Hard Concepts in Law · United Kingdom
The hardest concepts in United Kingdom law
20 ideas, 9 areas of law, one picture for each.
These are the ideas that students find hard, across 9 areas of law. Each one has its own page with an everyday picture of how the rule is built, the usual mistakes, a worked example and a trap question.
Step 1Constitutional law
Parliamentary sovereignty and the Human Rights Act
The editor’s margin note
Parliament can make or unmake any law, and no court can strike down an Act of Parliament, however unjust it may seem. The Human Rights Act asks courts to read legislation in line with the Convention rights where that is possible and, where it is not, to declare it incompatible without invalidating it.
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Step 2Administrative law
Judicial review and its grounds
The lifeguard at the pool’s edge
Judicial review is the High Court’s power to check that a public body acted lawfully, not that it chose wisely. The usual grounds are illegality, irrationality and procedural unfairness, and the usual remedy is to quash the decision and send it back.
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Step 3Legal method
Precedent, ratio decidendi and obiter dicta
The recipe and the cook’s chat
A court must follow the legal reasoning that was necessary to decide an earlier case in a higher court and, with some exceptions, in its own court. That binding part is the ratio decidendi, and everything else the judges said along the way is obiter dicta, which may persuade but does not bind.
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Step 4Legal method
Statutory interpretation
The park sign that says no vehicles
Courts read an Act to find what Parliament meant, starting from the words in their context and in the light of the Act’s purpose. The old rules of thumb, the literal, golden and mischief rules, now work together inside one approach that gives the text first place.
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Step 5Contract law
Consideration and promissory estoppel
The turnstile at the stadium
A promise made for nothing is not an enforceable contract unless it is made in a deed; the law asks what each side gave, not whether the exchange was fair. Promissory estoppel is a narrow exception that can stop a person going back on a promise to give up part of their rights, but it protects the person relying and does not found a claim of its own.
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Step 6Contract law
Privity and third-party rights
The table booked in a friend’s name
Only the parties to a contract can sue on it, so an outsider cannot normally enforce a promise made for their benefit. The Contracts (Rights of Third Parties) Act 1999 lets an identified outsider enforce a term if the contract says so or the term purports to benefit them, unless the parties did not intend that.
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Step 7Contract law
Mistake and misrepresentation
The label on the jar
A misrepresentation is a false statement of fact that induces a contract, and it can let the misled party rescind or claim damages. A mistake is an error in what the parties believed, and only a narrow band of mistakes stops a contract from binding at all.
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Step 8Contract law
Penalty clauses and liquidated damages
The library late fee
A clause that fixes in advance what a party must pay on breach is enforceable if it protects a legitimate interest of the innocent party and is not out of all proportion to that interest. A clause that merely punishes the party in breach is a penalty and cannot be enforced.
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Step 9Tort law
Duty of care and the incremental approach
The stepping stones across a stream
In negligence the claimant must first show that the defendant owed them a duty of care, and foreseeable harm alone does not create one. Courts now decide new duty questions step by step, by analogy with established categories, rather than by applying one general test.
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Step 10Tort law
Causation: the but-for test and its exceptions
The domino run and the second pusher
A claimant must show that the defendant’s breach caused the damage, and the usual test asks whether the harm would have happened anyway without the breach. In a few settled situations, such as asbestos-related disease caused by several employers, the courts relax the test so that the claimant is not left without a remedy.
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Step 11Tort law
Remoteness of damage
Ripples on a pond
Even when a breach caused the damage, a defendant in tort is liable only for damage of a kind that was reasonably foreseeable when the breach occurred. The defendant takes the claimant as they find them, so the extent of the harm need not be foreseeable if its kind was.
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Step 12Tort law
Vicarious liability
The kite and its string
An employer can be held liable for a tort committed by an employee, or by someone in a relationship like employment, even though the employer did nothing wrong. Liability turns on two questions: whether the relationship is of a kind that can ground liability, and whether the wrong is so closely connected with the job that holding the organisation responsible is fair.
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Step 13Tort law
The rule in Rylands v Fletcher
The overflowing bath upstairs
The rule in Rylands v Fletcher makes a person who, in a non-natural use of their land, accumulates something likely to do mischief if it escapes liable for the damage caused when it does escape. It is now treated as a branch of private nuisance, protects interests in land, and requires that damage of the relevant kind was foreseeable.
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Step 14Trusts and equity
The three certainties of an express trust
The parcel at the post office
An express trust is valid only if there is certainty of intention to create a trust, certainty of the property and interests, and certainty of the objects, meaning the beneficiaries. If any one is missing there is no trust, and the property usually stays with the person who owned it.
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Step 15Trusts and equity
Resulting and constructive trusts
The boomerang and the referee’s whistle
A resulting trust sends the benefit of property back to the person who provided it, where the law presumes they did not mean to give it away. A constructive trust is imposed by the court, whatever the parties intended, where it would be unconscionable for the legal owner to deny another person’s interest.
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Step 16Trusts and equity
Proprietary estoppel
The staircase built on a promise
Proprietary estoppel gives a remedy to a person who relied on an assurance that they would have some right in another’s property and who suffered detriment, so that it would be unconscionable for the owner to go back on it. The court has a wide discretion over the remedy, which must be proportionate to the detriment and the expectation.
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Step 17Land law
Registered land and overriding interests
The hotel register and the guest in the room
In England and Wales most land is registered, and a buyer is generally bound only by interests that the register shows or that the Land Registration Act 2002 says bind without registration. The most important hidden interest belongs to a person in actual occupation of the land, which can bind a buyer although the register is silent.
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Step 18Restitution
Unjust enrichment
The ledger with a wrong entry
Unjust enrichment gives a claim for the value of a benefit the defendant received at the claimant’s expense, where the law regards keeping it as unjust, as when money is paid by mistake. The usual questions are whether the defendant was enriched, whether at the claimant’s expense, whether the enrichment was unjust, and whether a defence applies.
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Step 19Criminal law
Oblique intention and the Woollin direction
The scar and the surgeon
In English criminal law a person intends a result if it is their aim or purpose, and a jury may also find intention where the result was a virtual certainty of the defendant’s actions and the defendant realised that. This second route is oblique intention, and it is evidence from which a jury may find intention, not a definition of it.
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Step 20Criminal law
Accessory liability and joint enterprise
The backstage crew of a play
A person who intentionally assists or encourages another to commit a crime, knowing the essential facts, can be convicted of that crime as a secondary party. Since R v Jogee, foresight that the principal might commit a further crime is evidence from which intention to assist or encourage may be inferred, but it is not itself enough for guilt.
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Read this first
The United Kingdom has three legal systems: England and Wales, Scotland, and Northern Ireland. These pages mostly describe the law of England and Wales and say where Scots law differs when it clearly does; Northern Ireland law is often similar to English law but is not covered separately. Parliament is sovereign, but the devolved legislatures also make law within their powers. Each page states the usual formulation of the rule and names landmark decisions; check the primary sources before relying on any rule.
These pages are educational overviews. They are not legal advice and not a substitute for the primary sources.