Acceptance by conduct in English contract law

The formation of a contract in English law requires, at its most elementary, an offer, an acceptance, consideration, and an intention to create legal relations. Whilst acceptance is often communicated expressly – by letter, email, or spoken word – the common law has long recognised that a party may accept an offer through conduct alone. Acceptance by conduct arises where a party, without uttering words of agreement or affixing a signature, behaves in a manner that objectively demonstrates assent to the terms proposed. It is a doctrine born of commercial pragmatism, reflecting the reality that business is frequently transacted not through meticulously executed documents but through the practical acts of performance, delivery, and payment.

This guide examines the historical development of acceptance by conduct, traces the leading authorities from the nineteenth century to the present day, and considers the doctrine’s limits and its interaction with related principles such as the battle of the forms.

The doctrinal foundation

The objective principle

English contract law does not enquire into a party’s private intentions. Whether acceptance has occurred is assessed on the objective principle: would a reasonable person, observing the conduct of the alleged acceptor, conclude that they intended to be bound by the offer’s terms? This was famously articulated by Blackburn J in Smith v Hughes (1871) LR 6 QB 597, and it is the objective principle that gives acceptance by conduct its doctrinal coherence. A party cannot secretly harbour reservations whilst acting in every outward respect as though they have agreed; the law will hold them to the bargain their conduct suggests.

Acceptance is “any words or conduct which objectively indicates that the offeree intends to be bound by the offer’s terms”. The offeree’s inner motives for accepting are immaterial: Williams v Carwardine (1833) 110 ER 590.

Silence distinguished

A critical boundary must be drawn at the outset. Acceptance by conduct is not acceptance by silence. In Felthouse v Bindley [1862] EWHC CP J35, an uncle wrote to his nephew offering to buy a horse, adding: “If I hear no more about him, I consider the horse mine.” The nephew intended to sell but never communicated this. The court held that there was no contract. Silence, standing alone, does not amount to acceptance – a principle that protects offerees from having obligations thrust upon them by the unilateral dictates of the offeror.

The distinction is important: acceptance by conduct requires positive action consistent with the terms of the offer. The conduct must be clear, unequivocal, and referable to the offer in question. Where such action is present, the law is willing to dispense with express communication.

Historical development: the nineteenth-century foundations

Brogden v Metropolitan Railway Company (1877) 2 App Cas 666

No treatment of acceptance by conduct can begin anywhere other than with Brogden, the locus classicus of the doctrine. The facts are well known but repay careful examination, for they illustrate precisely the kind of commercial reality the principle exists to address.

Brogden had supplied coal to the Metropolitan Railway Company informally for some years. The parties sought to formalise the arrangement, and the railway company sent Brogden a draft contract. Brogden filled in certain blanks – including inserting the name of an arbitrator – marked the document “approved,” and returned it to the railway company’s agent, who placed it in a desk drawer. No one on behalf of the railway company ever signed the draft or communicated formal acceptance of the amended terms.

Despite this, both parties proceeded to act upon the terms of the draft for a considerable period. Coal was supplied, delivered, and paid for in accordance with its provisions. When a dispute eventually arose and Brogden denied the existence of any binding contract, the House of Lords disagreed emphatically. Lord Blackburn held that although the draft had never been formally executed, the conduct of both parties – in ordering, supplying, and paying for coal on the terms set out in the draft – constituted acceptance of those terms. A binding contract had been formed through performance.

The significance of Brogden cannot be overstated. It established, at the highest judicial level, the following propositions:

1. Formal execution is not necessary. A contract may come into existence without signatures or express words of acceptance, provided the parties’ conduct evinces agreement.
2. Mutual conduct suffices. Where both parties perform in accordance with proposed terms, their reciprocal conduct amounts to offer and acceptance.
3. The moment of formation may be imprecise. The House of Lords acknowledged the difficulty of identifying the precise moment at which the contract came into being, but held that this did not prevent its existence.

