In South African law of unjustified enrichment, one of the general requirements for liability is that
the defendant’s enrichment must have occurred at the expense of the plaintiff. This requirement
establishes a link between the gain of the defendant and the loss of the plaintiff, ensuring that
enrichment actions do not become mechanisms for redistributing wealth where no direct
connection exists.
The general requirement
South African courts consistently recognise four basic requirements for enrichment liability:
The defendant must be enriched;
The plaintiff must be impoverished;
The enrichment must be at the expense of the plaintiff; and
The enrichment must be unjustified (sine causa).
This formulation has been affirmed in several cases, including Theodosiou v Schindlers Attorneys
and others, where the court stated that these four elements must be satisfied before enrichment
liability can arise (Theodosiou v Schindlers Attorneys and Others 2022 (4) SA 617 (GJ)). Similarly,
the same requirements were reiterated in Aggenbach v Wessels, emphasising that they are
common to all enrichment actions despite the absence of a single general enrichment action in
South African law (Aggenbach v Wessels 2024 ZANWHC 158).
The courts have also stressed the importance of pleading and proving this element. In M.J.N v A.J.J,
the court confirmed that a claim is defective where the pleadings fail to allege enrichment,
impoverishment, or the causal connection between them (M.J.N v A.J.J 2013 (3) SA 26 (WCC)).
Meaning of “at the expense of the plaintiff”
The requirement means that there must be a causal relationship between the enrichment and the
plaintiff’s impoverishment. The defendant’s gain must correspond with the plaintiff’s loss; it is
insufficient that the defendant simply became richer while the plaintiff became poorer in unrelated
circumstances. This causal link is recognised in academic explanations of enrichment liability, which
state that enrichment must result from the plaintiff’s expense or contribution (De Vos cited in
enrichment notes).
South African authority similarly explains that enrichment liability is based on the principle that no
person’s estate should be unjustifiably increased at the expense of another, and the plaintiff bears
the burden of proving this element (MIIB Business Technologies v Matjhabeng Local Municipality
2021 ZAFSHC 233).