By Lummina Law Firm
30 August 2026
Practical perspective for the decisions ahead.
You sign a shareholders' agreement. You sign an investment document. You execute a personal guarantee. Months later, you discover a provision that fundamentally changes your understanding of the transaction. Perhaps you believed you were signing one type of document. The document says something entirely different. Can you simply ask the court to treat your signature as ineffective?
This is where “non est factum” becomes relevant.
WHAT DOES NON EST FACTUM MEAN?
Literally:
“It is not my deed.”
It is a narrow common-law doctrine that may allow a person to avoid liability under a document where they can establish that the document they signed was fundamentally different in character from the document they intended to execute. The doctrine is not designed to rescue someone from a contract simply because they later regret it or discover unfavourable terms.
THE SUPREME COURT HAS SET A HIGH THRESHOLD
In Egbase v. Oriareghan (1985) 2 NWLR (Pt. 5) 322, the Supreme Court emphasised that non est factum must be kept within narrow limits. The Court explained that the doctrine may apply where a person is induced to sign a document that is fundamentally different in character from what they intended to execute. It is not enough to say: “I did not understand everything in the document.” The distinction is fundamental. Mistake about the nature of the document ≠ mistake about its contents.
WHAT DOES NOT USUALLY QUALIFY?
You signed a shareholders' agreement but did not read the drag-along clause.
You signed a loan agreement but misunderstood the interest rate. You signed a five-year agreement believing it was for three years.
You accepted an investment agreement and later discovered terms you considered commercially unattractive.
These are generally mistakes about the contents or legal effect of the document.
They do not, without more, establish non est factum.
WHAT COULD QUALIFY?
The doctrine is concerned with something fundamentally more serious. For example: You believe you are signing a shareholders' agreement. The document you are induced to sign is actually a share transfer instrument. Or you believe you are executing a limited authority, but the document actually creates a substantially different legal instrument. The issue is whether the document executed is essentially different in substance or kind from the transaction you intended. That is the threshold.
AND THERE IS ANOTHER PROBLEM: YOUR OWN CARELESSNESS
A founder cannot simply ignore a document and later rely on non est factum because the terms turned out badly.
In Ezeugo v. Ohanyere (1978) 6–7 SC 171, the Supreme Court held that a person relying on the doctrine must have taken such reasonable precautions as the circumstances required.
A self-induced mistake is insufficient. Nor is non est factum generally available merely because a person misunderstood the legal effect of a document.
SIGNING FIRST AND READING LATER IS A DANGEROUS STRATEGY
Nigerian courts generally attach significant weight to a person's signature.
In Enemchukwu v. Okoye (2016) NGCA 103, the Court of Appeal reiterated the general principle that a person is ordinarily bound by a document they sign, subject to recognised exceptions such as fraud, misrepresentation or non est factum.
So: “I did not read it.” is very different from: “I was induced to execute a fundamentally different document from the one I intended to sign.”
WHY FOUNDERS SHOULD CARE
This matters particularly in transactions involving:
- Investment Agreements
- Shareholders' Agreements
- Share Transfer Documents
- Personal Guarantees
- Loan & Security Documents
- Powers of Attorney
- Corporate Resolutions
The consequences of signing the wrong document can extend to ownership, control, financing, voting rights and personal liability. Non est factum is a narrow safety valve. It is not a substitute for legal due diligence.
THE REAL LESSON
Before signing a significant corporate document, ask: What exactly am I signing? What legal transaction does this document create? What obligations am I assuming? What rights am I giving away? Are there provisions that could materially affect control, ownership or liability? Because once the ink is dry, the question may no longer be: “What did I think I was signing?” It may be: “Can I prove that what I executed was fundamentally different from what I intended?”
THE LEGAL TAKEAWAY “NONESTFACTUM”IS EXCEPTIONALNOTROUTINE.
The doctrine exists to address exceptional cases where genuine consent to the document, in the relevant legal sense, is absent. It does not generally protect a sophisticated party from: failing to read a contract; misunderstanding a clause; making a poor commercial bargain; or regretting the transaction later. The burden of establishing the doctrine is substantial.
CLOSING YOUR SIGNATURE CAN CREATE RIGHTS.
It can also create obligations you never intended to carry. For founders and business leaders, the strongest protection is not relying on non est factum after a dispute arises. It is understanding the document before signing it
