Rewriting “reasonableness” in African private law: A neurodiversity perspective
South Africa’s progressive constitution requires that all law, including private law, reflect the values of dignity, equality and freedom. However, one of the most established doctrines in the law of delict, the “reasonable person” standard, has largely evaded constitutional scrutiny.
This raises a significant question: does our current understanding of reasonableness sufficiently accommodate neurodivergent persons, including autistic individuals? The answer warrants important review.
In South African law of delict, negligence is determined by asking whether a reasonable person in the position of the defendant would have foreseen the risk of harm and taken steps to prevent it. The measure is viewed as objective and impartial. However, impartiality often masks rooted social assumptions.
Historically, the “reasonable person” has reflected dominant cognitive norms; how the majority perceives risk, interprets social cues, and reacts to stimuli. These norms are implicitly neurotypical. For neurodivergent individuals, particularly those on the autism spectrum, perception and response patterns may differ in material ways. Literal interpretation of language, atypical responses to sensory overload, or difficulty reading implicit social signals can shape behaviour in ways that diverge from majoritarian expectations.
When our courts apply a neurotypical standard without proper consideration, the result may not be objective but result in structural exclusion. Accepting neurodivergence does not suggest diminished responsibility. Autism is not synonymous with incapacity. Most autistic individuals possess full legal capacity and can distinguish right from wrong. The issue is not moral blameworthiness, but whether foreseeability is assessed fairly.
South African law already recognises contextual modification of the negligence standard. For instance, children are judged against the standard of a reasonable child of similar age and professionals are measured against a competent practitioner in their field.
“These adaptations acknowledge that reasonableness is not abstract but contextual. If age and expertise justify contextualisation, cognitive profile should not be categorically excluded from principled consideration.”
Section 39(2) of the Constitution obliges courts to develop the common law in line with the spirit, purport and objects of the Bill of Rights. In Carmichele v Minister of Safety and Security, the Constitutional Court confirmed that private law cannot remain insulated from constitutional values. Where doctrine undermines dignity or equality, courts must adapt it.
Sections 9 and 10 guarantee equality and dignity. South African equality jurisprudence emphasises substantive rather than formal equality. Treating everyone identically can perpetuate disadvantage where relevant differences are ignored. In Minister of Finance v Van Heerden, the Court recognised that differentiation may be required to achieve genuine equality.
Similarly, in MEC for Education: KwaZulu-Natal v Pillay, a formally neutral rule was held discriminatory because it failed to accommodate difference. Neutrality does not shield a standard from constitutional review. A uniform neurotypical benchmark of reasonableness may similarly result in indirect discrimination if it fails to account for genuine cognitive diversity.
The United Kingdom’s Equality Act 2010 recognises autism as a disability and requires reasonable adjustments in employment and education. Canadian equality jurisprudence likewise emphasises accommodation under the Charter of Rights and Freedoms. However in these jurisdictions, negligence continues to be fixed to a neurotypical perception of reasonableness. The divide between constitutional equality commitments and private law doctrine continues. Nevertheless, South Africa’s transformative constitution arguably places it in a stronger position to challenge this conflict directly.
Improving the standard does not dismantle the negligence enquiry. It would entail reframing the inquiry: what would a reasonable person with the cognitive profile of the defendant have foreseen and done in the circumstances? This approach does not exempt or justify harmful conduct. On the contrary, it warrants that foreseeability is measured in respect of how the defendant processes risk and information. It acknowledges that cognitive difference is legitimate and supported by appropriate evidence.
Expert evidence from psychologists or neurodevelopmental specialists would aid courts in understanding how sensory processing differences or social cognition affect perception. Uncertainties regarding legal certainty are exaggerated. The reasonable person test is not rigid; rather, it is flexible, which has enabled adaptation across contexts.
South Africa’s constitutional project has already reimagined equality in relation to race, gender and culture. Cognitive diversity presents a further frontier. Revisiting reasonableness through a neurodiversity lens would align the law of delict with substantive equality not by lowering standards, but by ensuring they are genuinely fair.
The development of the common law is not optional; it is constitutionally mandated. Recognising cognitive diversity within negligence doctrine would affirm that dignity extends to how individuals think, perceive and experience the world.
