Constituent ‘Parts’ of a Contract (AQA A-Level Law): Revision Notes
Constituent 'Parts' of a Contract
Introduction to contract formation
Under common law, a valid contract requires three essential elements to be present. These constituent parts must all exist for a contract to be legally enforceable. The three key parts are:
- Agreement – where a valid offer is followed by a valid acceptance
- Consideration – something is given in return for something promised, proving that the agreement exists
- Intention to create legal relations – a clear intention to be bound by the agreement from both parties
All three elements must be satisfied for a contract to be valid and enforceable. If any one of these elements is missing, no legally binding contract exists.
This note focuses primarily on agreement and consideration, which form the foundation of contractual obligations.
Agreement
Agreement is the first essential element of a valid contract. It is formed when one party makes a valid offer and the other party validly accepts that offer. Without both offer and acceptance, no contract can exist.
Offer
An offer is a clear statement made by one party (the offeror) which sets out the specific terms they are willing to be bound by. The offer must be communicated to the other party and must be sufficiently certain in its terms.
The key characteristics of a valid offer include:
- It must be distinguished from an invitation to treat (see below)
- It must set out definite terms that can be accepted
- It must be communicated to the offeree
- It creates the power of acceptance in the offeree
Unilateral Contracts as Offers
Unilateral contracts provide a specific example of offers. In such contracts, an advertisement can operate as a form of reward.
How it works:
- The person reading the advertisement does not need to communicate their intention to comply
- They simply need to perform the required action to accept the offer
- Once they complete the specified action, they become entitled to the reward
This differs from bilateral contracts where both parties exchange promises before performance.
Acceptance
Acceptance occurs when the party receiving the offer (the offeree) agrees to the terms set out in the offer. No contract is formed until acceptance takes place. There must be a valid offer to enable valid acceptance.
The law has developed specific rules to govern acceptance in different situations:
The Postal Rule
The postal rule was established in Adams v Lindsell (1818). This rule states that if the post is an accepted and appropriate method of acceptance, then acceptance is complete when the letter is posted, even if that letter is subsequently lost in the post and never received by the offeror.
This creates an exception to the general rule that acceptance must be communicated.
Modern communication methods such as text messages, emails, and other electronic means have required new rules to be developed. For these methods, acceptance is usually complete upon receipt of the communication, not upon sending. This contrasts with the postal rule and reflects the instantaneous nature of electronic communication.
Invitation to treat
An invitation to treat is a preliminary communication that precedes an offer. It is passive conversation which invites another person to make an offer, rather than being an offer itself.
Common examples of invitations to treat include:
- Goods displayed on shop shelves
- Advertisements in newspapers (generally)
- Catalogues and price lists
The distinction between an invitation to treat and an offer is crucial, as only offers can be accepted to form a contract. An invitation to treat merely invites negotiations and cannot be "accepted" to create a binding agreement.
Consideration
Consideration is the second essential element of a valid contract. It provides the mechanism for enforcing informal contracts (those not made under seal).
Rationale for consideration
In the absence of formal agreements under seal, the law required a method of enforcing informal contracts. This led to the creation of the doctrine of consideration.
The concept of consideration arose from the need to demonstrate that something of value was exchanged. The Latin phrase quid pro quo (meaning "something for something") captures this principle. Consideration represents the price paid for goods or services, or more broadly, the value exchanged between the contracting parties.
The most common form of consideration is money paid by the offeree to the offeror in return for goods and services. However, consideration can take many forms, provided it has some value in the eyes of the law.
While defining consideration precisely remains difficult, its essential characteristic is that it represents something of value given by one party in exchange for the promise or performance of the other party.
Consideration and privity
The doctrine of privity of contract is closely linked to consideration. This doctrine establishes an important limitation on who can enforce a contract.
The principle works as follows:
Worked Example: Privity of Contract
If Party A promises "I'll mow your lawn" (the promise), Party B must provide consideration such as "I'll pay you £20" (the consideration).
Who can enforce the contract?
