Template:Authority capsule
Whether the fellow who purports to sign the contract for your counterparty has any ostensible grounds to do — whether she is properly appointed by the board or, by dint of her role within the organisation, has the general authority to sign — so is a question of her authority. Here the law of agency lends an innocent contracting party a hand, with the doctrine of ostensible authority meaning one can rely on someone who seems to have appropriate authority even if she doesn’t, as long as you don’t (or can not reasonably have been expected to) know that.