Affidavit Meaning and How It Works in Federal Court

This article is provided for educational and informational purposes only. It does not constitute legal, financial, or tax advice, and no attorney-client relationship is formed by reading it. Laws, regulations, official guidance, and related information vary by jurisdiction, change frequently, and may have changed or become outdated since the publication date. Always verify current information with authoritative sources and consult a qualified professional about your specific circumstances. The author and publisher assume no liability for actions taken based on this information.

Contents

An affidavit is a sworn written statement
A federal declaration can often replace an affidavit
Federal courts use affidavits to decide some motions
An oath does not settle admissibility
Federal law attaches consequences to material falsehoods
Sources

Key Facts

Federal level: An affidavit is a written factual statement sworn before a notary or court officer.
Federal level: Under 28 U.S.C. § 1746, a dated and signed unsworn declaration made under penalty of perjury can substitute for an affidavit when a federal authority permits or requires the sworn writing, subject to the statute’s exceptions.
Federal level: Federal Rule of Civil Procedure 56 requires a summary-judgment affidavit or declaration to rest on personal knowledge, set out facts that would be admissible in evidence, and show that the writer is competent to testify.
Federal level: An affidavit offered for the truth of its assertions can raise hearsay questions because the Federal Rules of Evidence define a written assertion as a statement.
Federal level: Federal perjury law reaches specified willfully or knowingly false material statements made under an authorized oath or in a qualifying declaration under penalty of perjury.

An affidavit is a sworn written statement

An affidavit is a written statement in which a person asserts facts as true under oath before a notary or court officer.

A federal declaration can often replace an affidavit

Federal law sometimes allows an unsworn declaration to perform the same function as an affidavit. Under 28 U.S.C. § 1746, when a federal law, rule, regulation, order, or requirement permits or requires a written sworn statement or affidavit, a written declaration can have like force and effect if it is signed as true under penalty of perjury and dated.

Section 1746 provides separate forms for a declaration executed inside the United States and one executed outside the United States. The outside-the-United-States form includes the phrase “under the laws of the United States of America.” The statute excludes depositions, oaths of office, and oaths that must be taken before a specified official other than a notary public.

This distinction explains why “affidavit” and “declaration” are not always interchangeable labels even when federal law gives the two writings the same effect. The authority requiring the statement determines whether § 1746 applies.

Federal courts use affidavits to decide some motions

Federal Rule of Civil Procedure 43(c) allows a court deciding a motion based on facts outside the record to hear the matter on affidavits, oral testimony, or depositions. Rule 43(a), by contrast, generally requires trial witness testimony to be taken in open court unless another listed federal authority provides otherwise.

Summary judgment has a more specific safeguard. Rule 56(c)(4) requires an affidavit or declaration supporting or opposing a summary-judgment motion to be made on personal knowledge, set out facts that would be admissible in evidence, and show that the affiant or declarant is competent to testify about those matters.

Rule 56(h) also addresses an affidavit or declaration submitted in bad faith or solely for delay. After notice and a reasonable opportunity to respond, the court may order the submitting party to pay the other party’s reasonable expenses, including attorney’s fees, and may hold an offending party or attorney in contempt.

An oath does not settle admissibility

The Federal Rules of Evidence still matter when an affidavit is offered as proof. Rule 602 generally requires evidence sufficient to support a finding that a witness has personal knowledge of the matter, and the rule permits the witness’s own testimony to supply that evidence.

Hearsay is a separate question. Rule 801 defines a statement to include a written assertion and defines hearsay as a statement made outside the current trial or hearing that a party offers to prove the truth of what it asserts. Rule 802 bars hearsay unless a federal statute, the Federal Rules of Evidence, other Supreme Court-prescribed rules, or another rule identified in Rule 802 provides otherwise.

As a result, the fact that a writing was sworn does not itself resolve whether its assertions may be used for their truth. The applicable procedural and evidence rules determine the affidavit’s permissible use.

Federal law attaches consequences to material falsehoods

Under 18 U.S.C. § 1621, federal perjury includes willfully stating or subscribing a material matter the person does not believe true after taking an oath authorized by federal law. The same section also covers a person who willfully subscribes a materially false statement under penalty of perjury as permitted by § 1746.

Section 1623 addresses knowingly false material declarations in proceedings before or ancillary to a federal court or grand jury. These statutes require more than an inaccurate detail: their text requires the specified mental state and materiality.