To file a motion to dismiss a civil case in federal court, you draft a written motion identifying which Rule 12(b) grounds apply, file it with the clerk within 21 days of being served with the summons and complaint, serve a copy on every other party, and file a certificate of service confirming you did.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 The mechanics are straightforward. The trap is that defenses you leave out of that first motion are usually waived permanently, so what you include matters as much as how you file it.
The 21-Day Deadline
In federal court, you have 21 days after being served with the summons and complaint to respond, and a motion to dismiss counts as that response. If you waived formal service under Rule 4(d), the window stretches to 60 days from when the waiver request was sent, or 90 days if you were outside the United States when it was sent.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12
Filing the motion pauses your obligation to file a formal answer. If the court later denies it, you have 14 days from the court’s notice to serve your answer.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12
State courts run on their own timetables. Some give 30 days, some use other schedules, and local filing rules differ from federal practice. Check the rules of the specific court where the case is pending before you calendar anything.
Choose Your Grounds
Rule 12(b) lists seven defenses a defendant can raise by motion before filing an answer, and most state rules mirror them closely. You can raise more than one in a single motion, and generally you should.
- Lack of subject matter jurisdiction — the court has no authority over this type of dispute. A state family court cannot hear a federal patent case. This is the one defense that can never be waived; the court can raise it on its own at any stage.2Legal Information Institute. Subject Matter Jurisdiction
- Lack of personal jurisdiction — the court has no authority over you, usually because you lack sufficient ties to the state where the case was filed.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12
- Improper venue — the case was filed in the wrong geographic location. A successful challenge usually results in a transfer rather than an outright dismissal.
- Insufficient process — the summons or complaint has a formal defect, such as a wrong name or missing information.
- Insufficient service of process — the documents were fine, but they were not delivered to you the way the rules require.
- Failure to state a claim — even if every fact the plaintiff alleges is true, the complaint does not describe conduct the law provides a remedy for. This is the most common and most powerful ground.
- Failure to join a required party — someone whose rights would be directly affected was left out, and the case cannot proceed fairly without them.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12
Raise Every Available Defense at Once
This is where defendants make their most expensive mistakes. Four of the seven defenses — personal jurisdiction, improper venue, insufficient process, and insufficient service of process — are permanently waived if you do not raise them in your first Rule 12 filing. A party who files a Rule 12 motion cannot come back later with a second motion raising a defense that was available but omitted.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12
Bundle every available Rule 12(b) defense into a single motion. If you are unsure whether a defense applies, include it. Dropping a weak argument later costs nothing; failing to raise a valid one costs you that defense forever.
Three defenses survive the consolidation rule. Subject matter jurisdiction can be raised at any time. Failure to state a claim and failure to join a required party can be raised as late as trial, though waiting that long is rarely strategic.
Draft the Motion
A motion to dismiss is a formal court filing, and courts are particular about format. Start with a caption identifying the court, the case number, and the parties.3Legal Information Institute. Federal Rules of Civil Procedure Rule 10 – Form of Pleadings A title such as “Defendant’s Motion to Dismiss” appears below the caption.
The body should do three things clearly. First, identify the grounds. Cite the specific subsection — “failure to state a claim under Rule 12(b)(6)” — so the judge knows exactly what standard to apply. Second, lay out the relevant facts. For a personal jurisdiction challenge, explain your lack of connection to the forum state. For failure to state a claim, walk the court through the complaint’s deficiencies. Third, make the legal argument. Cite the statutes, rules, and cases supporting dismissal. This usually goes into a supporting memorandum, sometimes called a brief or a memorandum of points and authorities, which many courts require as a separate document. Local rules will tell you.
End with a request for relief stating exactly what you want the court to do: dismiss the entire case, dismiss specific claims, or dismiss specific parties. The attorney or self-represented party signs the filing, and a certificate of service confirming you delivered copies to all other parties is required.
Do Not Attach Outside Evidence
If you attach exhibits, affidavits, or other materials beyond the complaint and its attachments to a Rule 12(b)(6) motion, the court may convert it into a motion for summary judgment. When that happens, the court must give all parties a reasonable opportunity to present additional evidence, and the entire proceeding shifts to a different and more demanding standard.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 Stick to the face of the complaint. If you need outside evidence to make your case, you probably want a summary judgment motion from the start, not a motion to dismiss that accidentally becomes one.
