A motion to strike under Federal Rule of Civil Procedure 12(f) asks a federal judge to remove specific language from an opponent’s pleading — an insufficient defense, or material that is redundant, immaterial, impertinent, or scandalous. It targets pieces of a filing, not the whole case, and the deadline to file is short: before you respond to the pleading, or within 21 days of service if no response is required.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections
What Rule 12(f) Lets a Judge Strike
Rule 12(f) sets out five categories of material a court can remove from a pleading:
- An insufficient defense — one that fails to present a valid legal basis even if every fact alleged were true.
- Redundant material — facts or arguments restated elsewhere in the same document.
- Immaterial allegations — claims with no real bearing on the legal dispute.
- Impertinent statements — assertions that don’t connect to any claim or defense in the case.
- Scandalous matter — language that attacks someone’s character or includes offensive allegations that serve no litigation purpose.
The court can strike this material on its own or after a party moves. Nothing else falls within the rule. If the problem with the pleading is that it fails to describe a legal wrong at all, that is a Rule 12(b)(6) motion to dismiss, not a motion to strike.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections
When You Have to File
A party who wants to move must do so before responding to the pleading, or within 21 days of being served if no response is required.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections Missing that window doesn’t necessarily kill the motion, because the court keeps discretion to act on its own initiative. But a late motion faces an uphill battle, and relying on the judge to notice and act sua sponte is not a plan.
Why Most Motions to Strike Lose
Federal courts treat these motions with skepticism. The working standard is that a motion will be denied unless the challenged language has no possible connection to the dispute and could prejudice the opposing party. Judges read the pleading in the light most favorable to the person who wrote it, much like the standard applied on a motion to dismiss. Over-pleading — including more detail than strictly necessary — usually is not enough to get material stricken.
The one area where courts relax the standard is truly scandalous allegations. When a pleading contains language designed to embarrass, degrade, or inflame rather than advance a legal argument, judges are more willing to cut it. Outside that context, the moving party carries a heavy burden. Filing a motion to strike as a tactical delay, which happens more often than courts would like, can backfire and cost you credibility with the judge.
Before drafting, ask a plain question about the material you want removed: does it prejudice you if it stays in, or is it just annoying? If it is just annoying, the motion is not worth filing.
How to Draft the Motion
Precision is everything. Identify the exact location of the objectionable content — page numbers, paragraph numbers, and line numbers where possible. Vague requests to “strike the improper allegations” without pinpointing them are a good way to get the motion denied. The filing needs a standard caption listing the court name, the parties, and the case number.
The core of the motion is the legal memorandum, sometimes called a memorandum of points and authorities. This is where you explain why the targeted material qualifies as redundant, immaterial, impertinent, scandalous, or an insufficient defense under Rule 12(f), citing the rule and any relevant case law. Close with a prayer for relief that spells out exactly what you want the judge to do: strike specific paragraphs, strike an entire defense, or whatever the request may be.
Many federal courts provide standardized forms on their local websites. Check local rules before filing. Formatting requirements, page limits, and briefing schedules vary by district, and a motion that ignores them can be rejected before the judge ever reads the substance.
Serving and Hearing the Motion
In most federal courts, motions are filed electronically through the CM/ECF system, which automatically notifies registered parties. If the opposing party is not registered for electronic service, arrange service another way, such as mailing a copy to their last known address.
Under the Federal Rules, a written motion and notice of hearing must be served at least 14 days before the hearing date, and any opposing affidavit must be served at least 7 days before the hearing.2Legal Information Institute. Federal Rules of Civil Procedure Rule 6 – Computing and Extending Time Local rules typically add their own requirements for opposition briefs and reply papers, so the practical timeline varies by district. Some judges decide the motion on the papers without a hearing. Others schedule oral argument, particularly when the scandalous-matter standard is at issue or when the motion could narrow the case significantly. The process ends when the judge issues a written order granting or denying the motion, which becomes part of the official case record.
What Happens After the Motion Is Filed
Winning does not always end the fight. Under Rule 15, a party whose pleading has been targeted by a motion to strike has the right to amend once as a matter of course, without needing the court’s permission, if the amendment is filed within 21 days after the motion was served.3Legal Information Institute. Federal Rules of Civil Procedure Rule 15 – Amended and Supplemental Pleadings That deadline is designed to push the filer to rethink the problematic language quickly and can moot your motion altogether if they clean up the pleading on their own.
After that 21-day window closes, amendment requires either the opposing party’s written consent or the court’s permission. The standard for leave to amend is generous: courts are instructed to grant it freely “when justice so requires.”3Legal Information Institute. Federal Rules of Civil Procedure Rule 15 – Amended and Supplemental Pleadings A party who had material stricken as scandalous and then tries to reinsert essentially the same language is unlikely to get a warm reception.
Rule 12(f) Is Not the Only Way a Pleading Gets Stricken
If your goal is to end the case rather than trim a filing, Rule 12(f) is the wrong tool. A motion to dismiss under Rule 12(b)(6) argues that the entire complaint, taken at face value, doesn’t describe a legal wrong the court can fix. A successful motion to dismiss can end an entire case; a successful motion to strike usually just trims the filing.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections
There is also a separate power to strike pleadings as a sanction. Rule 37 lets a judge strike part or all of a party’s pleading when that party defies a court order to participate in discovery — refusing to produce documents, sit for a deposition, or answer interrogatories.4Legal Information Institute. Federal Rules of Civil Procedure Rule 37 – Failure to Make Disclosures or to Cooperate in Discovery When a defendant’s answer is stricken as a Rule 37 sanction, the practical result is often a default judgment, because the defendant no longer has a valid pleading in the case. That is a different motion, a different standard, and a different set of consequences from a Rule 12(f) motion, and the two should not be confused when you are drafting.