Partial dismissals in federal court present plaintiffs with a difficult choice, to seek an immediate appeal or continue litigating their lives claims. They cannot do both, though they are often motivated to do so, and defendants should be prepared to hold plaintiffs to that choice—as the Ninth Circuit indicated it was willing to do in comments during a recent oral argument.
Briefly stated, a plaintiff facing partial dismissal must meaningfully relinquish their live claims in order to appeal their dismissed claims. For example, if the district court dismisses an entire complaint, but grants leave to amend some claims, the plaintiff must decline to amend, passively in some Circuits or with affirmative notice in others. See WMX Technologies, Inc. v. Miller, 104 F.3d 1133, 1136 (9th Cir. 1997); Otis v. City of Chicago, 29 F.3d 1159, 1166–68 (7th Cir.1994). If the district court dismisses some claims, but allows others to proceed, the plaintiff must file a motion for voluntary dismissal under Rule 41(a)(2) or, a Rule 54(b) order in cases of partial summary judgment. See James v. Price Stern Sloan, Inc., 283 F.3d 1064 (9th Cir. 2002); Hicks v. NLO, Inc., 825 F.2d 118 (6th Cir.1987).
What the plaintiff cannot do, and here's the trap, is dismiss their live claims without prejudice in order to litigate those claims immediately in a separate action. See Dannenberg v. Software Toolworks, Inc., 16 F.3d 1073, 1076-77 (9th Cir. 1994). That kind of jurisdictional manipulation is strictly prohibited. And, reaching back to that recent, Ninth Circuit argument, it creates a risk that the plaintiff will be whipsawed between an order that dismisses the appeal for lack of jurisdiction and an opinion that finds jurisdiction, but rules that the underlying dismissal is res judicata to the separate action. It hardly bears pointing out, that's a great result for defense counsel on appeal.