By far one of the best decisions I’ve made in my life is choosing to read Law at university. I understand there is a tendency for people to think that their interests or professions are somehow relevant to other topics, but I genuinely think that law can help people stop talking past each other. Tort law is essentially about bringing claims against people for committing wrongs; it is the civil version of criminal law.
Causation
By far the most I’ve written about on this blog has been about the causes of terrorism (and this should be last post on it in a very long time) – but everyone seems to miss the definition of what causation means. Fortunately, the English and common law courts have spent centuries talking about what constitutes a cause – and I think they’ve got it right. If you bring a claim against someone in the tort of negligence (for example), you need to establish not only that there was a breach of duty (of acting in a non-negligent way) but also that the breach of duty caused the loss you suffered. The general test has been stated many times but here is a recent restatement from Lord Phillips in Sienkiewicz v Greif [2011] UKSC 10 at [16]
It is a basic principle of the law of tort that the claimant will only have a cause of action if he can prove, on balance of probabilities, that the defendant's tortious conduct caused the damage in respect of which compensation is claimed. He must show that, but for the defendant's tortious conduct he would not have suffered the damage.
However, but for causation is not appropriate as the only test: but for the parents of the tortfeasor having sex and conceiving said tortfeasor, the tort would not have occurred. Of course we would not say in any real sense that the parents had caused the tort to occur. A lot of people seem to think this is an absurd example, so I’ll give another: a negligent driver speeds until he gets to a roundabout. He is then struck by lightning; but for speeding, he would not have been at the junction. This, again, is clearly not causally relevant. Hence, the law superimposes a test that where there is an informed, deliberate and free act, the chain of causation is broken (per Goff LJ in R v Pagget (1983) 76 Cr. App. R. 279 at 289). There are many cases which show this principle in action, so I’ll only give a few of my favourite criminal cases.
R v Pagget: the defendant had taken his ex-girlfriend hostage using a shotgun. The police were called to the scene where they were threatened and fired upon. In the ensuing gun fight, triggered by the defendant, the police shot the ex. It was held that the police were not responsible for the death of the hostage because their action was not free.
Saunders v Archer (1575) 75 E.R. 706: the defendant was a husband and a father who poisoned an apple in the hopes that his wife would eat it and die. The wife, without knowledge of the poisoning, gave the apple to their daughter who died. It was held that the husband was responsible for the death of the child because but for his act, the child would not have died. The wife’s act was not a break in the chain of causation because it was not informed action.
The reason English law does this is because it values individualism and responsibility for one’s actions. To suggest that someone else is responsible for an act you authored (i.e., you did it freely, deliberately and being informed), is to significantly undermine free will and sense of control over one’s life.  Professor Simester (Legal Theory, 1995) has explained this far better than I can hope to:
... if we so weaken the relationship between the consequence [of an act] and its author by indiscriminately sharing responsibility for the authorship of each consequence that sense of our individuality as people in a specific relationship to the world is much diluted
Simester is saying, in essence, we express our autonomous lives by being connected with the choices that we make. By separating out the connection between consequences and authorship (either by holding me responsible for acts I have not authored or not holding me responsible for acts I have committed), the ‘connection’ that makes real autonomy and individual responsibility is gone. Hence, free, informed and deliberate actions should be held to be the work of only the individual involved.  
Causation applied
So why is all of this relevant? Because pundits who have spent so much time talking about ‘causes’ do not have the wisdom of their Lordships in these cases. From Glenn Greenwald’s latest column:
if Person X walks up to Person Y on the street and spits in his face, and Person Y then pulls out a gun and shoots Person X in the head and kills him in retaliation, one can observe that Person X's spitting was a causal factor in Person Y's behavior without remotely justifying Person Y's lethal violence.
This is not the position English law takes and neither should it be the position of rational people. Lets ignore that Greenwald is attempting to apply this analogy to terrorism (this is wrong for three reasons I have already gone through), and just focus on the example given. Is Person Y’s action a free, informed and deliberate response? Yes, it is. Causation is not simply about ‘but for’ or ‘and then...’ And the fact that this individual has authored an action means he is the cause of his action. It is no use talking of ‘provocation’ because we do not allow provocations to vitiate causation (thankfully, since the Coroners and Justice Act (2009)).