File and Serve the Motion
File the motion with the clerk of the court where the case is pending. Most federal courts require electronic filing through the CM/ECF system, and many state courts have adopted similar e-filing platforms. In courts that still accept paper filings, bring multiple copies: one for the court and one for each opposing party.
In federal court, motions filed after the complaint generally do not require a separate filing fee, because the initial case filing fee covers subsequent filings. State practices vary, so check the local fee schedule.
After filing, serve the motion on every other party. Serve the attorney rather than the party directly when a party is represented. Under federal rules, acceptable service methods for post-complaint filings include hand delivery, mailing to the person’s last known address, and electronic transmission if the recipient is a registered user of the court’s e-filing system or has otherwise consented in writing.4Legal Information Institute. Federal Rules of Civil Procedure Rule 5 A written motion and notice of any hearing must be served at least 14 days before the hearing date, unless the court orders otherwise.5Legal Information Institute. Federal Rules of Civil Procedure Rule 6
File a certificate of service with the court confirming when and how you delivered copies to the other parties. Without it, the court may not act on your motion.
What Happens After You File
The plaintiff typically files an opposition brief arguing why the case should survive. Local rules set the deadline; in many federal districts it is 14 to 21 days after service of the motion. You may then file a reply addressing the plaintiff’s arguments. Some courts decide motions to dismiss on the papers alone; others schedule oral argument, especially for complex or close cases.
The judge has three basic options. The court can grant the motion entirely and dismiss the whole case, grant it in part so some claims survive, or deny it, in which case you must file your answer within 14 days of the order.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12
With Prejudice vs. Without Prejudice
A dismissal “with prejudice” is a final judgment on the merits, and the plaintiff cannot refile the same claim. Under federal rules, most involuntary dismissals operate as adjudications on the merits unless the court says otherwise, with three exceptions: dismissals for lack of jurisdiction, improper venue, or failure to join a required party do not count as merits rulings.6Legal Information Institute. Federal Rules of Civil Procedure Rule 41 A dismissal “without prejudice” leaves the door open for the plaintiff to fix the deficiencies and refile. Courts often dismiss without prejudice on a first 12(b)(6) motion, giving the plaintiff a chance to amend before closing the case for good.
The Plaintiff Can Amend
After you serve a motion to dismiss, the plaintiff can amend the complaint once as a matter of course within 21 days, without asking the court’s permission. An amended complaint can moot your motion, forcing you to start over against the new allegations. Even beyond that 21-day window, courts are instructed to “freely give leave” to amend “when justice so requires.”7Legal Information Institute. Federal Rules of Civil Procedure Rule 15 A granted motion to dismiss often results in the plaintiff getting another shot rather than the case ending.
Discovery Does Not Automatically Pause
Filing a motion to dismiss does not freeze the rest of the case. Federal rules do not automatically stay discovery while the motion is pending. If you want discovery paused, file a separate motion for a protective order showing good cause. Some judges grant these routinely when a strong jurisdictional challenge is pending; others expect the case to keep moving. Do not assume your motion buys you time on discovery deadlines unless the court explicitly says so.
Sanctions for Frivolous Motions
By signing and filing any motion, an attorney or self-represented party certifies that it is not filed to harass or cause unnecessary delay and that the legal arguments are supported by existing law or by a reasonable argument for changing the law.8Legal Information Institute. Federal Rules of Civil Procedure Rule 11
A court that finds a motion violates these standards can impose sanctions ranging from nonmonetary directives to an order paying the other side’s attorney’s fees resulting from the violation. A law firm is jointly responsible for violations by its attorneys absent exceptional circumstances. There is a built-in safety valve: before filing a sanctions motion, the opposing party must serve it on you first, and you have 21 days to withdraw or correct the challenged filing before it reaches the court.8Legal Information Institute. Federal Rules of Civil Procedure Rule 11 Sanctions are rare for good-faith arguments that simply do not prevail. A motion filed purely for delay or with no colorable legal theory is a different matter.