Equitable estoppel gives rise to a distinctive and controversial form of liability, which arises where one person (the inducing party) leads another (the relying party) to believe that the inducing party will act in a particular way in the future, and the relying party acts on that assumption to his or her detriment. Liability of this kind has a respectably long history in English law, but has cycled through a number of expansionary and contractionary movements. This paper explores the basis of this category of liability, sketches its cyclical movements, and advances an explanation as to why views differ so sharply as to whether it should exist. The principle appears to occupy an uneasy and insecure place on the edge of the law of obligations, suggesting that it lies at the limits of what people are, as a matter of legal obligation, entitled to expect from one another.
Robertson, Andrew, Revolutions and Counterrevolutions in Equitable Estoppel (April 19, 2017). S Worthington, A Robertson and G Virgo (eds), Revolution and Evolution in Private Law, Oxford, Hart Publishing, 2018, 161–175.