Civil Procedure II
A plaintiff can voluntarily dismiss his case without a court order if done before either an answer or summary judgment motion is filed. Rule 41(a)(1)(A). However, most states allow dismissal after a motion to dismiss.
The first voluntary dismissal is without prejudice, but a second dismissal would be with prejudice. Rule 41(a)(1)(B).
A suit can also be dismissed by stipulation by both parties. This is without prejudice unless stipulated otherwise.
If an answer or summary judgment motion has been filed, court approval is needed to dismiss the suit. This is without prejudice unless the court orders otherwise, which it can do. Rule 41(a)(2).
If a plaintiff fails to prosecute by letting a case sit idle, then the defendant may move to involuntarily dismiss the case. Rule 41(b).
A case may also be involuntarily dismissed if the plaintiff does not comply with orders or rules.
An involuntary dismissal normally operates as an adjudication on the merits, dismissing it with prejudice. An exception is if the dismissal is based on lack of jurisdiction, venue, or joinder.