A more thorough explanation:

Definition: General non est factum is a legal term that refers to the defense of "it is not my deed." It is used when a person claims that they did not sign a document or contract, and therefore should not be held responsible for it.

Example: John signed a contract to buy a car, but later realized that the contract was for a different car than the one he intended to buy. He could use the defense of general non est factum to argue that he did not sign a contract for the car he intended to buy, and therefore should not be held responsible for it.

This example illustrates how the defense of general non est factum can be used to dispute the validity of a contract or document.