## Facts

- A police superintendent publicly offered a monetary reward for information that would secure the arrest and conviction of a particular offender. The offer was circulated through a widely distributed handbill and was therefore intended to reach an open and indefinite class of potential performers.
- Officer Gibbons, a member of the same police force, acquired decisive information that satisfied the terms of the offer. At the moment he first obtained the information, however, he had not yet read or heard about the reward.
- Before transmitting the information to his immediate superior, Gibbons was made aware of the printed handbill and thus became conscious that the superintendent had promised payment to anyone who supplied the necessary intelligence.
- After obtaining this knowledge, Gibbons forwarded the information through the usual police channels, causing the arrest to occur. He then submitted a claim for the reward.
- The superintendent resisted payment, contending that an individual who was ignorant of the reward at the time of initially acquiring the information could not later rely on the offer merely because he learned of its existence before physically communicating the facts.
- The matter came before the Queen’s Bench Division, which treated the dispute as turning on the timing of knowledge in relation to completion of performance under a unilateral contract.

## Issues

1. In a unilateral reward contract, must the offeree possess knowledge of the offer at the precise moment the act begins, or is awareness during the course of performance sufficient?
2. Does the act of forwarding information that has already been obtained, but not yet communicated, amount to “performance” for the purpose of acceptance?
3. If knowledge arises after the essential facts are first acquired but before the act is fully carried out, does that sequence satisfy the requirement that acceptance be “in response to” the offer?

## Decision

- The court held that acceptance of a unilateral reward contract is complete when the offeree performs the requested act while conscious of the offer. Although Gibbons collected the information before learning of the reward, the act had not yet been completed because the offer expressly required that the information be “given” or “communicated” to the authorities.
- Because Gibbons gained knowledge of the reward before the decisive step of communication, he performed the final element of the offer with the requisite awareness. Consequently, the court awarded him the promised sum.
- The ruling rejected a strict view that knowledge must exist at the very inception of performance. Instead, it treated the contract as accepted so long as the offeree is aware of the offer at some point before the performance is fully executed.
- The judgment preserved the principle that a unilateral contract cannot be enforced by a person who finishes the entire performance in ignorance of the offer; yet it acknowledged a practical middle ground where partial performance without knowledge can be completed with knowledge and still bind the offeror.

## Legal Principles

- Unilateral contract formation: An offer of reward to the world at large becomes binding when an offeree completes the stipulated act with knowledge of the reward. Silence or lack of acknowledgment to the offeror is not fatal, because the offer invites acceptance through conduct rather than through a separate promise.
- Knowledge requirement: The court emphasized that performance must be motivated, at least in part, by the offer. If the claimant had delivered the information solely from a sense of duty, never having heard of the reward until after submission, that claimant would have lacked contractual intent and therefore would have no right to enforce payment.
- Stage-based analysis of performance: Where the requested act is divisible—here, obtaining information and then supplying it—knowledge acquired during an intermediate stage is adequate. Only upon final completion does the contract crystallize.
- Public policy considerations: The judgment protects the integrity of reward offers by preventing windfall claims from unintended beneficiaries, whilst also ensuring that offerors cannot evade liability by seizing on technical lapses when the claimant’s decisive conduct is clearly referable to the offer.

## Conclusion

Gibbons v Proctor confirms that, in unilateral reward contexts, contractual acceptance is achieved when the claimant completes the act demanded by the offer while aware of its terms, even if some preliminary steps occurred earlier without such knowledge. The decision draws a practical line between cases of total ignorance throughout performance—where recovery is barred—and situations where awareness arises before the act is fully executed, permitting enforcement of the promise.


Gibbons v Proctor (1891) 64 LT 594