What is the doctrine of ultra vires ? What is the effect of an ultra vires contract?

Ultra vires acts are without legal authorization, because the act is not within the scope and type of acts that the corporation is legally empowered to perform. Traditionally, ultra vires acts were unenforceable as null and void. Today, courts allow the ultra vires defense when the contract is wholly executory on both sides. Most corporate statutes today give corporations broad powers and most corporate charters use general language to outline the activities in which the corporation proposes to engage. Thus, the doctrine is of less importance today than in the past.