The equitable jurisdiction 

Equity is a distinct body of doctrine, developed by the Court of Chancery alongside the common law, which supplements and corrects it. Australian law treats it as distinct and still living, and that starting point shapes everything else in this subject.

The three jurisdictions

The traditional classification remains the most useful way to organise the field.

• Exclusive — rights recognised only in equity, which the common law never protected at all: the trust, the fiduciary obligation, the equity of redemption, equitable estates and interests. If there is no common law right, the jurisdiction is exclusive.
• Concurrent — a common law right for which equity provides its own, usually better, remedy: specific performance of a contract, an injunction against a tort, relief against penalties and forfeiture.
• Auxiliary — equity assisting the enforcement of a common law right without creating one, historically through discovery, and today through freezing and search orders.

Fusion, and the Australian position

The Judicature legislation of the nineteenth century, replicated across Australia, allowed one court to administer both bodies of law and to grant both kinds of remedy. What it fused was the administration, not the rules.

Australian courts have been notably firm about this. Reasoning that treats equitable and common law doctrines as interchangeable — applying common law remoteness to equitable compensation, say, or contributory negligence to a breach of fiduciary duty — is criticised as the fusion fallacy. The label is Australian, and the insistence behind it is stronger here than in England or Canada.

The practical consequence for a student is precise: identify whether the right you are asserting is legal or equitable before selecting rules about causation, remoteness, defences or limitation, because the answers differ and the differences are not accidental.

Equity acts in personam

Equity's orders operate against the conscience of the defendant rather than directly on property or on the world. Historically this is why disobedience was contempt rather than a debt, and why equity could act on a defendant within the jurisdiction in respect of foreign land. It also explains the discretionary character of equitable relief: the court is asking what conscience requires of this defendant, not applying a tariff.

The maxims

The maxims are organising ideas distilled from the cases. They are not rules and do not decide anything by themselves; used carelessly they produce assertion in place of reasoning. Walsh v Lonsdale (1882) 21 Ch D 9¹ is the classic illustration of "equity treats as done that which ought to be done": a tenant entitled to a lease under a specifically enforceable agreement was treated as if the formal lease already existed. reasoning. Used properly they explain why a line of authority runs as it does.

• Equity will not suffer a wrong to be without a remedy — the historical impulse, though not a licence to invent relief today.
• Equity follows the law — equity respects legal rights and does not lightly displace them.
• He who seeks equity must do equity, and he who comes to equity must come with clean hands — the plaintiff's own conduct matters, though the misconduct must have a sufficient connection to the relief claimed.
• Delay defeats equity — laches, distinct from a limitation period, and turning on prejudice and acquiescence rather than the passage of time alone.
• Equity looks to substance rather than form, and regards as done that which ought to be done — the source of the rule that a specifically enforceable agreement passes an equitable interest.
• Equity will not assist a volunteer, and will not perfect an imperfect gift — subject to real exceptions, which is where trusts problems are often decided.
• Where the equities are equal, the first in time prevails — the foundation of the priorities rules.

Unconscionability as the organising idea

Modern Australian equity explains much of its content by reference to unconscionable conduct: the unconscientious assertion or retention of a legal right. This is a standard, applied through established categories — unconscionable dealing, undue influence, estoppel, fiduciary obligation — and not a free-standing discretion to relieve against unfairness. Australian courts have repeatedly declined to treat it as the latter. An answer that reasons directly from "this seems unconscionable" to a remedy, without working through a category, is doing the thing the cases warn against.

Applying this in a problem question

1. Identify whether the right in question exists at law, in equity, or both.
2. Name the jurisdiction — exclusive, concurrent or auxiliary — because it disciplines what follows.
3. Work within an established category rather than from unconscionability at large.
4. Keep equitable rules of causation, defence and limitation separate from their common law counterparts.
5. Remember relief is discretionary, and address the discretionary factors expressly.

Where the authority sits

Case law, with the Judicature provisions of each jurisdiction's supreme court legislation governing the administration of the two bodies of doctrine, and trustee, conveyancing and limitation statutes modifying particular parts of it.