A motion to strike is a request asking the judge to remove specific material from the court record, either language in a written filing or testimony a witness gave on the stand. The point is to keep improper content from influencing the judge or jury. The motion works differently depending on when it’s used, and the deadlines are unforgiving in both settings.
The Two Settings Where It’s Used
Before anything else, figure out which version of the motion applies, because the procedure and timing are not the same.
In the pretrial phase, the motion targets written court filings called pleadings. These are the documents that frame the lawsuit, such as complaints and answers. Federal Rule of Civil Procedure 12(f) lets a court remove material from a pleading that is redundant, immaterial, impertinent, or scandalous, and it also lets the court strike an entire defense that is legally insufficient.1Cornell Law Institute. Federal Rules of Civil Procedure Rule 12
During trial, the motion targets live testimony. When a witness says something inadmissible, an attorney objects and then asks the judge to strike the answer from the record. This usually comes up when a witness repeats something someone else said out of court (hearsay), speculates about events they didn’t personally observe, gives a rambling answer that doesn’t respond to the question, or offers an expert-level opinion without the qualifications to back it up.
What Counts as Improper in a Pleading
Rule 12(f) spells out the categories, and each one serves a distinct purpose:
- Redundant allegations are repeated unnecessarily and add nothing new.
- Immaterial facts have no connection to the legal dispute. A party’s unrelated personal history inserted to paint them in a bad light would qualify.
- Impertinent assertions don’t respond to any issue the court needs to decide.
- Scandalous content attacks someone’s character or reputation without serving a legitimate legal purpose.
- An insufficient defense is an affirmative defense that fails as a matter of law or doesn’t give the opposing party fair notice of what’s being claimed.1Cornell Law Institute. Federal Rules of Civil Procedure Rule 12
One detail catches people off guard. Under Rule 12(f), the court can strike improper material from a pleading on its own, without either side filing a motion.1Cornell Law Institute. Federal Rules of Civil Procedure Rule 12
How the Motion Is Made
Written Motions Against Pleadings
A written motion to strike is a formal document filed with the court before trial begins. The moving party identifies exactly which portions of the pleading should be removed and provides a legal argument explaining why the material fits one of the Rule 12(f) categories. The opposing side files a written response, and the judge rules on the papers.
Oral Motions During Trial
At trial the motion happens in real time. A witness gives an inadmissible answer, the attorney immediately objects, and if the judge agrees the testimony was improper, the attorney asks the judge to strike it from the record. Speed matters. The objection needs to come right after the problematic answer. Waiting until the next witness or the next day effectively waives the right to challenge that testimony.
Deadlines and Waiver
Timing is one of the easiest ways to lose a motion to strike.
For written pleadings, Rule 12(f) sets a clear window. A party must file the motion either before responding to the pleading or, if no response is required, within 21 days of being served with it.1Cornell Law Institute. Federal Rules of Civil Procedure Rule 12 Miss that window and the court can deny the motion on timeliness alone, regardless of how objectionable the material is. State courts often have their own deadlines that differ from the federal rule.
At trial, the stakes are more immediate. Federal Rule of Evidence 103 requires a party to make a timely objection or motion to strike and state the specific ground for it. Fail to do so, and the right to raise the issue on appeal is gone.2Legal Information Institute (LII). Federal Rules of Evidence Rule 103 – Rulings on Evidence “Timely” here means immediately. If a witness blurts out something inadmissible and the attorney lets it pass, that testimony stays in the record and can influence the verdict.
What Happens After the Judge Rules
If the Motion Is Granted
When a judge grants a motion to strike written material, the portion of the pleading is treated as though it never existed. Neither side can reference it going forward.1Cornell Law Institute. Federal Rules of Civil Procedure Rule 12
When the motion strikes trial testimony, the judge issues a curative instruction telling the jury to disregard what they just heard. The instruction creates the legal fiction that the testimony was never heard, and the jury is bound to follow it.
If the Motion Is Denied
Denial means the material stays. In a trial, the jury can consider the testimony as evidence. In a pleading, the allegations or defenses remain part of the case.
Preserving the Issue for Appeal
Even a denied motion serves a purpose. Under Federal Rule of Evidence 103, you can only claim error in a ruling that admitted evidence if you timely objected or moved to strike on the record and stated the specific ground.2Legal Information Institute (LII). Federal Rules of Evidence Rule 103 – Rulings on Evidence Skip the motion and an appellate court will almost certainly say the argument was waived. A losing motion to strike still protects the ability to challenge the ruling later.
Why Judges Rarely Grant Them
Courts treat motions to strike as a drastic remedy and grant them sparingly. There is a well-established judicial reluctance to remove material from a pleading unless the moving party can show genuine prejudice from leaving it in. Courts also recognize that motions to strike are sometimes filed as a delay tactic. If you’re considering this motion, the material you’re targeting needs to be clearly improper, not just annoying or unflattering, and you should expect the court to lean toward keeping it in.
Courts are more willing to strike an affirmative defense that is plainly insufficient as a matter of law, particularly when the defense has no legal precedent in the context of the case and would only confuse the issues going forward.
How It Differs From a Motion in Limine
These two motions get confused often. A motion in limine asks the judge to rule on whether certain evidence is admissible before it’s ever introduced at trial. It’s preemptive, filed ahead of time so both sides know the ground rules. A motion to strike deals with material that is already in the record, whether in a written filing or through testimony that was already given. An attorney who anticipates a problem files a motion in limine. An attorney surprised by improper testimony moves to strike.
Anti-SLAPP Motions to Strike Are a Separate Thing
In roughly 33 or more states, the phrase “motion to strike” carries a different meaning under anti-SLAPP statutes. SLAPP stands for Strategic Lawsuit Against Public Participation, and these laws protect people from being sued for exercising their free speech rights on matters of public concern. Under an anti-SLAPP statute, a defendant moves to strike the entire lawsuit, not just lines of a pleading.
The procedure flips the usual burden. Once the defendant shows the lawsuit targets speech on a public issue, the plaintiff must demonstrate a reasonable probability of winning the case. If the plaintiff can’t clear that bar, the court dismisses the suit and may order the plaintiff to pay the defendant’s attorney’s fees. If someone mentions a motion to strike in the context of defamation, online reviews, or public advocacy, they are likely talking about this type of motion rather than the federal procedural version.