To respond to an opposing affidavit, you file a counter-affidavit: a sworn written statement, based on your personal knowledge, that contradicts the other side’s version of the facts point by point and puts your own account into the court record. Done properly, it forces the judge to recognize that the facts are genuinely in dispute. Skip it, or file something vague, and the court can accept the opposing affidavit as undisputed and rule against you on the papers.
When a Counter-Affidavit Is the Right Response
The typical trigger is a motion for summary judgment. The moving party attaches one or more affidavits and argues there is no genuine dispute of material fact. Under Federal Rule of Civil Procedure 56, the court must deny that motion if the evidence shows a genuine factual dispute, and your counter-affidavit is the main way to put that dispute on the record.1Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment
Counter-affidavits also show up when you oppose a temporary restraining order, a preliminary injunction, or a motion to dismiss that relies on evidence outside the pleadings. In each of those settings, the goal is the same: your version of the facts, under oath, in the file, before the judge decides.
Know Your Deadline Before Anything Else
There is no single federal deadline for responding to a summary judgment motion. Each district court’s local rules set the window, and it varies. Some districts give 21 days after service, others 28 or more. A scheduling order from the judge overrides the local rule.1Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment
When you count days, exclude the day the motion was served and include the last day of the period. If the last day is a Saturday, Sunday, or federal holiday, the deadline rolls to the next business day. If the clerk’s office is inaccessible on the final day, the deadline moves to the first day it reopens. Service by mail, rather than electronic service, adds three days to your response window.2Legal Information Institute. Federal Rules of Civil Procedure Rule 6 – Computing and Extending Time
Courts regularly refuse to consider late affidavits. Check the local rules the day you learn a motion has been filed, then work backward so you have time to gather documents, draft carefully, and get the signature witnessed if you need one.
Personal Knowledge and Paragraph-by-Paragraph Rebuttal
Every statement in the counter-affidavit has to come from your personal knowledge. Rule 56(c)(4) requires that an affidavit or declaration used to oppose the motion be made on personal knowledge, set out facts that would be admissible at trial, and show that the person signing is competent to testify to them.1Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment Federal Rule of Evidence 602 says the same thing in evidentiary terms: no testimony from someone who lacks firsthand knowledge of the matter.3Legal Information Institute. Federal Rules of Evidence Rule 602 – Need for Personal Knowledge
In practical terms, cut anything that starts with “I was told” or “everyone knew.” That is hearsay or opinion, and a judge will strike it. Write what you did, saw, or heard yourself, with dates, places, and specifics. “I mailed the check on March 3, 2025, and kept the postal receipt showing that date” is the kind of sentence that survives scrutiny.
Work through the opposing affidavit paragraph by paragraph and answer each material claim. If they say the contract was never signed, describe when and where you signed it. If they say delivery was late, lay out the actual delivery timeline. Anything you leave unanswered can be treated as admitted for purposes of the motion, and judges do rely on the small unchallenged points when they decide close cases.
Attaching and Authenticating Exhibits
Documents strengthen a counter-affidavit when they directly contradict something the other side has sworn to: receipts, emails, bank statements, photographs, contracts. Label each one as a numbered or lettered exhibit and reference it in the body of the affidavit at the sentence it supports.
Attaching a document is not the same as authenticating it. Federal Rule of Evidence 901 requires enough proof that the item is what you claim it is.4Legal Information Institute. Federal Rules of Evidence Rule 901 – Authenticating or Identifying Evidence The simplest route is your own sworn statement: in the affidavit, say that Exhibit A is a true and accurate copy of an email you sent on a specific date, and explain how you recognize it. For business records, describe the system that produced them.
The other side can object under Rule 56(c)(2) that your exhibits cannot be presented in admissible form.1Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment Weak authentication is one of the easiest objections for them to win, so spend a sentence or two on the origin of each exhibit and your connection to it.
Format and Caption
Start with the case caption: the court’s name, the parties, and the case number. Federal Rule of Civil Procedure 10 requires this format on pleadings, and courts expect the same on affidavits filed with motions.5Legal Information Institute. Federal Rules of Civil Procedure Rule 10 – Form of Pleadings
Write in the first person and use numbered paragraphs, each focused on a single fact. Where you can, mirror the paragraph numbering of the opposing affidavit so the judge can compare them side by side. Many district courts publish templates on their websites; use the one that matches your local formatting rules.