- Only the person who has provided, or agreed to provide, the consideration (Party B who will pay £20) can enforce the promise (the lawn-mowing service)
- Similarly, only the person who made the promise can enforce the right to receive the consideration
Result: Only those persons who are privy (parties) to the contract can sue if they are denied the agreed benefit. Third parties who are not part of the original agreement generally cannot enforce the contract, even if they might benefit from it.
This principle ensures that contractual obligations remain between the contracting parties and prevents outsiders from claiming rights under agreements to which they were not party.
Consideration and economic duress
In some contractual situations, particularly in building and construction works, one party may realize that they cannot fulfill their obligation as originally agreed. This creates a practical problem where failure to complete on time could have serious, potentially catastrophic consequences.
To ensure the contract is completed on time, one party may request additional payment beyond what was originally agreed. The question then arises: is this promise to pay extra money legally binding?
The leading case is Williams v Roffey (1990), which established that a promise to pay extra money will only be binding if the party promising the extra payment obtains a further practical benefit beyond simply receiving the original performance of the contract.
The Economic Duress Limitation
The promise to pay extra money will only be enforceable if it was given freely and without economic duress. Economic duress occurs when one party makes a threat to damage the other's financial interests, effectively forcing them to agree to new terms.
If economic duress is present, the promise to pay extra may be voidable, even if there was consideration. The law seeks to balance the need for commercial flexibility with protection against exploitation.
Exclusion and exemption clauses
While not strictly one of the three constituent parts, exclusion clauses (also called exemption clauses) are important contractual terms that affect parties' obligations.
An exclusion or exemption clause is a term within a contract which seeks to exclude or limit the liability of the party inserting it from certain contractual breaches that may occur in the future.
Historical problems and development
Historically, exclusion clauses operated unfairly against the weaker party, particularly where the parties entered the contract on an unequal footing with significantly different bargaining strengths. One party (typically a business) could impose unfair terms that left the other party (typically a consumer) without effective remedies.
The law has evolved to provide greater protection. There is now substantial judicial control (through case law) and statutory control (through legislation) over exemption clauses.
However, the results remain mixed for parties seeking to rely on these clauses, as courts carefully scrutinize them to ensure fairness.
Exam guidance
Assessment information
This content is assessed in Paper 1 of the AQA A-Level Law examination.
Key exam tips
When answering questions on constituent parts of a contract, remember to:
- Always identify all three essential elements: agreement, consideration, and intention to create legal relations
- For problem questions, work through each element systematically
- Use Latin terms appropriately (such as quid pro quo) to demonstrate familiarity with contract law principles
- Cite relevant case law accurately – particularly Adams v Lindsell (1818) for postal rule and Williams v Roffey (1990) for consideration and practical benefit
- Distinguish clearly between offer and invitation to treat in scenario questions
- Explain the concept of privity when discussing consideration
For 10-mark scenario questions on offer and acceptance:
- Identify whether a valid offer exists
- Determine the method and timing of acceptance
- Apply relevant case law to support your conclusions
- Reach a clear conclusion about whether a contract has been formed
Remember!
Key Points to Remember:
- A valid contract requires three constituent parts: agreement (offer + acceptance), consideration (quid pro quo), and intention to create legal relations
- Offer must be distinguished from invitation to treat – only offers can be accepted to form contracts
- The postal rule (Adams v Lindsell 1818) creates an exception where acceptance is complete on posting, not receipt
- Consideration is something of value exchanged – it proves the agreement exists and enables contract enforcement
- Privity means only parties to the contract who have provided consideration can enforce it
- Promises to pay extra money require practical benefit (Williams v Roffey 1990) and must be free from economic duress
Key Terms:
- Offer – statement setting out terms the offeror agrees to be bound by
- Acceptance – agreement to the terms of the offer
- Offeror – party making the offer
- Offeree – party receiving the offer
- Invitation to treat – preliminary communication inviting offers
- Consideration – something of value exchanged between parties
- Quid pro quo – something for something
- Privity – only parties to the contract can sue on it
- Economic duress – threat to damage someone's financial interests
- Exclusion clause – term limiting or excluding liability
Critical Cases:
- Adams v Lindsell (1818) – postal rule for acceptance
- Williams v Roffey (1990) – consideration, practical benefit, and economic duress