Supervening impossibility of performance – A conceptual conundrum and restatement of principles

• Citation: (2022) 33 Stell LR 605
• DOI: https://doi.org/10.47348/SLR/2022/i4a2
• Published date: 28 March 2023
• Pages: 605-617
• Author: du Plessis, J.
• Date: 28 March 2023

605

https://doi.org /10.47348/ SLR/2 022/i4 a2

SUPERVENING IMPOSSIBILITY OF

PERFORMANCE – A CONCEPTUAL

CONUNDRUM AND RESTATEMENT OF

PRINCIPLES

Jacques du Plessis

BComm LLB LLM PhD

Distinguished Professor, Stellenbosch University*

Abstract

In dening supervening impossibility of performance, the South African

law of contract recognises a “general rule”, which entails that performance

is excused if impossibility is brought about by vis major or casus fortuitus.

This rule is then made subject to a vague and broad list of qualications. It is

argued here that this approach is unhelpful, and that the general principles on

supervening impossibility of performance may be restated in more concrete

terms. The general rule may simply maintain that absolute impossibility excuses

a debtor. The rule should then be subject to clear and specic qualications.

These qualications entail that liability may nonetheless be imposed if: (i) the

debtor actually foresaw or reasonably should have foreseen the event giving

rise to impossibility; (ii) the debtor could have taken reasonable steps to

avoid such an event or overcome its consequences; (iii) the debtor created

the impossibility; or (iv) the debtor was in mora at the time of impossibility. It

is argued that it may be unhelpful to include fault on the side of the debtor in

this list, inasmuch as fault could actually obscure other qualications to the

general rule, rather than act as a qualication in its own right.

Keyword s: Supervening impossibility of performance; vi s major; force

majeure; casus fortuitus; termination of co ntractual liability

1 Introduction

Parties to a contract normally expect that liability would terminate due to

performance. However, there are some exceptional grounds for releasing a

party from liability in the absence of performance. Supervening impossibility

of performance,1 which recently has been particularly prominent due to the

* I am gratef ul for the comments of my col league Gerhard Lu bbe and the anonymou s referees

1 See Nuc lear Fuels Corporation of SA ( Pty) Ltd v Orda AG 1996 4 SA 1190 (A) 1200 1203; Orda AG

v Nuclear Fuels Co rporation of S A (Pty) Ltd 1994 4 SA 26 (W) 72; M V Snow Crystal: Trans net Ltd

t/a National Port s Authority v Owner of M V Snow Crystal 2008 4 SA 111 (SCA) para 28 The concept

“superven ing” impossibi lity is an import from Eng lish law into South Africa n law (see eg Stillwell v

Kama 1916 EDL 319 322), bu t the locus classicus of Pet ers Flamman and C o v Kokstad Munici pality 1919

AD 427 unequivoc ally held that our r ules derive fr om the civil law, and rejec ted earlier at tempts to impo rt

a common-law app roach, which relied o n “implied term s” to determin e whether liabilit y had termi nated

(2022) 33 Stell LR 605

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