Before answering the questions of causality, it is therefore first necessary to determine the scope of the respective rule of law. The third and last of these unified notions of causality is physicalist in its ambitions. Some theorists have thought that we can say more about the nature of the causal relationship than about the fact that it is scalar, and that a considerable amount of it is necessary for responsibility. In this third perspective, the nature of causality is found in the mechanistic concepts of physics: matter in motion, energy, force (Beale 1895, 1920; Epstein, 1973). This test is similar to the view of the substantial factor in its conception of the causal relationship as scalar, but differs in its reductionist ambitions: causality is not primitive, but can be reduced to some kind of physical process. Second, even if we limit ourselves to the law of a legal tradition, there will be distinct areas of law within that tradition that will use causality in their rules of liability, such as contracts, torts, property, constitutional law, and criminal law in the Anglo-American legal tradition. Arguably, the exact contours (and perhaps even the central concept) of causality differ between these domains; For example, it is plausible to believe that there is a significant difference between the concept of contract law of consequential damages resulting from a breach and the concept of direct causation in criminal law required to detect a completed criminal offence (Moore 2009a: Appendix). Therefore, in order to ignore any differences between areas of law, this article focuses on what members of the Anglo-American legal tradition consider to be the predominant use of causality in law, which is attributing responsibility to actors who cause harm to others. The areas of law in which such a causal transfer of liability predominates are criminal law and tort. The entry therefore focuses on these two areas of law, as they are central to the use of causality in the Anglo-American legal system (and probably for any system). These are also the areas of law where causality has been (by far) the most taken into account in law and legal theory. The problems posed by conventional legal analysis of causality—in the sense of a range from cause to fact and immediate causality—have led some legal theorists to abandon the bifurcation of causality in law and seek a unified concept of causality that is far more discriminatory (in what it admits as cause) than the counterfactual test of cause has made the conventional analysis hopelessly promiscuous. Indeed, one seeks a unified concept of causality that is so discriminatory that it can do the work done in the conventional analysis of causal doctrines of cause and immediate cause.

It is far from clear that causation is in fact a sufficiently discriminatory relationship that it can do as much work in assigning responsibility. Nevertheless, there are three such propositions in the legal literature, each with some doctrinal support in law. This issue does not infect as prominently the following two policy-based tests on proximate cause, predictability, and harm-to-risk testing. For these tests attempt to describe a real fact that plausibly determines moral culpability and associates a defendant`s guilt with certain damages. These criteria therefore serve the kind of policy that the concept of causation is intended to serve in justice-oriented theories of criminal law and tort. Their novelty lies in their change in how and where legal causality determines fault. According to these theories, the “legal cause” is not a refinement of an accepted desert determinant, true causality; Rather, it is a refinement of another guilty and desert-defining state of mind. Since Hume`s analysis takes “the glue” out of the causal context – a cause does not allow its effect to occur, it only regularly follows its effect – it is generally classified as skeptical. And in a sense, it`s when you deal with the “glue” that is essential to any relationship that is properly called “causal.” But Hume`s views are not radical enough to be considered skeptical in the sense of legal theorists. For Hume gives what Saul Kripke calls a “skeptical solution” to the problem of causality (1982: 66-68): Hume does not deny that causality exists, but reduces it to something less ontologically queer than “glue.” The fourth group of problems with the counterfactual criterion relates to the sub-inclusive character of the test, which, in well-known cases of overdetermination, generally appears in legal theory. These are cases where each of the two events, c1 and c2, is independently sufficient for a third event e.

Logically, the sufficiency of c1 and c2 means that neither c1 nor c2 are individually necessary for e, and therefore, in the counterfactual analysis of causality, none of them can be the cause of e. The law uniformly rejects this conclusion (although some philosophers such as David Lewis have asserted uncertainty about causality in such cases in their own intuitions), so such cases pose a real problem for counterfactual analysis of causality in law.