Equity and the common law

Equity emerged as a supplementary jurisdiction to remedy the rigidity of medieval common law, developing into a distinct body of principles and remedies administered separately until the Judicature Acts 1873-1875 fused their administration—but not their substance. The fundamental rule remains that where common law and equity conflict, equity prevails (Earl of Oxford's Case, now s.49 Senior Courts Act 1981). Equity operates through maxims reflecting its concern with conscience and fairness: it acts in personam, follows the law, requires clean hands, and treats as done what ought to be done. Though procedurally unified since 1875, equity retains distinct doctrines (trusts, fiduciary duties, proprietary estoppel), remedies (specific performance, injunctions, rescission), and its characteristic discretionary approach—creating what Ashburner famously described as 'two streams of jurisdiction' that 'run in the same channel' but 'do not mingle their waters.'

Earl of Oxford's Case (1615) 1 Ch Rep 1: Established that equity prevails over common law in cases of conflict when Chancery granted an injunction restraining enforcement of a common law judgment obtained by fraud. This principle underpins the entire equity jurisdiction.

Walsh v Lonsdale (1882) 21 Ch D 9: Agreement for lease created same rights in equity as if formally granted, demonstrating the maxim 'equity treats as done what ought to be done.' Critical for understanding how equity gives effect to parties' intentions despite incomplete formalities.

United Scientific Holdings Ltd v Burnley BC [1978] AC 904: Lord Diplock warned against the 'fusion fallacy' while paradoxically suggesting substantive fusion had occurred. The case remains the touchstone for debates about whether the Judicature Acts merged substance or merely procedure.

Tinsley v Milligan [1994] 1 AC 340: Party to illegal transaction could enforce resulting trust without pleading illegality, so 'clean hands' maxim didn't bar relief. Shows how equitable maxims operate as flexible principles rather than absolute rules.

AIB Group v Mark Redler [2014] UKSC 58: Distinguished 'traditional' breach of trust (strict liability, restitutionary) from breach causing loss (compensation-based, requires causation). Demonstrates continuing substantive differences between equitable and common law approaches to liability.

Courts first determine whether the claim engages equity (trusts, fiduciary relationships, equitable remedies) or common law. If equity applies, they assess whether equitable intervention is warranted: Is the common law remedy inadequate? Has the claimant acted unconscionably? For remedies, courts apply structured discretion—specific performance requires damages to be inadequate (typically land sales), injunctions need a serious issue and balance of convenience. Equitable defences (laches, acquiescence, clean hands) bar relief even where elements established. In conflicts, equity prevails per s.49 Senior Courts Act 1981. Modern application involves identifying the relevant maxim (e.g., 'equity follows the law' limits intervention), checking for statutory modification (Trustee Acts, LPA 1925), and applying precedent-structured discretion. Key triggers include: informal property arrangements (constructive trusts), fiduciary relationships (strict loyalty duties), and situations where damages cannot adequately compensate (unique goods, continuing wrongs).

Students wrongly claim the Judicature Acts abolished law/equity distinctions—they fused administration only, not substance. Another error: treating equity as purely discretionary when modern equity is largely rule-bound through precedent. Reciting maxims mechanically without application wastes marks—link them to specific doctrines and cases. Don't overstate differences: there's significant convergence (e.g., causation principles in AIB v Redler). Missing statutory reforms (LPA 1925, Limitation Act 1980) shows poor preparation. For essays, failing to engage the fusion debate or comparative perspectives (remedial constructive trusts in Canada) yields pedestrian answers. Always distinguish procedural fusion from substantive distinction.