Because an opening statement to the jury in a civil case is supposed to lay out what the plaintiff intends to prove, it is often said that the failure of counsel to refer in his opening to a particular cause of action will entitle the defendant to dismissal of the omitted cause of action.
But in Beshay v. Eberhart the Appellate Division clarifies that dismissal after the opening statement of plaintiff's counsel is limited to situations in which (1) the complaint fails to state a cause of action, (2) the opening statement admits as fact a defense which has been interposed, or (3) plaintiff's counsel makes an admission or statement which so completely compromises his or her case that the court is justified in awarding judgment as a matter of law to the defendant. The decision can be found here.
In Hanrahan v. Riverhead the Second Circuit addresses CPLR § 1003 which authorizes a New York trial court to dismiss a complaint for failure to join a necessary party. The court notes that § 1003 calls for dismissal without prejudice, which means it is not a dismissal on the merits.
After suffering a § 1003 dismissal, plaintiff Hanrahan brought suit in federal court instead of refiling in state court. Because the § 1003 dismissal was not on the merits, the Circuit Court concludes that the federal action is not barred by res judicata.
The Second Circuit does give a procedural warning: a dismissal by the New York courts on the grounds a suit is untimely is considered a dismissal on the merits by the New York Court of Appeals. A suit dismissed in the New York courts on statute of limitations grounds and later brought in federal court will, therefore, be dismissed in federal court on grounds of res judicata. The Second Circuit opinion can be found here.