To write a motion to dismiss, identify which Rule 12(b) ground fits your case, raise every applicable waivable defense in that same filing, and present the argument in a formatted document with a caption, short introduction, memorandum of points and authorities, signature block, and certificate of service, all filed before your answer is due. The document is formal, the deadlines are tight, and a few of the available defenses vanish if you leave them out of this first response.
Pick the Ground That Fits
Rule 12(b) of the Federal Rules of Civil Procedure lists seven grounds for dismissal. Before drafting, decide which one (or more) you’re invoking, because the standard, the proof, and the attachments all change with the ground.
Lack of subject-matter jurisdiction. The court has no authority over the type of case. Federal courts hear federal-question cases or diversity cases where the amount in controversy exceeds $75,000. This defense is never waived and can be raised at any time, including by the court on its own.
Lack of personal jurisdiction. The court has no authority over the defendant. Under International Shoe Co. v. Washington (1945), a court can reach an out-of-state defendant only when that defendant has “minimum contacts” with the forum such that suit there does not offend “traditional notions of fair play and substantial justice.”
Improper venue. Even where jurisdiction exists, the case may be in the wrong district. The court can dismiss or transfer to a proper district.
Insufficient process and insufficient service of process. The first attacks a defect in the summons or complaint itself; the second attacks how those papers were delivered. Mullane v. Central Hanover Bank & Trust Co. (1950) requires notice “reasonably calculated” to inform a party of the action.
Failure to state a claim. The most common ground, filed under Rule 12(b)(6). The argument is that even if every factual allegation in the complaint is true, no viable legal claim is described. Bell Atlantic Corp. v. Twombly (2007) established a “plausibility” standard: factual allegations must raise the right to relief “above the speculative level.” Ashcroft v. Iqbal (2009) added a two-step analysis — the court sets aside conclusory statements, then asks whether the remaining facts plausibly suggest liability. A “formulaic recitation of the elements” is not enough.
Failure to join a required party. Under Rule 19, some parties are indispensable; if one can’t be joined, the case may be dismissed rather than decided in that party’s absence.
The statute of limitations is not a separate Rule 12(b) ground, but you can raise it inside a 12(b)(6) motion when the complaint itself shows the claim was filed too late. If you need outside evidence to prove the time bar, that argument belongs later in the case.
Raise Every Waivable Defense in This Motion
Rule 12(h) is where drafters get burned. Personal jurisdiction, improper venue, insufficient process, and insufficient service of process are all waived if you don’t raise them in your first response to the lawsuit. File a motion to dismiss on one ground and forget the venue objection, and the venue defense is gone for good. You can’t resurrect it in an amended motion or in your answer.
Failure to state a claim and failure to join a required party are more forgiving. You can press them later in a responsive pleading, in a motion for judgment on the pleadings, or at trial. Subject-matter jurisdiction stands apart entirely — never waived, raisable at any time, and the court has an independent duty to dismiss when it finds jurisdiction lacking.
The practical rule when drafting: if you have even a colorable argument on personal jurisdiction, venue, process, or service, put it in this motion. There is no second chance.
Build the Document
A motion to dismiss is a formal filing with components the court expects to see in a predictable order. Local rules add variation, but the core is consistent across federal district courts.
Caption and Title
Start with the caption: court, parties, case number, and document title. The caption should match the complaint exactly. Below it, title the document precisely — for example, “Defendant’s Motion to Dismiss Pursuant to Federal Rule of Civil Procedure 12(b)(6)” — so the judge knows at a glance what you’re filing and under which ground.
Introduction
Open with a short paragraph identifying who you are, what you want, and why. Half a page or less. A judge working through a stack of motions needs the dispute and your position within seconds.
Memorandum of Points and Authorities
This is the body of the motion. State the legal standard the court applies — for a 12(b)(6) motion, the Twombly/Iqbal plausibility standard — and then walk the judge through exactly how the complaint fails that standard. Quote the complaint’s own paragraphs. Explain their defects. Every legal assertion needs a citation to a binding statute or case.
