Res ipsa loquitur as a legal maxim in motor vehicle accidents

March 1st, 2024

Litigation emanating from motor vehicle accidents are common in South African courts. Be it claims for damages, claims based on personal injuries, or matters appearing in our criminal courts. This is not surprising, considering that South Africa has approximately 750 000 km of roads and is estimated to have the tenth largest road network in the world. This is further exasperated by the growing deterioration of our roads and the (currently more than) 11 726 476 registered number of vehicles on the roads (Road Traffic Management Corporation ‘State of Road Safety in South Africa: January 2021 to December 2021’ (, accessed 1-2-2024)).

Due to the fact that direct evidence is sometimes lacking in these cases, be it due to no eyewitnesses being available, an accused electing not to testify, or just totally unreliable evidence presented, it behoves litigants and presiding officers alike to take cognisance of the legal maxim of res ipsa loquitur (literally meaning the thing speaks for itself) which is often used in negligent driving cases. This maxim is one type of circumstantial evidence, which assists the prosecution/plaintiff in criminal or civil proceedings in proving negligence. The gist of the maxim is in essence that, ‘if a motor vehicle accident happens in a manner which is unexplained, but which does not ordinarily occur … the court is entitled to infer that it was caused by negligence’ (S v Mudoti 1986 (4) SA 278 (ZS)). This inference is based on ‘the totality of the circumstances and the shared knowledge that arises out of human experience’ (FindLaw ‘Res Ipsa Loquitur and Evidence Law’, accessed 1-2-2024). It is important to note that this is an inference that can be drawn, and not a presumption of law (Arthur v Bezuidenhout and Mieny 1962 (2) SA 566 (A) at 574E. See Pat van den Heever and Natalie Lawrenson ‘Inference of negligence – is it time to jettison the maxim res ipsa loquitur?’ 2015 (July) DR 32). This inference is only permissible while the cause of the accident remains unknown. The court leans on common knowledge that such events normally only happen if someone was negligent. This inference can, of course, be rebutted by the defendant/accused by proffering an explanation on how the incident occurred. In the matter of Arthur the judge eloquently enunciated the position to be that ‘once the plaintiff proves the occurrence giving rise to the inference of negligence on the part of the defendant, the latter must adduce evidence to the contrary.’ The word ‘must’ in this context to read that the defendant ‘must tell the remainder of the story, or take the risk of judgment being given against him’ (Arthur at 574). This does not, however, mean that the onus shifted. The onus of proof at all times still firmly lies with the state/plaintiff. If such an explanation is indeed proffered by the defendant/accused, the court will still test this explanation by considering the probability and credibility thereof, and ultimately at the end of the case, whether the state/plaintiff has discharged the onus of proof resting on them as the court would do in any other case of negligence that would be brought before it (Sardi and Others v Standard and General Insurance Co Ltd 1977 (3) SA 776 (A)).

Though the maxim might sound simple enough to apply, from the case law it is apparent it can be more complex than it would seem at first glance. On the careful reading of the relevant case law pertaining to the use of the maxim, it is clear that it has no general application to highway collisions (MacLeod v Rens 1997 (3) SA 1039 (E)). It is not self-evident that merely because two vehicles collided with each other, or in general an accident occurs, the person in control of one or other of them must have been negligent. A different class of occurrence is to be found, and therefore, for the maxim to be brought into play the occurrence should sufficiently be described to make the finding of negligence self-evident from its very nature. It is axiomatic that for the maxim to come into play the ‘instrumentality’ must be within the exclusive control of the defendant/accused, and the occurrence must be of such a nature that it does not ordinarily happen unless someone was negligent (University of Pretoria (UP) ‘The application of the doctrine of res ipsa loquitur to medical negligence cases in South Africa’ (, accessed 1-2-2024)). ‘Even then, the inference need not be drawn, and, further, it may be negatived by a contrary explanation by the defendant or by some other means’ (Road Accident Fund v Mehlomakulu 2009 (5) SA 390 (E)). It is also clear that this explanation must, at least, be more than a mere theory, conjecture or hypothetical suggestion and be based on fact.

To illustrate the practical use of the maxim, Rumpff JA articulated ‘the example of a motor vehicle driving from its correct side of the road onto its incorrect side of the road and causing damage or injury as a result thereof’ (UP (op cit) at 19). In the absence of an explanation, this would be indicative of the driver of the vehicle being negligent. ‘Thus, the mere evidence of the detrimental occurrence and the fact that it was caused by an object under the exclusive control of the defendant constitutes a prima facie factual inference that the defendant has been negligent’ (UP (op cit) at 20).

Simply stated, what this approach effectively does, using the technique of inferential reasoning, is to establish that ‘generally a roadworthy motor vehicle under the control of a reasonably skilful and careful driver will behave in a manner consonant with the basic traffic rules designed to ensure the safety of all users of the road’ and will not deviate from its path of travel into the line of travel of another road user (MacLeod at 1047I-J). It is, however, important to note the mere implementation of this approach oversimplifies the use and ambit of the maxim. For the maxim to effectively come into play the occurrence should be described sufficiently to make the finding of negligence self-evident from its very nature, and even then, the inference need not be drawn or may even be negatived by a contrary explanation by the accused/defendant (Mehlomakulu at para 9). ‘Not every occurrence that justifies an inference of negligence … justifies a finding of res ipsa loquitur’ (UP (op cit) at 19). The mere fact that a vehicle is involved in a collision is not on its own enough to bring the inferential reasoning or res ipsa loquitur into play. That alone is not enough to require the driver to tell the rest of the story and give an explanation of the collision inconsistent with negligence in order to avoid an inference of negligence being drawn. Thus, for the maxim to apply the only known facts relating to negligence must be the occurrence of the collision which presupposes that sufficient detail is known of the collision to warrant the inference (Berriman v RAF [2005] JOL 14225 (E)). Simply stated, the maxim does not apply unless it is necessary to consider solely the incident without the aid of any other explanatory evidence.


In conclusion it should thus be clear that the maxim is ‘no magic formula’ which permits a court to simply ignore the deficiencies in the state/plaintiff’s evidence and to take a so-called short cut straight to a conclusion of negligence (Arthur at 573). By doing this courts can be tempted into speculation or conjecture.

As Van den Heever and Lawrenson (op cit) at 34 conclude: ‘Lawyers are often accused of using Latin tags to befuddle the public and demonstrates that the law is far too difficult to be left to mere laymen. Some Latin phrases, seem to befuddle the lawyers themselves. Res ipsa loquitur is a case in point’ (see P van den Heever and P Carstens Res Ipsa Loquitur & Medical Negligence: A Comparative Survey (Cape Town: Juta 2011) at 183).

Vaughn Shone BProc (UFS) LLB (UNISA) is an Acting Magistrate in Oudtshoorn.

This article was first published in De Rebus in 2024 (March) DR 15.