Release can operate as an affirmative defense, but sometimes the invocation of mootness can even be more effective to quickly terminate a pending case or appeal.
WHEN DOES THE MOOTNESS DOCTRINE KICK IN?
A case becomes moot when: (1) it appears that a party seeks to obtain a judgment upon some controversy, when in reality none exists; or (2) a party seeks a judgment upon some matter, which cannot have any practical legal effect upon a then existing controversy. Camarena v. Tex. Employment Comm'n, 754 S.W.2d 149, 151 (Tex. 1988); Robinson v. Alief Indep. Sch. Dist., 298 S.W.3d 321, 324 (Tex. App.-Houston [14th Dist.] 2009, pet. denied).
EFFECT OF UNCONDITIONAL RELEASE OF JUDGMENT
"An unconditional release of judgment operates as a total relinquishment of all rights of the judgment creditor in the judgment. It is a complete discharge of the debt created by the judgment and a complete surrender of the judgment creditor's rights in the judgment." Rapp v. Mandell & Wright, P.C., 123 S.W.3d 431, 435 (Tex. App.-Houston [14th Dist.] 2003, pet. denied).
SOURCE: HOUSTON COURT OF APPEALS - 14-13-00467-CV - 1/9/2014
NATURE OF MOOTNESS DOCTRINE AND EFFECT ON PENDING APPEAL
The mootness doctrine limits courts to deciding cases in which an actual controversy exists. Ex parte Flores, 130 S.W.3d 100, 104-05 (Tex. App.-El Paso 2003, pet. ref'd). When there has ceased to be a controversy between the litigating parties, which is due to events occurring after judgment has been rendered by the trial court, the decision of an appellate court would be a mere academic exercise and the court may not decide the appeal. Id. A case that is moot is normally not justiciable. Pharris v. State, 165 S.W.3d 681, 687-88 (Tex. Crim. App. 2005).
One of the exceptions to the general rule is when a claim is "capable of repetition, yet evading review." The United States Supreme Court has said that "the `capable of repetition but evading review' doctrine [is] limited to the situation where two elements combine: (1) the challenged action was in its duration too short to be fully litigated prior to its cessation or expiration, and (2) there was a reasonable expectation that the same complaining party would be subjected to the same action again." Weinstein v. Bradford, 423 U.S. 147, 149 (1975). The Texas Court of Criminal Appeals has adopted and applied this doctrine. See Pharris, 165 S.W.3d at 688.
SOURCE: HOUSTON COURT OF APPEALS FOR THE FOURTEENTH DISTRICT - 14-13-00647-CR - 2/6/2014 EX PARTE BRADSHAW, Tex: Court of Appeals, 14th Dist. 2014 (criminal case context)