Equitable Estoppel in New Zealand: One Overarching Doctrine and its Limitations

The courts in New Zealand are clear that equitable estoppel is one unified doctrine “based on the concept of unconscionability”. This unified doctrine has replaced the traditional types of equitable estoppel, such as promissory and proprietary estoppel, as well as estoppel by convention and probably even common law estoppel. This article will chart the rise of a unified estoppel in New Zealand and then critically examine some of its features that might cause us to question the utility of a broad-based doctrine. What is the meaning and role of detrimental reliance by the defendant? What does the notion of unconscionability mean and can the term sensibly provide the underlying basis for estoppel? What are the remedies that a successful estoppel claim is meant to achieve? Finally, the article will provide some suggestions for the future application of the unified doctrine of estoppel by the New Zealand courts.