Are dismissals with prejudice unless otherwise stated?

Or does this vary from state to state?

Just the contrary. If a case is dismissed, the suit (action, petition, etc.) can be reinstituted unless the dismissal was on the merits of the case or for some other reason precluding a new filing, such as Statute of limitations, Statute of Frauds, etc. Such a dismissal should state “with prejudice.”

That’s not the case in Illinois, or in the Federal system. Dismissals are presumed to be with prejudice (or on the merits), unless the reason for the dismissal falls into a limited number of categories (dismissal for want of jurisdiction, for example) or unless the dismissal is expressly stated to be without prejudice. See FRCP 43(b)

New York Civil Practice Law & Rules 3217© provides:

There is no “FRCP 43(b)” – I think that you mean Rule 41(b):

But as the rule’s title suggests, it refers only to an involuntary dismissal. A voluntary dismissal in the federal system, with or without an order of the court, usually is without prejudice:

(Emphasis added.)

You are correct, I was referring to Rule 41(b). (43 was a typo.)

I also agree that 41(b) applies to involuntary dismissals only, which is what I assumed (perhaps too quickly) that Liberal was asking about.

Illinois law has the same distinction between voluntary and involuntary dismissals.