According to Holdsworth, it was settled in the reign of Edward III that if damage were caused to a barn by a sudden tempest, no writ of waste would lie against the tenant, even though the tenant had covenanted to restore the barn in good condition. A so-called ‘act of God’ provided a good defence to an action because the act causing the damage was not the act of the defendant.1 Lord Westbury has defined an act of God as an event caused by the forces of nature ‘which no human foresight can provide against, and of which human prudence is not bound to recognise the possibility.’2 The concept of an act of God is largely synonymous with that of novus actus interveniens3 and the phrase ‘act of God’ is still used by judges in today’s legal vernacular.4 An early text writer in the law of torts stated in 1903 that ‘the defendant can never be liable when anything out of the natural and usual course of events unexpectedly arises and operates in such a way as to make the defendant’s negligence, otherwise harmless, productive of injury.’5 Acts of God include such natural phenomena as earthquakes, cyclones, lightning, tidal waves and landslides. At common law it has been held that extraordinary acts of nature will sever the causal chain provided they are overwhelming, unpredictable and in no manner linked to the defendant’s negligence.6 An intervening natural event will be treated as a cause of the plaintiff’s loss where its occurrence was so unlikely in the circumstance that it must be considered a mere coincidence. By implication, the ordinary, as opposed to the extraordinary, operation of natural forces including weather conditions will not sever the causal chain since this must be anticipated and guarded against by the defendant. Legal responsibility is extinguished upon the occurrence of an event outside the range of ordinary experience, as human beings are only required to guard
1 W. Holdsworth A History of English Law Volume 3 (Methuen & Co. Ltd, 5th edn, 1942) 380.