Although a Motion for Nonsuit or a Notice of Nonsuit is effective immediately upon filing, there must still be an order formally dismissing the case. Texas Rule of Civil Procedure 162 reads as follows:
At any time before the plaintiff has introduced all of his evidence other than rebuttal evidence, the plaintiff may dismiss a case, or take a non-suit, which shall be entered in the minutes. Notice of the dismissal or non-suit shall be served in accordance with Rule 21 a on any party who has answered or has been served with process without necessity of court order. Any dismissal pursuant to this rule shall not prejudice the right of an adverse party to be heard on a pending claim for affirmative relief or excuse the payment of all costs taxed by the clerk. A dismissal under this rule shall have no effect on any motion for sanctions, attorney’s fees or other costs, pending at the time of dismissal, as determined by the court. Any dismissal pursuant to this rule which terminates the case shall authorize the clerk to tax court costs against dismissing party unless otherwise ordered by the court.
The phrase “without necessity of court order” does not mean that an order formally dismissing the case is not necessary. The Supreme Court of Texas sets forth a particularly good reason why an order is necessary:
The nonsuit extinguishes a case or controversy from the moment the motion is filed or an oral motion is made in open court; the only requirement is the mere filing of the motion with the clerk of the court.
However, the signing of an order dismissing a case, not the filing of a notice of nonsuit, is the starting point for determining when a trial court’s plenary power expires. Appellate timetables do not run from the date a nonsuit is filed, but rather from the date the trial court signs an order of dismissal.
An order is necessary in order to establish appellate deadlines. In addition, a deadline needs to be established for the court’s plenary powers in light of the balance of Rule 162, which specifically allows the trial court to assess sanctions, attorneys’ fees, and costs after the nonsuit is taken.
The necessity of an order is further reinforced when taking into consideration bogus counterclaims for declaratory relief. In some cases, a defendant may have good reason to dispute a nonsuit, especially if res judicata may prevent future lawsuits. In such instances, although a nonsuit has been filed, the trial court will need to determine whether a counterclaim exists that prevents the dismissal of the case as a whole.
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 Univ. of Tex. Med. Branch at Galveston v. Estate of Blackmon, 195 S.W.3d 98, 100 (Tex. 2006).
 In re Bennett, 960 S.W.2d 35, 38 (Tex. 1997).
 See BHP Petroleum Co. v. Millard, 800 S.W.2d 838 (Tex. 1990).