Proprietary estoppel

Proprietary estoppel is a legal claim, especially connected to English land law, which may arise in relation to rights to use the property of the owner, and may even be effective in connection with disputed transfers of ownership. Proprietary estoppel transfers rights if,

If these elements of assurance, reliance and detriment, and unconscionability are present, the usual remedy will be that the property will be transferred to the claimant, if the court views the reliance to warrant a claim in all the circumstances.

In 1862, in Dillwyn v Llwellyn, a son was held to have acquired a house from his father because he was given a written notice that he would, despite never having completed a deed for conveyance, after the son spent time and money improving the property. In Willmott v Barber Fry J considered that five elements had to be established before proprietary estoppel could operate:

These elements were, however, refined by future case law over the later 20th century and in the early 21st century. Indeed, the High Court in Waltons Stores (Interstate) Ltd v Maher, recognised that both the principles of proprietary and promissory estoppel encompass the broader principle of equitable estoppel.

Proprietary estoppel is one of four principal mechanisms to acquire rights over property, seen particularly in the case of land (the others being a contract, an implied trust, and adverse possession). Unlike a contract or gift, which depend on consent, or resulting and constructive trusts that depend primarily on the fact of contribution, a proprietary estoppel arises when a person has been given a clear assurance, it was reasonable of them to rely on the assurance, and they have acted to their detriment. This threefold pattern of proprietary estoppel (clear assurance, reasonable reliance and substantial detriment) makes it consistent with its partner in the law of obligations, "promissory estoppel".

Although English law has not yet recognised promissory estoppel as giving rise to a cause of action, (as has been done under the American Restatement (Second) of Contracts §90 and by the Australian High Court in Waltons Stores (Interstate) Ltd v Maher) in Cobbe v Yeoman's Row Management Ltd Lord Scott remarked that proprietary estoppel should be seen as a sub-species of promissory estoppel. In all cases it allows people who act on others' assurances about legal rights, even without them attaining express agreement. For example, in Crabb v Arun DC a farmer acquired the right to a path over the council's land, because they had assured him that if he sold off one portion an access point would remain. In all cases, the minimum pattern of an assurance, reliance and some form of detriment is present.

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