By Sara Joy - Law Student @ Downing College, Cambridge
Content warning: discussion of suicide in a legal context
A novus actus interveniens is an intervening act which can break the chain of causation, relieving the first actor of responsibility. In criminal law, this means that if a defendant stabbed the victim and they died, for example, provided a novus actus occurred in between, the defendant may be absolved of criminal liability in regards to murder.
The courts approach to determining whether an action constitutes as novus actus interveniens typically follows the formula suggested by Hart and Honoré and later applied in Kennedy No.2  by which a supervening action must be “free, deliberate and informed (FDI)” to break the chain of causation. The courts are therefore willing to accept the novus actus as the second actor’s assertion of autonomy, a principle which is deeply valued in British law, which can absolve the first actor of responsibility for any consequence that occurs. This view was formalised in the judgement of Kennedy No.2 : “informed adults of sound mind are treated as autonomous beings able to make their own decision how they act”.
This case set a precedent requiring the second actor to be independent and not be acting in concert with the first actor. R. v. Hughes  imposed an additional requirement for the second actor to have intended to cause the result or perhaps be at least prepared to take a substantial risk of causing it. In Smith and Hogan’s Criminal Law, it is also claimed that a defendant will not be liable for a third party’s intervening act if “was not reasonably foreseeable”, this principle is confirmed by judges’ directions on foreseeability to the juries in R. v. Wallace  and R. v. Roberts .
Although, the English traditionally legal system seemingly adopts Hart and Honoré’s approach by the use of the “FDI” formula, it seems that this approach is lacking in the context of reactive suicides specifically. There is a moral dilemma with absolving the perpetrator of a violent offence of guilt if a victim’s suicide appears to be voluntary and free due to the fact the suicide is still inherently reactive in nature and so, ‘caused’ by the defendant’s actions. Thus, the philosopher Feinburg’s approach is perhaps more desirable. Feinburg states that “if [B]’s action is triggered by [A]’s and especially if it is caused to happen by [A]’s intentional triggering, how can it possibly be said without qualification to be [B]’s own action, a free, informed, deliberate, that is ‘fully voluntary’ act?”.
This is the case for reactive suicides, that is, a suicide that would not have occurred ‘but for’ the defendant’s initial actions. Can this suicide truly be regarded as “free, deliberate and informed” act? When considering if this is possible, it is important to reflect on several factors, a significant factor being the timeframe between the defendant’s initial actions to the victim’s suicide. Generally, there is a principle that any immediate reaction by the victim to a situation created by the defendant can be attributed to the defendant so long as it is not “daft” or reasonably unforeseeable as stated in the judgment of R. v. Roberts . In this case, the victim jumped out of a moving car to escape the sexual advances instigated by the defendant and sustained actual bodily harm. The defendant was convicted as the jury felt it was not so “daft” or unexpected that no reasonable man would have acted in the same way.
To conclude, the application of novus actus in English law remains highly context specific. As a result, there can appear to be some logical fallacies in the application of this principle in various cases. From a moral perspective, whether the current usage of the “FDI” formula extends far enough or whether juries should be directed more in line with Feinburg’s philosophy.
Any of the cases mentioned but Rebelo  EWCA Crim 306 is an interesting one to look at.
Influential article on Novus Actus (Glanville Willaims): https://www.cambridge.org/core/services/aop-cambridge-core/content/view/0060BE472C86F753C38BE1518779AAEA/S0008197300109717a.pdf/finis-for-novus-actus.pdf
Novus actus in the context of tort law (Sewell & Kettle): https://sklawyers.com.au/dictionary/novus-actus-interveniens/