## Facts

- Hartley, a sailor, was employed aboard a ship captained by Ponsonby, with an original crew of thirty-six.
- Nineteen crew members deserted during the voyage, leaving the vessel seriously undermanned.
- The diminished crew made the continuation and completion of the voyage significantly more dangerous and demanding for those who remained.
- In response, the captain promised the remaining sailors extra wages if they fulfilled the voyage and returned the ship to port.
- After the voyage's successful completion, Ponsonby refused to pay the extra wages, arguing the sailors merely fulfilled their existing contractual duties.
- Hartley initiated legal proceedings seeking to enforce the captain’s promise of additional payment, arguing that, under the circumstances, the crew performed beyond their contractual obligations.

## Issues

1. Whether the remaining sailors provided consideration for the captain’s promise of extra pay by performing duties exceeding those in their original contract.
2. Whether the performance of contractual duties, after a fundamental change in circumstances, can amount to valid consideration for a new agreement.
3. Whether the promise of additional wages was enforceable in light of the law on performance of existing contractual obligations.

## Decision

- The court held that the circumstances, specifically the substantial reduction in crew, made the voyage far more dangerous and changed the nature of the sailors' obligations.
- The sailors' agreement to continue under such hazardous conditions constituted the assumption of new obligations beyond the original contract.
- The extra risk and workload undertaken by the remaining crew were considered sufficient consideration for the captain’s promise of additional pay.
- The promise of additional payment was therefore enforceable.

## Legal Principles

- Performance of a pre-existing contractual duty does not usually constitute valid consideration for a new promise.
- An exception arises when unforeseen circumstances fundamentally alter the nature of the contractual obligations, so that continued performance exceeds what was originally promised.
- Where duties become so onerous or risky that the contractual framework changes, further performance can amount to new consideration.
- Practical benefits and the contextual transformation of a party’s obligations may justify enforcement of variations to contractual terms.

## Conclusion

The court in Hartley v Ponsonby held that when unforeseen events fundamentally change a contract’s circumstances, and one party undertakes duties substantially beyond those originally agreed, that party can provide valid consideration for a new promise. This case established an important limitation on the rule that performance of an existing contractual duty cannot be good consideration for a fresh promise, emphasizing the necessity of evaluating contracts within their factual context.

Hartley v Ponsonby (1857) 7 El & Bl 872