Equity and Trusts: Remedies, Unconscionable Conduct, Undue Influence, and Estoppel

Essential vocabulary terms and definitions covering equitable remedies, unconscionable conduct, undue influence, and estoppel based on Australian equity principles.

Unconscionable Conduct (in Equity)

An equitable doctrine that provides relief where a stronger party unconscientiously takes advantage of a weaker party who is placed in a disadvantageous position or under a special disability, focusing on the conduct of the stronger party.

Undue Influence

The improper use by an ascendant person of an ascendancy acquired over another person for their own or another's benefit, such that the acts of the subordinate person are not free and voluntary acts.

Actual Undue Influence (Class 1)

A category of undue influence where the claimant affirmatively bears the burden of proving both the existence of actual influence and the improper use of that influence by the other party to procure a transaction.

Presumed Undue Influence (Class 2)

A category of undue influence arising from a recognized or proven special relationship of influence, which shifts the burden of proof to the ascendant party to show they did not abuse their position.

Class 2A Undue Influence

A sub-category of presumed undue influence established as a matter of law based on recognised relationships of influence, including solicitor and client, doctor and patient, parent and child, guardian and ward, and spiritual adviser and devotee.

Class 2B Undue Influence

A sub-category of presumed undue influence where the relationship does not fall within an established category, but is proven on the specific facts to involve trust, confidence, and reliance or domination by the ascendant party.

Yerkey v Jones Principle

An equitable principle providing relief to a wife who guarantees her husband's business debts where the creditor relied on the husband to procure the guarantee and lacked reasonable grounds to believe the wife gave it freely and with complete understanding of the transaction.

Independent Advice (Undue Influence)

Material evidence from a qualified person that may rebut the presumption of undue influence by demonstrating that the weaker party entered into the transaction through the exercise of a free and independent will.

Laches

An equitable defence based on the maxim 'delay defeats equity', precluding a claimant from relief if there has been an unreasonable delay in initiating an action to set aside a transaction.

Estoppel by Deed

A common law form of estoppel that prevents parties to a deed from denying the facts stipulated within that deed, particularly those facts set out in its preamble.

Estoppel by Judgment

A common law estoppel precluding parties who have litigated a dispute to final judgment from subsequently denying anything decided between them in that earlier judicial proceeding.

Estoppel in Pais

A category of estoppel arising from words, conduct, or representations rather than formal court records or deeds, comprising common law estoppel, estoppel by representation, and estoppel by convention.

Estoppel by Convention

A common law estoppel based on a mutual assumption adopted by the parties as the underlying basis of their dealings, preventing either party from denying the truth of that assumption.

Promissory Estoppel

An equitable doctrine that prevents a party from going back on a promise or assurance intended to affect legal relations and acted upon by the promisee, even in the absence of consideration.

Unified Doctrine of Equitable Estoppel

The doctrine articulated in Waltons Stores v Maher subsuming proprietary and promissory estoppel into a general equitable principle grounded on preventing unconscionable conduct.

Proprietary Estoppel

An equitable estoppel preventing a landowner from strictly enforcing title rights where they actively encouraged or acquiesced in another party acting to their detriment based on a mistaken belief of holding an interest in the land.

Minimum Equity Principle

The standard in equitable estoppel where the court fashions relief that is strictly proportional to the detriment suffered, granting only the minimum intervention necessary to do justice.

Exclusive Jurisdiction of Equity

The court's equitable jurisdiction exercised to protect purely equitable rights or interests, such as trusts or obligations of confidence, where common law remedies are unavailable.

Auxiliary Jurisdiction of Equity

The court's equitable jurisdiction invoked in aid of legal or statutory rights, available only when common law damages provide an inadequate remedy.

Specific Performance

A discretionary equitable decree compelling a party to perform their contractual obligations under a binding executory contract supported by valuable consideration, typically awarded when damages are inadequate.

Doctrine of Part Performance

An equitable principle permitting enforcement of an oral contract concerning land that fails statutory writing requirements, provided the plaintiff performed acts unequivocally referable to the alleged agreement.

Prohibitory Injunction

An order of the court restraining a defendant from performing or continuing a particular act.

Mandatory Injunction

An order of the court compelling a person to carry out a positive act, either to undo or repair the consequences of a past wrong or to fulfill a contractual obligation.

Quia Timet Injunction

An injunction granted before an actual infringement has occurred to prevent an anticipated or threatened breach of rights.

Interlocutory Injunction

A provisional court order made prior to trial to preserve the status quo between the parties pending the final determination of their rights.

Negative Covenant

A contractual provision stipulating that a specific thing shall not be done, which equity may enforce by prohibitory injunction as a form of specific performance of the negative bargain.

Mareva Injunction

An interlocutory order restraining a defendant from dissipating or removing assets from the jurisdiction to ensure that any future judgment obtained by the plaintiff can be satisfied.

Anton Piller Order

An extraordinary interlocutory mandatory injunction compelling a defendant to allow a plaintiff to enter premises to inspect, copy, or seize vital evidence that is at serious risk of destruction.

Lord Cairns' Act Damages

Statutory equitable damages that may be awarded in addition to or in substitution for an injunction or specific performance in cases where the court possesses equitable jurisdiction to entertain the claim.

Account of Profits

A discretionary, non-punitive equitable remedy requiring a wrongdoer to surrender the net gain or profits derived from a breach to prevent unjust enrichment.

Equitable Compensation

A discretionary monetary remedy designed to restore an aggrieved estate or person to the position they would have occupied had the equitable breach not occurred, largely independent of common law rules of causation and remoteness.

Declaration

A conclusive, discretionary court order stating the legal rights, obligations, or status of the parties without directly ordering any coercive relief.

Constructive Trust

An equitable proprietary remedy and institution imposed by operation of law, compelling a legal owner to hold title for another because retaining full beneficial ownership would be unconscionable.

Baumgartner Constructive Trust

A constructive trust imposed when the substratum of a joint relationship or endeavour fails without attributable blame, preventing one party from unconscionably retaining pooled assets contributed for the relationship's purpose.

Rule in Keech v Sandford

An equitable rule creating an irrebuttable presumption that a trustee who renews a trust lease in their personal capacity has breached their fiduciary duty, holding the renewed lease on constructive trust for the beneficiaries.