Again, to make it painfully obvious that this is the right approach, consider an individual who is murdered after her partner finds out that she was having an affair. The action was free, informed and deliberate. Thankfully, like terrorism, it is not a course of action that people usually take (and thus reinforces the idea that these actions are not caused by anything other than by the individual). That this is the case was put poignantly by the Supreme Court of Alaska Hurn v Greenway 293 P.3d 480 (2013) (h/t The Volokh Conspiracy). Here are the facts of the case:
Simone Greenway and her friend Carrie Randall–Evans were dancing together in a suggestive manner and teasing Jeffrey Evans, Carrie’s husband, when Jeffrey left the room, returned with a pistol, and shot everyone inside, killing Carrie. He then shot and killed himself. David Hurn, the father of Carrie’s two minor children, sued, claiming that Greenway’s participation in the dance was negligent either because it breached her duty as homeowner to control her guests or because it created a foreseeable and unreasonable risk of violence.
But for the suggestive dancing, in this specific case, the murders of all the individuals would not have occurred. Does that mean the dancing caused the murder? The Supreme Court of Alaska held
We reject the idea that victims are responsible for the violence they endure in the home, and we will not blame them for their otherwise reasonable actions simply because those actions foreseeably result in violence.
The same applies to racists and terrorists; sure, a racists’ worldview means that but for the presence of the black person, he would not have assaulted him, but his action was free, informed and deliberate and he is the cause of that action. For the terrorist, granting that but for Western foreign policy he would not have acted that way (which I don’t grant), it is still not a cause of his actions. And unless we want to go around saying that the colours of people’s skin, the choices people make about their sex lives, the dances they happen to take part in are causes, we should resist Greenwald’s wide definition of causation.
And what if we dilute the claim that Greenwald makes – namely, that we should still listen to the racists and terrorists so we know the reasons they give for their actions? Absolutely not: it is irrelevant (and insulting) to start talking about the role of a battered woman, the role of a victimised minority or our foreign policy because it ignores that the action was caused by the defendant’s own action. Talk about the worldview that these people accept because, to arrogantly quote myself, ‘to be within the grounds of recruitment requires an aversion (or openness to an aversion) to a free society of consent’ – and as the empirical evidence shows, it has nothing to do with the reasons pundits like Greenwald give.
Responsibility for third parties
There is another reason why causation is important; it also explains why, when human shields are used, there is no responsibility attached to Western forces. But for the terrorists’ use of a certain area, it would not have been targeted (assuming, for now, the action is proportionate). It is unconvincing to argue that there was a free, informed and deliberate action because the situation matches R v Pagget. The IDF, acting in self-defence, targets an area from which a threat emerges and if it kills civilians, the responsibility should like solely with Hamas. Of course, states should take the presence of civilians into account when working out what is ‘proportionate’ (in the same way that the police in Pagget should not have used a rocket launcher to target the defendant) – but where they act proportionately, their action is not free. I am not going to spend the rest of this post explaining whether this was or was not the case in Israeli counter-terrorism operations because I merely want to justify the principles I’m talking about.
Perhaps one of the most perverse responses I’ve heard to statistics about coalition forces being responsible for a tiny minority of civilian deaths is that the insurgents and terrorists who cause the overwhelming majority of deaths would not have happened but for the Western invasion. The argument is essentially saying that ‘you unleashed the forces.’ That this is wrong should be clear (empirically, it is wrong to say that it was cause; normatively, it is wrong to blame actions authored by someone on an individual). But there are further cases which help elucidate why such a view is incorrect.

Lord Hope made clear in Mitchell v Glasgow City Council [2009] UKHL 11 at [15] that ‘the law does not impose a duty to prevent a person from being harmed by the criminal act of a third party based simply upon foreseeability.’ Accepting that it was foreseeable that people would be attacked is not enough to impose an obligation (this is partly for reasons give above about personal responsibility). Hence, in Hill v Chief Constable of West Yorkshire, there was no ‘general duty of care owed by the police to members of the public at large to apprehend an unknown criminal.’ The coalition forces in Iraq could have been responsible for the actions of third parties if they had control of them and negligently let them go. But because they did not, no duty let alone causation can be applied if we are to respect personal responsibility.