To respond to a motion to strike, file a written opposition by your court’s deadline that explains, paragraph by paragraph, why the challenged material belongs in the case. Under Federal Rule of Civil Procedure 12(f), courts can strike content from pleadings that is redundant, immaterial, impertinent, or scandalous, but these motions are generally disfavored, and the moving party carries the burden of showing the material has no possible relation to the controversy and would cause prejudice.{_1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections} That standard works in your favor, but only if you respond on time and tie the challenged material to the actual issues in the case.
Find Your Deadline First
The Federal Rules do not set a single universal deadline for opposing a motion to strike. Rule 6(c)(1) requires the moving party to serve the motion at least 14 days before the scheduled hearing, and any opposing affidavits must be served at least 7 days before the hearing.{_2Legal Information Institute. Federal Rules of Civil Procedure Rule 6 – Computing and Extending Time; Time for Motion Papers} The actual deadline for your opposition brief comes from your court’s local rules. Most federal district courts give the responding party somewhere between 14 and 21 days after the motion is filed and served, though the exact number varies by district.
Check the local rules the day you receive the motion. Missing the deadline is one of the most common and avoidable ways to lose material from your case, because the court can treat the motion as unopposed and grant it. If you need more time, most courts allow a request for an extension for good cause, but the request has to come before the deadline passes.
A few filing points to confirm as you go:
- Most federal courts require electronic filing through CM/ECF. Get access set up before the deadline, not on it.
- Some jurisdictions require a proposed order with your response, spelling out the ruling you want.
- Your opposition must be served on all parties, with proof of service attached.
When computing federal deadlines, the day you receive the motion doesn’t count. Weekends and federal holidays are included in the count unless the total period is less than 11 days.{_2Legal Information Institute. Federal Rules of Civil Procedure Rule 6 – Computing and Extending Time; Time for Motion Papers} If the last day falls on a weekend or holiday, the deadline moves to the next business day.
What Rule 12(f) Actually Reaches
Rule 12(f) lets the court strike two categories from a pleading: insufficient defenses and any matter that is redundant, immaterial, impertinent, or scandalous.{_1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections} It targets specific paragraphs, allegations, or defenses inside a pleading, not the entire complaint or answer. Challenges to the sufficiency of a whole claim belong in a Rule 12(b)(6) motion to dismiss or a Rule 56 summary judgment motion, not here.
Courts approach these motions with skepticism. The general standard is that a motion will be denied unless the challenged language has no possible relation to the controversy and could cause prejudice to the other side. When relevance depends on disputed facts, most courts consider it premature to strike. The pleading gets viewed in the light most favorable to the party who wrote it, so your opposition starts from a position of strength. You still have to articulate why the material matters.
Building the Written Opposition
The written brief is where most motions to strike are won or lost. The judge may never hold a hearing, so treat the brief as if it is your only chance to be heard.
Opening and Legal Standard
Open with a short introduction that identifies what the motion seeks to strike and states your position: the material should remain because it is relevant to the dispute. Then lay out the legal standard. Establish that the movant bears the burden of showing the material has no possible relation to the controversy and would cause prejudice, and that the court views the pleading in the light most favorable to the non-moving party. The disfavored nature of Rule 12(f) motions is the frame the rest of your argument sits inside.
Argument, Paragraph by Paragraph
Address each piece of challenged material individually. For every paragraph or allegation the motion targets, explain its connection to your claims or defenses. The strongest arguments tie the challenged material directly to an element you need to prove or a factual dispute the court will eventually need to resolve. Vague assertions that everything is relevant do not work. Be specific about why each challenged portion matters.
If the motion argues that your material is immaterial or impertinent, show how it provides necessary context or supports a specific legal theory. If the motion calls something scandalous, demonstrate that the allegations are factually grounded and relevant, not included to embarrass. Courts will tolerate uncomfortable facts when they bear on the dispute.
Support your arguments with case law where you can. Federal courts in your district or circuit that have denied similar motions carry the most weight. Attach declarations or affidavits as exhibits if they add factual support for why the challenged material is relevant, such as a declaration explaining the business context behind allegations the opposing party calls immaterial.
Alternatives to a Straight Fight
A direct opposition is not always the strongest play. Depending on what the motion targets, another route may serve you better.
