What authority does a plaintiff have to voluntarily dismiss an action with or without prejudice?

"Code of Civil Procedure section 581, subdivision (b), provides that an action may be dismissed '(1) With or without prejudice, upon written request of the plaintiff to the clerk, filed with papers in the case, or by oral or written request to the court at any time before the actual commencement of trial, upon payment of the costs, if any. . . .' Similar authority is found in subdivision (c) of that same section: 'A plaintiff may dismiss his or her complaint, or any cause of action asserted in it, in its entirety, or as to any defendant or defendants, with or without prejudice prior to the actual commencement of trial.' [] The right of a plaintiff to voluntarily dismiss an action before commencement of trial is not absolute. Code of Civil Procedure section 581 recognizes exceptions to the right; other limitations have evolved through the courts' construction of the term 'commencement of trial.' These exceptions generally arise where the action has proceeded to a determinative adjudication, or to a decision that is tantamount to an adjudication." (Harris v. Billings (1993) 16 Cal.App.4th 1396, 1401-1402.)

In Harris v. Billings, supra, 16 Cal.App.4th 1396, we held that a trial court erred in changing a voluntary dismissal from one without prejudice to a dismissal with prejudice. Once a voluntary dismissal has been properly entered under Code of Civil Procedure section 581, "'the trial court is without jurisdiction to act further in the action [citations] except for the limited purpose of awarding costs and statutory attorney's fees. [Citations.]'" (Harris v. Billings, supra, 16 Cal.App.4th at p. 1405.)