The parol evidence rule: A South African perspective
The authors of one of the standard South African texts on the law of evidence, Hoffman & Zeffert, say the “the parol evidence rule . . . shares with the Holy Roman Empire the distinction of being misleading in all three of its component parts.” The Holy Roman Empire wasn’t holy, Roman or an empire to really speak of.
The parol evidence rule was received into South African law through English law. This was largely as a result of judicial influence, as most of the country’s best judges in the early years of the (then) Union of South Africa (and even before) which was established in 1910, were educated in England. The result was that they incorporated particular mechanisms from English law and grafted them onto the Roman-Dutch principles of the law of South Africa as it was at the time. But to return to the three component parts of the rule in South African law:
1. Two rules, not one
The parol evidence rule has application in instances where parties to an agreement (contract), elect to reduce the terms of their agreement to writing. For this reason, the parol evidence rule is not a single rule, but effectively two rules, the first dealing with whether the document containing the terms of the agreement is in fact the complete agreement (i.e. whether the document contains a “full integration” of the consensus that gave rise to agreement), while the second relates to the question to which extent proof of facts extraneous to the integration (=document) may have some effect on the interpretation or meaning of the terms evidenced by the integration.
2. Not a rule of evidence, but rather substantive law
The two constituent parts of the parol evidence rule actually are not rules of evidence, but rules relating to the substantive law in respect of agreements reduced to writing.
3. What the rule deals with
While the “rule” purports to relate to oral (“parol”) evidence, it is misleading, as it also relates to any other kind of evidence that may pertain to the construction placed on the integration of the agreement between the parties, such as documents, e.g. letters purporting to be proof of negotiations leading up to the agreement, or even real evidence such as recordings or photographs etc.
What the rule provides
Once is has been established that an agreement was reached which the parties embodied in a document or other form of writing (perhaps even an electronic version), the question arises as to whether the writing represents fully all the terms of the agreement. In the absence of proof that the parties intended that the writing would represent only a part of the agreement reached between them, our courts deem the integration to represent the full and complete version of the agreement. The parol evidence rule now precludes any party to the agreement from adducing evidence at trial that seeks to either disprove any term or terms of the agreement, or seeks to vary any of the terms in the agreement.
The rationale behind the rule is simply one that holds a party to a contract to his or her bargain, prohibiting any party from later attempting to vary the agreement or to attempt to prove the agreement to have been made on terms meaning something else than what appears on the face of it from the document. For that reason: Caveat subscriptor.
(Note: This does not pretend to be a complete and comprehensive explanation of the parol evidence rule as it functions in South African law. It is only a very brief summary.)