Carlill v Carbolic Smoke Ball Company [1893] 1 QB 256 (Court of Appeal)

Carlill is most celebrated for its treatment of unilateral contracts and the sufficiency of advertisements as offers, but it is also a landmark in the development of acceptance by conduct. The Carbolic Smoke Ball Company advertised that it would pay £100 to anyone who contracted influenza after using its smoke ball as directed, depositing £1,000 with the Alliance Bank to demonstrate sincerity. Mrs Carlill purchased and used the smoke ball, contracted influenza, and claimed the reward.

The Court of Appeal held that Mrs Carlill’s conduct – purchasing and using the smoke ball in accordance with the advertised directions – constituted acceptance of the company’s offer. In the context of a unilateral contract, the court reasoned, the very nature of the offer dispenses with the need for prior communication of acceptance. Performance of the stipulated act is the acceptance. Lindley LJ and Bowen LJ each emphasised that requiring express notice of acceptance would render the offer “illusory” and commercially absurd.

Carlill thus extended the principle of acceptance by conduct into the specific domain of unilateral offers, where it remains foundational to this day.

Twentieth-century consolidation

Entores Ltd v Miles Far East Corporation [1955] 2 QB 327

Whilst Entores is principally an authority on the receipt rule for instantaneous communications, Denning LJ’s judgment contains an important restatement of the general principle that acceptance must be communicated – but that the law recognises conduct as a valid mode of communication. The case confirmed that the nature of the communication matters less than the fact that the offeror is made aware of the acceptance, whether by words, writing, or action.

The battle of the forms: Butler Machine Tool Co Ltd v Ex-Cell-O Corporation (England) Ltd [1979] 1 WLR 401

The “battle of the forms” arises where commercial parties exchange competing sets of standard terms, each purporting to govern the transaction. In Butler Machine Tool, the Court of Appeal analysed the sequence of communications between the parties. The seller quoted a price on its own terms (including a price variation clause); the buyer placed an order on its own terms (which contained no such clause), accompanied by a tear-off acknowledgment slip. The seller signed and returned the slip.

Lord Denning MR sought to resolve such disputes by reference to the parties’ conduct and the totality of their communications. The majority (Lawton LJ and Bridge LJ), however, applied orthodox offer and acceptance analysis: the buyer’s order was a counter-offer, and the seller’s return of the acknowledgment slip was acceptance by conduct of the buyer’s terms. The seller’s act of signing and returning the slip, viewed objectively, indicated assent to the buyer’s conditions.

Butler Machine Tool demonstrates that acceptance by conduct operates even within the structured context of competing standard forms. It is the final act of conduct – the “last shot” – that typically determines whose terms prevail, a pragmatic if sometimes arbitrary resolution.

Modern developments

Reveille Independent LLC v Anotech International (UK) Ltd [2016] EWCA Civ 443

Reveille addresses the related question of what happens where an offer prescribes a particular mode of acceptance – specifically, a requirement for a signature – but the offeree accepts by conduct instead. The parties had negotiated a licensing agreement. The offer stipulated that acceptance required a signature, but the defendant acted in accordance with the agreement’s terms without ever signing.

The Court of Appeal held that where a prescribed mode of acceptance is intended for the benefit of the offeror, the offeror may waive it; but where it is for the benefit of the offeree, the offeree may waive it and accept by other means, including conduct, provided this does not prejudice the offeror. The court upheld the contract on the basis that the parties’ conduct – performance and payment in accordance with the agreement – was sufficient.

Reveille is a significant modern authority because it addresses a tension inherent in the doctrine: can conduct override an express stipulation as to the form of acceptance? The answer, pragmatically, is yes – but only where the party who stood to benefit from the formality has elected, through its own actions, to proceed without it.

TRW Ltd v Panasonic Industry Europe GmbH [2021] EWCA Civ 1558

TRW v Panasonic is one of the most important recent authorities on acceptance by conduct, decided in the context of a battle of the forms dispute with jurisdictional implications.

TRW, an English manufacturer, purchased goods from Panasonic. The parties exchanged competing sets of standard terms. Panasonic’s terms included a clause conferring jurisdiction on the German courts. The question before the Court of Appeal was whose terms governed the contract.

