People routinely make promises about land and property without a written contract — that a child will one day inherit the family farm, or that a partner will always have a home. When the promise is broken after someone has relied on it, the law of contract often offers nothing. Proprietary estoppel is equity's answer: it protects a person who was led to believe they had or would gain an interest in property, acted to their detriment on that belief, and would suffer injustice if the owner were allowed to go back on their word. As a solicitor, you will meet this doctrine in family disputes, inheritance battles, and contests over who really owns a home.
This lesson builds the doctrine up piece by piece:
- The Doctrine and its Elements — what proprietary estoppel is, the kind of right it creates, and the core ingredients of a claim.
- Assurance — what counts as a promise about specific property, including future and implied assurances.
- Reliance and Detriment — the causal link to the assurance and the wide range of detriment that qualifies.
- Unconscionability and Formalities — the unifying principle, equitable defences, and how estoppel works around missing formalities.
- Remedies and Effect on Third Parties — how courts satisfy the equity, proportionality, and binding estates and purchasers.
- Distinction from Common Intention Constructive Trust — how the two doctrines differ and when to plead both.