Federal district courts impose page limits on these memoranda. Twenty to twenty-five pages is a common ceiling for the moving brief, with shorter limits for oppositions and replies. Check your court’s local rules first; exceeding the limit can get the motion rejected.
Declarations and Exhibits (With Care)
If your motion raises factual issues like personal jurisdiction or defective service, you may need to attach declarations or affidavits that establish those facts. On a 12(b)(6) motion, however, be careful. The court looks only at the complaint and documents it references or attaches. Submitting outside evidence can trigger Rule 12(d), converting the motion to one for summary judgment under Rule 56. Conversion changes the standard and gives both sides a new round of evidence. If that isn’t what you want, keep outside material out of a 12(b)(6) motion.
Conclusion and Proposed Order
End with a brief conclusion restating what you want the court to do. Many judges want or require a proposed order they can sign if the motion is granted. The proposed order should state whether you’re asking for dismissal with or without prejudice.
Signature Block
Rule 11 requires that every motion be signed by at least one attorney of record, or by the party personally if unrepresented. The signature must include address, email, and telephone number. By signing, you certify that the legal arguments are warranted, the factual contentions have evidentiary support, and the motion is not filed for an improper purpose. An unsigned motion must be stricken unless corrected promptly.
Certificate of Service
Rule 5 requires that every written motion be served on all parties. Most courts expect a certificate of service confirming you did so. In federal court, service generally happens through the electronic filing system, which notifies registered users automatically.
What the Court Will Actually Read
On a 12(b)(6) motion, the court applies the “four corners” rule. It evaluates the complaint, documents attached to the complaint, and documents incorporated by reference. All well-pleaded factual allegations are taken as true, and reasonable inferences go to the plaintiff. The question isn’t whether the plaintiff will win; it’s whether the complaint describes a plausible claim.
There is an exception for documents referenced in the complaint and central to the claim, even when not physically attached. A breach-of-contract complaint, for example, lets the court consider the contract itself. Knowing this exception helps you decide what to attach and what to reference. Push beyond it and you risk Rule 12(d) conversion.
Deadlines and Local Rules
A well-written motion filed late or in the wrong format is worthless.
In federal court, a defendant generally has 21 days after service of the summons and complaint to respond. The motion to dismiss must be filed before the answer. Filing it pauses the answer deadline; if the court denies the motion, the defendant has 14 days after notice of the ruling to answer.
Many local rules also require a meet-and-confer before filing. The moving party contacts the opposing side to try to resolve the dispute informally, and often must file a statement certifying that effort. Skip it and the court may refuse to consider the motion.
Local rules also set font size, margins, line spacing, and page limits. These details matter more than drafters expect. Courts routinely reject filings for formatting defects, and refiling eats time you may not have. Pull the local rules for your specific court before you write a word; many federal district courts post them online with sample documents and checklists.
After You File
Filing is the opening move. What follows is a structured exchange.
The opposing party gets a set number of days to file an opposition brief — commonly 14 to 21 days in federal district courts. The moving party can then file a reply, usually within 7 to 14 days, subject to shorter page limits. Some courts decide motions on the papers. Others set oral argument, particularly for dispositive motions. If a hearing is set, prepare for questions about the weakest points in your motion, because that’s where judges focus.
Keep the Motion Defensible Under Rule 11
Rule 11 puts teeth behind the signature. If a court determines a motion was filed for an improper purpose, that its legal contentions are frivolous, or that its factual assertions lack evidentiary support, it can impose sanctions. Those sanctions may include an order to pay the opposing side’s attorney’s fees, a monetary penalty paid to the court, or nonmonetary directives, limited to what’s necessary to deter the conduct.
Before seeking sanctions, the opposing party must serve the Rule 11 motion and wait 21 days, giving you a chance to withdraw the filing. That safe harbor means sanctions rarely arrive by surprise, but the risk is a reminder: every argument in the motion should rest on a good-faith reading of the law and the facts actually in the record.