Applying traditional offer and acceptance analysis, the court held that TRW’s conduct in accepting delivery of the goods constituted acceptance of Panasonic’s counter-offer. By taking delivery and paying for the goods on the terms last proposed by Panasonic, TRW had, through its conduct, assented to Panasonic’s standard conditions – including the German jurisdiction clause.

The decision is notable for several reasons:

• It reaffirms the “last shot” doctrine in the battle of the forms, notwithstanding academic criticism of its sometimes arbitrary results.
• It demonstrates the high stakes of acceptance by conduct. TRW’s apparently unremarkable act of accepting delivery had the consequence of submitting to the jurisdiction of a foreign court – a result that commercial parties might not anticipate.
• It underscores the need for vigilance. Parties who receive goods or services on terms they have not expressly agreed to must be aware that their conduct in accepting performance may bind them to those terms.

The principles synthesised

Drawing together the threads of the case law from Brogden to TRW v Panasonic, the following principles govern acceptance by conduct in modern English law:

Principle	Authority
Acceptance may be communicated by conduct as well as by words	Brogden v Metropolitan Railway Co (1877)
The test is objective: would a reasonable person conclude from the conduct that the offeree intended to accept?	Smith v Hughes (1871); Brogden
Silence alone is insufficient; positive action is required	Felthouse v Bindley (1862)
Performance of the act stipulated in a unilateral offer constitutes acceptance	Carlill v Carbolic Smoke Ball Co (1893)
In a battle of the forms, accepting delivery or performing under the last set of terms proposed may constitute acceptance by conduct	Butler Machine Tool v Ex-Cell-O (1979); TRW v Panasonic (2021)
A prescribed mode of acceptance (e.g. signature) may be waived by the party for whose benefit it was stipulated	Reveille v Anotech (2016)
Conduct must be clear and unequivocal; ambiguous acts will not suffice	General principle; Brogden

Limitations and practical considerations

The conduct must be referable to the offer

Not every act of performance will amount to acceptance. The conduct must be referable to the specific offer in question. If a party’s actions are equally consistent with a pre-existing arrangement, a different contract, or mere negotiation, the court will not infer acceptance. In Brogden, the critical factor was that the parties’ conduct corresponded precisely with the terms of the draft contract, not with the earlier informal arrangement.

The offeree must have knowledge of the offer

A party cannot accept an offer of which they are unaware. This requirement, whilst more commonly discussed in the context of unilateral offers and rewards, applies equally to acceptance by conduct. The conduct must be performed in response to and with knowledge of the offer’s terms.

Identifying the moment of formation

One practical difficulty with acceptance by conduct is pinpointing the moment at which the contract comes into being. In Brogden, the House of Lords candidly acknowledged this difficulty. Where parties gradually slide from negotiation into performance, the precise instant of formation may be impossible to identify with certainty. The law’s response is pragmatic: it is enough that the court can determine that a contract has been formed, even if the exact moment is elusive. The relevant question is not “when?” but “whether?”

Commercial vigilance

TRW v Panasonic serves as a cautionary tale. In modern commerce, where standard terms are routinely exchanged, the simple act of accepting delivery, making payment, or commencing performance may have far-reaching contractual consequences. Parties who wish to avoid being bound by terms they have not expressly agreed must take active steps: they should communicate their objections clearly and should not, through their conduct, give the impression of acquiescence.

Conclusion

Acceptance by conduct is a doctrine rooted in the common law’s characteristic preference for substance over form. From Brogden‘s coal deliveries in 1877 to TRW‘s receipt of electronic components in 2021, the courts have consistently held that actions speak as loudly as words – and bind as firmly. The principle serves the needs of commerce, recognising that agreements are forged not only in the exchange of executed documents but in the daily acts of supply, delivery, and payment that constitute the lifeblood of trade.

Yet the doctrine is not without its risks. Acceptance by conduct may occur inadvertently, binding a party to terms it never consciously agreed to accept. The lesson for practitioners and commercial parties alike is clear: conduct carries legal weight. Those who perform under another’s terms, accept delivery of goods, or pay invoices without reservation may find that the law treats their actions as the clearest possible expression of assent.

See also: Acceptance by conduct cases