Legal causation can be distinguished from factual causation. Factual causation can be described as answering the question of whether the conduct of a wrongdoer caused the harm suffered by the plaintiff. The test for factual causation is found in the phrase “sine qua non” meaning “but for the conduct” the harm would not have been there.
In Lee v Minister of Correctional Services, the Court had to determine liability when the Plaintiff contracted TB while he was held at Pollsmoor Prison. The Court determined that the prison was negligent in its policies to minimise the transfer of the disease between inmates. Despite the Prison’s negligence, it could not be held that it was liable for the specific case of transfer of the virus as the exact origin and moment of transfer of the virus could not be determined.
In terms of Legal causation, the courts have held that the test for legal causation is more flexible, the extent of liability attributed to the wrongdoer must be established and the test of “reasonable foreseeability” can be applied to answer the question.
The talem qualem rule is used in what is sometimes referred to as “thin skull” cases. It arises when a plaintiff has some underlying weakness (physical, psychological, or financial) that causes a plaintiff more serious injury or loss because of the defendant’s conduct than what would have been the case if the underlying weakness was not there. The Defendant is usually ignorant of the fact that the Plaintiff has a defect or weakness until such defect causes more harm or injury.
In essence, the rule means that a “wrongdoer” must take the victim as he finds him. The question is whether the wrongdoer should be held liable for the harm that was aggravated by the existence of the weakness and could the consequences have been foreseen by the wrongdoer.
In Gibson v Berkowits the plaintiff sued the defendant for pain and suffering and loss after a procedure that caused her further treatments and ongoing medical treatment, as well as short-term pain and dysfunction. As a result of the pain and dysfunction, the Plaintiff experienced a loss of interest in her physical appearance which resulted in her being demoted at work, and she developed a severe depressive disorder. The Court found that her depressive condition was justifiably linked to the defendant’s negligence and that her predisposition to depression and ability to deal with trauma was a good example of a “thin skull” case. The Court held that psychological sequelae following physical injury are reasonably foreseeable and that the wrongdoer can be held liable for the psychological injury even though it is further removed from the negligent conduct.
Financial “thin skull” is illustrated in the case of Smit v Abrahams where the Plaintiff claimed the cost of the rental of a replacement vehicle after his vehicle was damaged and he could not afford the repairs. The Court investigated the rule and concluded that the fact that the plaintiff has an “egg-skull” is just one of the factors that must be considered when applying the flexible test for causality and that all the circumstances should be considered in terms of fairness, reasonableness, and justice before the damage is imputed to the wrongdoer.
 Dutton I, The Practitioners Guide to Medical Malpractice in South African Law. 2015 (Cape town)
 2013(2) SA 144 CC
 1996 (4) SA 1029 (W)
 1994(4) SA 1 (A)
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