreseeability: Causation is only found where the results of the negligence were "probable" or at least foreseeable - to the reasonable man he should have foreseen the end result. It used to be a "Directness" test, but this was found to be unsound law in The Wagon Mound (No. 1) The Wagon Mound (No. 1)  AC 388.
The facts of the case are rather irrelevant. However, the case decided the point of law surrounding directness in finding liability. This area of law was changed to say that what a reasonable man in the street would see as being a foreseeable or likely result of a negligent act is the one that will be held to be liable for. If one acts in a negligent way, then one may only be held to be liable for the results of this that are reasonably foreseeable. So, if one negligently drops a board into the hold of a ship, the board creates spark, this spark ignites some petrol vapour and destroys the ship, it is said by their lordships that this is so far removed from the actual negligent act that one could not find the Defendant liable.
It must be remembered: this case does NOT affect the long standing epitome that a person takes his victim as he finds him: Smith v Leech Brain & Co.  QB 405 The Plaintiff was the wife of the deceased. The deceased burnt his lip because of the negligence of the Defendant. Due to a pre-existing malignancy, this burn developed into full blown cancer, from which he died. The Court found for the Plaintiff saying that the Wagon Mound did not affect this result, because of the egg shell skull rule. The original damage WAS foreseeable; therefore the greater damage that flowed from the original damage was irrelevant, the Defendant was liable for it all. Hughes v Lord Advocate [AC] 837
A ten year old and his mate were playing near some works. A man hole cover was protected by a paraffin lamp. The boy accidentally knocked the lamp over, it fell into the hole, and caused an explosion. The Lords found that there was a known danger that the lamp could cause damage by burning because of it being negligently placed there with no other adequate protection, it was therefore no defence that it was unforeseeable that it would go on to cause an explosion in which the boy was burnt. It would seem that the policy is that if the accident was foreseeable, then it is irrelevant that the damage was greater than foreseeable or occurred in an unforeseeable way.