Abstract
This study explores the evolving dynamics between the Bill of Rights and the admission of extrinsic evidence within the context of South African contract law. It scrutinises the conflict between the established formalist principles (particularly the parol evidence rule) and the transformative demands of constitutional interpretation. The study highlights how rules of evidence, which were once strictly applied to maintain legal certainty are now being re-evaluated in light of the constitutional values such as equality, fairness and dignity By use of doctrinal analysis and theoretical framing, the study further demonstrates that the exclusion of extrinsic evidence can compromise the constitutional mandate to develop the common law in alignment with the spirit, purport and object of the Bill of Rights. It advocates a more flexible, value-driven approach to contract interpretation, one that acknowledges the horizontal application of constitutional rights and the need to balance the written text with substantive justice. The notion of constitutional contextualism is advanced as a framework for reconciling competing demands. Ultimately, the study asserts that extrinsic evidence should not be viewed as a threat to contractual certainty, but rather as an essential tool for courts to fulfil their constitutional obligations and promote fairness in private law relationships.