The authority to act on behalf of his principal. An insurance broker may act at one time for the insured (i.e. placing insurance as instructed) and at other times for the insurer, e.g. collecting the premium. In order to determine who is bound by the agent’s act it is necessary to ascertain for whom he was acting in regard to the relevant issue. An agent’s authority may be express as when acting on specific instructions or it may be implied (actions taken in accordance with prevailing custom) or apparent (or ostensible) authority (actions based on appearances). Where the agent acts without authority and the principal becomes obligated the agent may be liable to his principal. See IMPUTED KNOWLEDGE.