A more thorough explanation:

Definition: Special non est factum is a legal term that means "it is not his deed." It is a type of pleading used to deny the execution of an instrument that is being sued on.

For example, if someone is being sued for not paying a debt, they may use special non est factum to deny that they ever signed the contract that created the debt. This type of pleading specifies the grounds on which the instrument's execution is invalid or nonbinding.

There are other types of non est factum pleadings as well:

• General non est factum: A broad, nonspecific denial that an instrument was executed or executed properly.
• Particular non est factum: Another term for special non est factum.
• Verified non est factum: A sworn denial that puts the validity of the instrument as well as the signature in question.

These different types of non est factum pleadings can be used in different situations depending on the specifics of the case.

Overall, special non est factum is a legal tool that can be used to deny the validity of a contract or other legal instrument. It is important for individuals to understand their legal rights and options when facing legal disputes.