The difference between a demurrer and a motion to dismiss comes down to which court you’re in and how much ground the challenge covers. Federal courts abolished the demurrer in 1938 and replaced it with the motion to dismiss under Rule 12(b), which lists seven distinct defenses. A handful of states, most prominently California, still use demurrers, and those are narrower in scope. Federal advisory notes describe a Rule 12(b)(6) motion as “substantially the same as the old demurrer,” but the procedural differences matter if you’re on either side of one.1Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Notes of Advisory Committee on Rules 1946 Amendment
Which One Applies to Your Case
The split is straightforward. Federal courts use motions to dismiss. Certain state courts use demurrers. When the Federal Rules of Civil Procedure took effect in 1938, Rule 7(c) expressly abolished “demurrers, pleas, and exceptions for insufficiency of a pleading.”2Office of the Law Revision Counsel. Federal Rules of Civil Procedure Rule 7 – Pleadings Allowed; Form of Motions Everything a demurrer used to do in federal court moved into Rule 12(b).
States chose for themselves. California’s code of civil procedure contains detailed demurrer provisions, and a few other states retain variations. Most states adopted procedural rules modeled on the federal system and use motions to dismiss instead. If you’re in federal court, you will never file a demurrer. If you’re in a demurrer state, that filing may be your only route to challenge the legal sufficiency of a complaint before you have to answer it.
What Each One Can Challenge
A demurrer makes a single kind of argument: even if every fact in the complaint is true, the plaintiff still has no valid legal claim. It doesn’t dispute what happened. It disputes whether what happened matters under the law. A plaintiff might describe a situation in vivid detail, but if those facts don’t add up to a recognized cause of action, a demurrer says the case should end there.
Demurrer states typically recognize two kinds. A general demurrer attacks the complaint’s fundamental legal validity, arguing the plaintiff failed to state facts that would support any recognized claim. A special demurrer targets narrower defects, like a complaint so vague the defendant can’t reasonably respond. Common grounds include complaints that skip essential elements (alleging breach of contract without identifying the contract), claims barred by the statute of limitations, and pleadings too uncertain to put the defendant on notice.
A federal motion to dismiss covers much more ground. Rule 12(b) lists seven distinct defenses, only one of which overlaps with the demurrer’s function:3Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – How to Present Defenses
- Lack of subject-matter jurisdiction — the court has no authority over this type of case.
- Lack of personal jurisdiction — the court has no authority over this particular defendant.
- Improper venue — the case was filed in the wrong district.
- Insufficient process — the summons or complaint itself was defective.
- Insufficient service of process — the papers weren’t delivered properly.
- Failure to state a claim — even taking the complaint at face value, it doesn’t describe a viable legal theory.
- Failure to join a required party — someone who needs to be in the lawsuit wasn’t included.
Only the sixth ground, failure to state a claim, does the same work as a demurrer. The other six address procedural problems that exist in state courts too but are raised through separate motions there, not through the demurrer.
For the failure-to-state-a-claim ground, two Supreme Court decisions shape how federal judges evaluate a Rule 12(b)(6) motion. Bell Atlantic Corp. v. Twombly held that a complaint needs “enough factual matter (taken as true) to suggest” a plausible claim.4Justia Law. Bell Atlantic Corp. v. Twombly, 550 U.S. 544 (2007) Ashcroft v. Iqbal confirmed that this plausibility standard applies to all civil cases and instructed courts to disregard allegations that merely restate legal conclusions.5Justia Law. Ashcroft v. Iqbal, 556 U.S. 662 (2009) Bare-bones, conclusory complaints don’t survive in federal court, and this is where most 12(b)(6) motions are won or lost.
Deadlines and Filing Requirements
In federal court, a defendant has 21 days after being served to respond, either by filing an answer or a Rule 12 motion.6United States Courts. Federal Rules of Civil Procedure – December 1, 2024 Waiver of formal service under Rule 4(d) extends the deadline to 60 days, or 90 days for defendants outside the United States. Filing a Rule 12 motion pauses the clock on the answer. If the court denies the motion, the defendant gets 14 days from notice of that ruling to answer.7Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Effect of a Motion
State demurrer deadlines vary but typically fall around 30 days after service. Many demurrer states require the defendant to meet and confer with the plaintiff’s attorney before filing, either in person or by phone, to try to resolve the deficiencies without court involvement. If that fails, the demurrer proceeds with a declaration documenting the effort.
Both devices require a written memorandum with legal argument and citations. After filing, the court typically schedules a hearing.
What the Judge Looks At
A demurrer tests the complaint on its face. The judge reads the complaint, accepts the factual allegations as true, and decides whether those facts add up to a valid legal claim. Courts can take judicial notice of undisputable facts like public records and other court filings, but they generally can’t look at outside evidence such as depositions or contracts that weren’t attached to the complaint. If you want to challenge the facts rather than the legal theory, the demurrer isn’t the tool for the job.
