Identify consideration and existing duties
Separate legal sufficiency from price fairness and examine the promise actually exchanged.
Section 3.1.4 · Consideration and promissory estoppel
Exam scope and assessment notes
A Level · section 3.1.4. Original educational scenarios about the law of England and Wales, checked on 14 October 2026. Model answers are formative reasoning, not advice about a real dispute, Cambridge marks or predicted grades. Read the exact statute, case and exam-year source where a rule is disputed or changes. A larger annotated authority bank, full unseen papers and specialist law-teacher review remain outstanding.
Before you begin
- Read a short source carefully and separate its rule from the facts
- Explain which element a fact supports and what is still uncertain
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What should a legal problem answer connect?
What you will learn
- Explain sufficiency, adequacy and past consideration
- Compare public, contractual and third-party duties
Locate the bargained-for exchange
Consideration is the legally recognised exchange supporting a simple contract. It must move from the promisee but need not benefit the promisor directly. A court generally asks whether it is sufficient in law, rather than whether the bargain is economically adequate. A low price is not by itself lack of consideration.
An act already completed before an unsolicited promise is generally past consideration, illustrated by Re McArdle. An earlier requested act can fall within a qualified exception where payment was understood and would have been enforceable if promised in advance. Do not turn every later thank-you promise into that exception.
Specify the existing duty
Simply doing a public duty normally supplies no new consideration, though doing more can. Performance of an existing obligation owed to a third party can be consideration for a different promisor. Performance of an existing contractual duty owed to this promisor traditionally raises Stilk v Myrick; Williams v Roffey recognises practical benefit in qualifying promises to pay more, absent fraud or economic duress.
That practical-benefit analysis is not an automatic rule for reducing debts. Identify additional work, benefit, bargaining pressure and any required variation formalities. Rock Advertising confirms the significance of no-oral-modification clauses and did not resolve the separate consideration debate by abolishing the debt rule.
Sources for this lesson
Pause and explain
Must sufficient consideration always match the market value of what is received?
Worked example
A buyer agrees to pay £1 for a used folder worth much more. A student says the consideration is invalid because the price is inadequate. Evaluate.
Show the worked solution
- Payment is a bargained-for exchange.
- Legal sufficiency differs from market value.
- Check other formation and validity issues separately.
Answer The £1 payment can be sufficient consideration despite being economically inadequate. A poor bargain alone does not establish absence of consideration; intention, capacity or another validity issue would require separate facts.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Guided: Explain the £1 folder bargain using the two concepts.
Give me a hint
Ask value in law before fairness of price.
Compare my reasoning
- Identify promised payment.
- Separate sufficiency and adequacy.
- Retain other formation questions.
The promised payment is a legal exchange even though the price may be poor. Courts do not ordinarily require equivalent market value to establish consideration, while other validity requirements remain separate.
Look for these in your work
- Identifies exchange
- Distinguishes concepts
- Preserves validity questions
Independent: A neighbour completes an unsolicited repair and only afterwards receives a promise of £30. What is the consideration issue?
Give me a hint
Compare the act and promise chronologically.
Compare my reasoning
- The act precedes the promise.
- No prior request or understood payment is stated.
- Apply the general past-consideration rule.
The completed unsolicited repair is generally past consideration for the later promise. Without facts supporting the prior-request exception or another enforceable basis, gratitude alone does not supply a bargain.
Look for these in your work
- Uses chronology
- Uses missing request
- States qualified conclusion
Application: A builder seeks an extra fee for existing work. Identify the questions a practical-benefit argument must answer.
Give me a hint
Existing work is not automatically fresh consideration.
Compare my reasoning
- Identify a real practical benefit and the duty owed.
- Examine fraud or economic duress.
- Check agreed variation formalities.
The analysis needs the existing obligation, any qualifying practical benefit, absence of disqualifying pressure and compliance with applicable variation formalities. It must not infer enforceability merely from the builder's demand or extend the rule automatically to part-payment of debt.
Look for these in your work
- Identifies benefit
- Examines pressure
- Checks formalities
Common mistakes
- Requiring a fair market price
- Treating all past acts as requested bargains
- Applying practical benefit automatically to debts
What can you explain now?
Must sufficient consideration always match the market value of what is received?
Compare with the explanation
No
Legal sufficiency and economic adequacy are distinct questions.
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Make it stick
Must sufficient consideration always match the market value of what is received?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.