A more thorough explanation:

The sole-actor doctrine is a rule in agency law that holds a principal responsible for the actions of their agent, even if the agent acted fraudulently. This means that if an agent acts on behalf of their principal in a fraudulent manner, the principal is still held accountable for the agent's actions.

Let's say that John hires Jane to sell his car for him. Jane tells a potential buyer that the car has never been in an accident, even though she knows that it has. The buyer purchases the car and later finds out about the accident. The buyer can sue both Jane and John for fraud, even though John had no knowledge of Jane's misrepresentation.

This example illustrates the sole-actor doctrine because John, as the principal, is held responsible for Jane's fraudulent actions, even though he had no knowledge of them.