When an agent contracts with a third party and names the principal then generally the principal alone can sue and be sued on the contract. This rule can be excluded by express and implied terms. Even if the agent signed the contract without qualification the agent will not be liable if it is clear from the body of the contract that the agent contracted only as agent . If the agent discloses the existence but not the name of the principal then the position is similar but subject to intention.

Apart from ratification, a principal is bound by the acts of the agent within the actual authority, express or implied. The common law rule has been extended by statute.