When looking up whether or not using the phrase “not to my knowledge” be used as a legal defense, I came up with the following.
I appears that the advice Ilhan Omar has been given will only legally protect her for a little while!
The truth of the matter … the one truism in this lifetime is … we all know who our siblings are, especially when we grow up in the same home with them!
In testimony, affidavits, interviews, and potential false-statement or perjury issues:
• If the claim of ignorance is true, the statement is accurate. A true statement about one’s own lack of knowledge cannot support a charge of perjury or a false statement. Perjury generally requires a willful or knowing false statement under oath about a material matter that the speaker does not believe to be true. False-statement statutes (such as 18 U.S.C. § 1001) require a knowingly false statement (or concealment) in a matter within federal jurisdiction. A genuine “not to my knowledge” fails the falsity element.
• If the speaker actually knows the contrary, the phrase is a false statement of their knowledge and can support charges, assuming materiality and the required mental state are proven. Qualifying language does not create a safe harbor for someone who knows the fact.
• Literal-truth principles (from cases like Bronston v. United States) protect answers that are literally true even if evasive or unresponsive in the perjury context; the burden is on the questioner to pin down the answer. However, § 1001 also covers certain concealments, and investigators often view hedging phrases (“not to my knowledge,” “I don’t recall,” etc.) as potential indicators of caution or deception rather than straightforward answers.
• In some state perjury rules (e.g., aspects of California law), making an unqualified assertion about something one does not actually know can itself create issues; qualifying language can help avoid that problem by accurately reflecting the speaker’s limited knowledge.
Courts have also accepted “to my knowledge” language in affidavits as adequate for personal-knowledge requirements in certain procedural contexts (such as summary-judgment affidavits), particularly when the affiant is in a position to know the facts.
Important limits:
• It is not a defense based on ignorance of the law. Mistake or lack of knowledge of a fact can matter where knowledge is an element of an offense or for scienter, but “I didn’t know it was illegal” generally is not.
• It does not prevent cross-examination, credibility challenges, or later evidence showing the speaker did know. Investigators and lawyers often treat it as a hedge that invites follow-up.
• Public statements (e.g., in interviews) are not under oath and do not trigger perjury rules, though statements to federal investigators can implicate § 1001 if material and knowingly false.
In short, the phrase can protect a speaker who is accurately describing limited knowledge (and can limit contractual liability), but it provides no shield if the person in fact knows the opposite.
The truth of the underlying claim of ignorance is decisive. Specific outcomes always turn on the facts, jurisdiction, exact wording, and applicable statute or contract.