Amend Instead of Fight
If the motion exposes real weaknesses in how you drafted certain allegations, consider amending your pleading rather than defending language you could improve. Under Rule 15(a)(1), you can amend once as a matter of course, without needing permission, within 21 days of serving the original pleading, or within 21 days after a motion under Rule 12(f) is served, whichever comes earlier.{_3Legal Information Institute. Federal Rules of Civil Procedure Rule 15 – Amended and Supplemental Pleadings} An amendment can moot the motion entirely while letting you tighten the pleading and keep the substance of what you originally alleged.
If you have already used the one free amendment, you need the opposing party’s written consent or leave of court. The standard for granting leave is generous: courts should freely give leave when justice so requires.{_4United States Courts. Federal Rules of Civil Procedure (December 1, 2024)} Courts may deny leave if you have already amended multiple times or if the proposed changes would be futile.
Negotiate a Stipulation
Sometimes the efficient path is talking to opposing counsel. If the challenged material includes language that is unnecessarily inflammatory but the underlying facts matter, you might agree to revise specific wording while keeping the substance. That avoids a ruling entirely, saves both sides time, and can build goodwill with the judge who would otherwise have to decide.
Concede What You Can Afford to Lose
Not every allegation is worth defending. If the motion targets material that is genuinely tangential to your core claims, conceding those points focuses the court’s attention on what actually matters. Judges notice when a party fights over everything versus when someone makes strategic choices. Ask yourself honestly: does losing this allegation weaken the case, or does it just feel like giving ground?
If the Court Holds a Hearing
Not every motion to strike gets oral argument. When the court schedules one, use it to address the judge’s specific concerns rather than repeating your brief. Focus on the two or three strongest reasons the material should stay. Judges hearing these motions are usually looking for a quick, concrete explanation of relevance, not a string of case citations.
Be ready for questions about whether you could make your case without the challenged material. The honest answer might be yes, but it provides important context, and that is a legitimate reason to keep it. You do not have to show the material is indispensable, just that it has a real connection to the dispute. If the judge seems inclined to strike something, have a fallback ready, such as agreeing to narrow certain language rather than losing the allegation entirely.
If the Motion Is Frivolous
If the motion was filed to harass, delay the case, or run up your costs, you may be able to seek sanctions under Rule 11, which requires that every motion be supported by existing law or a nonfrivolous argument and not presented for an improper purpose.{_5Legal Information Institute. Federal Rules of Civil Procedure Rule 11 – Signing Pleadings, Motions, and Other Papers; Representations to the Court; Sanctions}
The process has a safeguard many people overlook. You must serve your sanctions motion on the opposing party and then wait 21 days before filing it with the court. During that window, the other side can withdraw or correct the challenged filing and avoid sanctions.{_5Legal Information Institute. Federal Rules of Civil Procedure Rule 11 – Signing Pleadings, Motions, and Other Papers; Representations to the Court; Sanctions} The sanctions motion must be filed separately from your opposition to the motion to strike. The bar is high: a weak motion is not necessarily sanctionable; it has to be without legal or factual basis, or filed for an improper purpose. The same standard applies in reverse, so make sure your own opposition is grounded in good faith and supported by law.
After the Ruling
If the motion is denied, the challenged material stays in your pleading and the case proceeds. If the motion is granted, the stricken material comes out of the record, which may narrow your available arguments or defenses going forward.
A granted motion is not always the end. If you are still within the 21-day window under Rule 15(a)(1), you can amend as a matter of course.{_3Legal Information Institute. Federal Rules of Civil Procedure Rule 15 – Amended and Supplemental Pleadings} Outside that window, you can ask the court for leave to amend. Courts generally grant leave freely when justice requires, though they may deny it if the amendment would be futile, such as re-inserting the same material the court already struck.{_4United States Courts. Federal Rules of Civil Procedure (December 1, 2024)} Fix the deficiency the court identified rather than relitigating the same issue.
Two Boundaries Worth Knowing
This response guidance is for the pleading-stage motion under Rule 12(f). A motion to strike at trial is a different animal: it typically asks the judge to remove testimony or an exhibit from the record on the spot, and opposing counsel objects and the judge rules in seconds rather than days. If you are facing that at trial, the strategy is not the same.
The rules above also come from federal practice. If your case is in state court, the same general principles usually apply, and most states have procedural rules modeled on the federal rules with equivalents to Rule 12(f), but deadlines and specific standards vary. Some states allow broader grounds for striking material; others impose tighter response deadlines; a few handle these challenges through different procedural mechanisms entirely. Read your jurisdiction’s rules of civil procedure and any applicable local court rules before doing anything else. The consequence of missing a deadline is the same everywhere: the court may treat the motion as unopposed.