A federal motion to dismiss under Rule 12(b)(6) starts from the same premise: the court accepts the factual allegations as true and asks whether they plead a plausible claim. But federal practice has a wrinkle. If either side presents material outside the complaint, the court can convert the motion into one for summary judgment under Rule 56, giving both sides a chance to present relevant evidence.8Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Result of Presenting Matters Outside the Pleadings The demurrer has no equivalent conversion mechanism.
For the other six Rule 12(b) grounds, evidence outside the complaint is routine. A challenge to personal jurisdiction, for instance, usually involves declarations about the defendant’s contacts with the forum state. That evidentiary flexibility is built into the motion to dismiss framework in a way the demurrer doesn’t accommodate.
The Waiver Trap in Federal Court
Federal rules impose a “use it or lose it” requirement on certain defenses, and this is the trap that catches unprepared defendants. If you file a Rule 12 motion but leave out a defense based on personal jurisdiction, improper venue, insufficient process, or insufficient service of process, that defense is waived permanently.9Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Waiving and Preserving Certain Defenses You cannot raise it later in an answer or a second motion.
Two defenses escape the waiver rule. Failure to state a claim can be raised at any point, including in a later motion, in the answer, or at trial. Lack of subject-matter jurisdiction can never be waived; a court can and must dismiss the case whenever it realizes it lacks subject-matter jurisdiction, even on appeal.9Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Waiving and Preserving Certain Defenses
The practical lesson: if you’re filing a motion to dismiss in federal court, include every applicable defense in your first motion. Holding back a venue or jurisdiction argument for strategic reasons can backfire badly. Demurrer practice doesn’t follow this consolidation rule in the same way, but defendants in demurrer states face their own procedural traps around timing and scope that vary by jurisdiction.
What Happens If the Motion Is Granted
When a court grants either a demurrer or a motion to dismiss, the next question is whether the dismissal is “with prejudice” or “without prejudice.” That distinction decides whether the case is truly over.
A dismissal without prejudice lets the plaintiff try again. The case is closed for now, but the plaintiff can fix the problems and refile, typically within the time remaining under the statute of limitations. In federal court, most voluntary dismissals and many court-ordered dismissals default to “without prejudice” unless the order says otherwise.10Legal Information Institute. Federal Rules of Civil Procedure Rule 41 – Dismissal of Actions
A dismissal with prejudice is permanent. The plaintiff cannot refile the same claim against the same defendant. Under the federal rules, an involuntary dismissal operates as a judgment on the merits unless the court says otherwise or the dismissal was for lack of jurisdiction, improper venue, or failure to join a required party.10Legal Information Institute. Federal Rules of Civil Procedure Rule 41 – Dismissal of Actions
In demurrer practice, a court that sustains a demurrer typically gives the plaintiff “leave to amend,” meaning a chance to fix the complaint and try again. A demurrer sustained without leave to amend is essentially a dismissal with prejudice and ends the case. Courts usually reserve that outcome for defects that can’t be cured no matter how the plaintiff rewrites the complaint.
Both systems give plaintiffs a path to amend. In federal court, a plaintiff can amend the complaint once “as a matter of course” within 21 days after a motion to dismiss is served, without asking the court’s permission.11Legal Information Institute. Federal Rules of Civil Procedure Rule 15 – Amended and Supplemental Pleadings After that window closes, the plaintiff needs the opposing party’s consent or the court’s leave, which courts are directed to grant “freely” when justice requires. In demurrer states, the court decides at the time it sustains the demurrer whether to grant leave to amend, and it usually does unless the defect is fundamental.
Strategic Consequences
For defendants, both devices serve the same core purpose: ending a case early without the expense of discovery, depositions, and trial. Even an unsuccessful motion provides useful information about how the judge views the claims and where the plaintiff’s case is vulnerable.
For plaintiffs, surviving one of these challenges is a real milestone. A denied motion to dismiss tells both sides that the court believes the complaint states a plausible claim, and that often shifts settlement dynamics. Defendants who expected an early exit face the cost and risk of full litigation, and that recalculation can bring people to the negotiating table.
One strategic difference is worth flagging. Because a federal motion to dismiss can raise jurisdictional and procedural defenses alongside substantive ones, defendants can attack a case on multiple fronts in a single filing. A demurrer is narrower, so a defendant in a demurrer state may need to file separate motions to challenge jurisdiction or service. The federal motion bundles everything together, but that consolidation carries the waiver risk described above. Miss a defense in your first Rule 12 motion, and it’s gone.
Filing a motion to dismiss also doesn’t automatically pause discovery in federal court. Unless the judge grants a discretionary stay, documents and depositions may still be moving while the motion is pending, so a motion to dismiss isn’t reliably a delay tactic.