The officious bystander is a metaphorical figure of English law and legal fiction, developed by MacKinnon LJ in Southern Foundries (1926) Ltd v Shirlaw[1] to assist in determining when a term should be implied into an agreement. While the officious bystander test is not the overriding formulation in English law today, it provides a useful guide. The suggested approach is to imagine a nosey, officious bystander walking past two contracting parties and asking them whether they would want to put some express term into the agreement. If the parties would instantly retort that such a term is "of course" already mutually part of the agreement then it is apt for implication.
- ^ [1939] 2 KB 206