Signing: Notary or Declaration Under Penalty of Perjury
A traditional affidavit is signed in front of a notary, who verifies your identity, watches you sign, and stamps the document. But federal law offers a shortcut that saves the notary step. Under 28 U.S.C. ยง 1746, you can sign an unsworn declaration under penalty of perjury and it carries the same legal weight as a notarized affidavit.6Office of the Law Revision Counsel. United States Code Title 28 Section 1746 – Unsworn Declarations Under Penalty of Perjury The required language is: “I declare under penalty of perjury that the foregoing is true and correct,” followed by the date and your signature.
Either method works in federal court. If you are filing in state court, check the state rules, because some state proceedings still require notarization.
Whichever method you use, the statements are subject to perjury laws. Knowingly making a false material statement under oath or in a declaration under penalty of perjury is a federal felony punishable by up to five years in prison.7Office of the Law Revision Counsel. United States Code Title 18 Section 1621 – Perjury Generally
Serving the Other Side and Filing With the Court
Once the counter-affidavit is signed, two separate steps follow. You serve a copy on the opposing party (or their attorney) and you file the original with the court.
Service of documents filed after the original complaint is governed by Federal Rule of Civil Procedure 5, not Rule 4. Rule 5 allows you to hand the document to opposing counsel, mail it to their last known address, or send it through the court’s electronic filing system.8Legal Information Institute. Federal Rules of Civil Procedure Rule 5 – Serving and Filing Pleadings and Other Papers If the other party is represented, you serve the lawyer. Electronic service through the court’s e-filing system is now the standard, and service is complete at the moment of filing.
Include a certificate of service stating when, how, and on whom you served the document. Without one, the judge may decline to consider the counter-affidavit at the hearing. Most courts accept a short certificate at the end of the affidavit itself.
Filing usually happens through the district’s electronic filing platform, which requires a searchable PDF. Some clerks still accept paper filings from self-represented litigants. Filing a responsive document like a counter-affidavit in federal court typically does not carry a separate fee, because the case’s initial filing fee covers subsequent filings.
How the Judge Weighs Competing Affidavits
When both sides have sworn to different versions of events, the judge is not deciding who is telling the truth. The question is whether a genuine dispute over a material fact exists. If your counter-affidavit, accepted at face value, contradicts the opposing affidavit on a fact that matters to the outcome, summary judgment must be denied on that issue.1Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment
The opposing side’s usual counter-move is a motion to strike. They can ask the court to disregard paragraphs that are irrelevant, hearsay, conclusory, or scandalous, or object under Rule 56(c)(2) that your supporting materials cannot be presented in admissible form. If the court strikes key paragraphs, what remains may not be enough to create a factual dispute. That is why specificity matters. A counter-affidavit that says “I disagree with the plaintiff’s version” without concrete facts will not survive.
Sanctions for False or Bad-Faith Affidavits
Filing a counter-affidavit you know to be false, or filing one purely to stall, carries consequences beyond perjury exposure. Rule 56(h) lets the court order the offending party to pay the other side’s reasonable expenses, including attorney’s fees, if the affidavit was submitted in bad faith or solely for delay, and the court can hold the party in contempt.1Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment
Rule 11 adds another layer. Signing and filing any paper certifies that the factual claims have evidentiary support and that the filing is not made to harass or delay. Sanctions can include monetary penalties, attorney’s fees to the other side, or non-monetary directives. Rule 11 has a 21-day safe harbor: if you withdraw or correct the challenged paper within 21 days after the opposing party serves a sanctions motion on you, that motion cannot be filed with the court.9Legal Information Institute. Federal Rules of Civil Procedure Rule 11 – Signing Pleadings, Motions, and Other Papers
None of this is a reason to avoid filing. It is a reason to be precise. State what you know from personal experience, attach documentation where you have it, and do not exaggerate. An accurate counter-affidavit that creates a genuine factual dispute is exactly what the rules contemplate.