The Federal Rules of Civil Procedure
Dismissal of Actions
(a) Voluntary Dismissal.
(1) By the Plaintiff.
(A) Without a Court Order. Subject to Rules 23(e), 23.1(c), 23.2, and 66 and any applicable federal statute, the plaintiff may dismiss an action without a court order by filing: (i) a notice of dismissal before the opposing party serves either an answer or a motion for summary judgment; or (ii) a stipulation of dismissal signed by all parties who have appeared.
(B) Effect. Unless the notice or stipulation states otherwise, the dismissal is without prejudice. But if the plaintiff previously dismissed any federal- or state-court action based on or including the same claim, a notice of dismissal operates as an adjudication on the merits.
(2) By Court Order; Effect. Except as provided in Rule 41(a)(1), an action may be dismissed at the plaintiff's request only by court order, on terms that the court considers proper. If a defendant has pleaded a counterclaim before being served with the plaintiff's motion to dismiss, the action may be dismissed over the defendant's objection only if the counterclaim can remain pending for independent adjudication. Unless the order states otherwise, a dismissal under this paragraph (2) is without prejudice.
(b) Involuntary Dismissal; Effect. If the plaintiff fails to prosecute or to comply with these rules or a court order, a defendant may move to dismiss the action or any claim against it. Unless the dismissal order states otherwise, a dismissal under this subdivision (b) and any dismissal not under this rule—except one for lack of jurisdiction, improper venue, or failure to join a party under Rule 19—operates as an adjudication on the merits.
(c) Dismissing a Counterclaim, Crossclaim, or Third-Party Claim. This rule applies to a dismissal of any counterclaim, crossclaim, or third-party claim. A claimant's voluntary dismissal under Rule 41(a)(1)(A)(i) must be made:
(1) before a responsive pleading is served; or
(2) if there is no responsive pleading, before evidence is introduced at a hearing or trial.
(d) Costs of a Previously Dismissed Action. If a plaintiff who previously dismissed an action in any court files an action based on or including the same claim against the same defendant, the court:
(1) may order the plaintiff to pay all or part of the costs of that previous action; and
(2) may stay the proceedings until the plaintiff has complied.