Under Article III of the U.S. Constitution, the jurisdiction of federal courts is limited to actual, ongoing cases and controversies. From this constitutional requirement comes several "justiciability" doctrines that may be invoked in federal court actions that could prevent plaintiffs from maintaining a legal claim against defendants. The four justiciability doctrines are standing, ripeness, political question, and mootness. These doctrines will render a controversy "nonjusticiable" if a court decides that any one of them applies. Standing addresses whether the plaintiff is the proper party to assert a claim in federal court. Ripeness considers whether a party has brought an action too early for adjudication. The political question doctrine makes nonjusticiable controversies that involve an issue constitutionally committed to the political branches of government. There are two types of mootness: Article III mootness and prudential mootness. As the name implies, the former is derived from the constitutional requirement that judicial power be exercised only in "cases" or "controversies." The latter concerns a federal court's discretion to withhold use of judicial power in suits that--while not actually moot--should be treated as moot for "prudential" reasons. Usually, a case or controversy must exist throughout all stages of federal judicial proceedings, and not just when the lawsuit is filed or when review is granted by an appellate court. The dispute must concern "live" issues, and generally, the plaintiffs must have a personal interest in the outcome of the case. The Supreme Court has described mootness as follows: The "personal stake" aspect of mootness doctrine ... serves primarily the purpose of assuring that federal courts are presented with disputes they are capable of resolving. One commentator has defined mootness as "the doctrine of standing set in a time frame: The requisite personal interest that must exist at the commencement of the litigation (standing) must continue throughout its existence (mootness)." When a legal claim becomes moot while awaiting appellate review, the established practice is for the federal appeals court to reverse or vacate the judgment below and to remand the case to the district court with an instruction to dismiss the action. That consequence is because a moot case does not qualify as a "case or controversy" under Article III; due to the lack of jurisdiction, federal courts have no power to consider the merits of a constitutionally moot case. Cases may be rendered moot because of a change in the status of the parties or in the law, or because of an act of one of the parties that dissolves the controversy. The following paragraphs provide examples of these scenarios. When a white law school applicant challenged the constitutionality of a public law school's affirmative action admissions policy, he was admitted to the school pursuant to a trial court ruling that found in his favor. During his second year of law school, the state's supreme court reversed the lower court's decision. By the time the Supreme Court granted certiorari to hear the case, the student was in his final school term. The Court dismissed the case as moot because "the petitioner will complete his law school studies at the end of the term for which he has now registered regardless of any decision this Court might reach on the merits of this litigation...." A lawsuit was filed claiming that the suspension and termination of disability benefit payments under the Social Security Act violated the procedural due process rights of the recipients. Before oral argument before the Supreme Court, the Secretary of Health, Education, and Welfare adopted new regulations governing the procedures to be followed by the Social Security Administration in determining whether to suspend or terminate disability benefits. In light of this development, the Court held "that the appropriate course is to withhold judicial action pending reprocessing, under the new regulations, of the determinations here in dispute. If that process results in a determination of entitlement to disability benefits, there will be no need to consider the constitutional claim that claimants are entitled to an opportunity to make an oral presentation." A prison inmate was transferred by corrections authorities, without notice or an opportunity for a hearing, from a medium security prison to a maximum security prison. The inmate filed a lawsuit alleging a violation of his due process rights under the Fourteenth Amendment of the U.S. Constitution; however, while his appeal was pending, he was transferred twice, first back to the medium security facility and thereafter to a minimum security institution. The Supreme Court held that the suit no longer presented a case or controversy, and thus dismissed the case as moot. Equitable, or prudential mootness, has been referred to as the "cousin of the mootness doctrine" and described as relating to the court's discretion in matters of remedy and judicial administration. Unlike Article III mootness, [it] address[es] not the power to grant relief but the court's discretion in the exercise of that power. In some circumstances, a controversy, not actually moot, is so attenuated that considerations of prudence and comity for coordinate branches of government counsel the court to stay its hand, and to withhold relief it has the power to grant. Thus, while a case may not be moot for failure to meet Article III's requirements, a court may nevertheless "treat [the case] as moot for prudential reasons" and decline to exercise judicial power in the case. The doctrine of prudential mootness is often applied in cases where the federal court declines to grant the plaintiff's request for declaratory judgment or injunctive relief because the defendant "has already changed or is in the process of changing its policies or where it appears that any repeat of the actions in question is otherwise highly unlikely." The Supreme Court has explained that the burden on the party asking the court to dismiss a case on prudential mootness grounds is a "heavy one," as the movant (usually the defendant) must "demonstrate that there is no reasonable expectation that the wrong will be repeated." The Supreme Court has recognized several exceptions to the mootness doctrine that, if found to apply to a case, would permit federal court adjudication of the dispute. In Sibron v. New York , an individual convicted of unlawful possession of heroin had completed service of his prison sentence prior to Supreme Court review of the case. The Court explained that the case was not moot: Although the term has been served, the results of the conviction may persist. Subsequent convictions may carry heavier penalties, civil rights may be affected. As the power to remedy an invalid sentence exists, we think, respondent is entitled to an opportunity to attempt to show that this conviction was invalid. This exception to the mootness doctrine thus applies in the criminal context, when there is a "possibility that any collateral legal consequences will be imposed on the basis of the challenged conviction." Even a "remote" possibility of such consequences is enough to save a criminal case from becoming moot. Some disputes or injuries may arise in the short-term and have the potential for recurrence, but always fail to last long enough to permit federal judicial review. In such a situation, federal courts have justified an exception to the mootness doctrine. A classic example is the landmark abortion case, Roe v. Wade. The Supreme Court explained why the exception should be invoked in this instance: [W]hen, as here, pregnancy is a significant fact in the litigation, the normal 266-day human gestation period is so short that the pregnancy will come to term before the usual appellate process is complete. If that termination makes a case moot, pregnancy litigation seldom will survive much beyond the trial stage, and appellate review will be effectively denied. Our law should not be that rigid. Pregnancy often comes more than once to the same woman, and in the general population, if man is to survive, it will always be with us. However, the Court has held that this exception applies only in "exceptional situations," where the plaintiff "can make a reasonable showing that he will again be subjected to the alleged illegality." If a defendant voluntarily terminates the allegedly unlawful conduct after the lawsuit has been filed but retains the power to resume the practice at any time, a federal court may deem the case nonmoot. The "heavy burden" of persuading the court that a case has been mooted by the defendant's voluntary actions lies with the party asserting mootness, and the standard for such a determination is a "stringent" one: "if subsequent events ma[ke] it absolutely clear that the allegedly wrongful behavior [can] not reasonably be expected to recur." This exception is supported by the Supreme Court because, in addition to ensuring that the defendant is not "free to return to his old ways," there is "a public interest in having the legality of the practices settled." For example, an environmental group had filed a citizen suit under the Clean Water Act against Laidlaw, a company that operated a wastewater treatment plant, alleging that the plant had discharged far more toxic pollutants into a river than it was allowed under terms of a government-issued permit. However, after the lawsuit began, Laidlaw began to comply with the discharge limit. The Supreme Court held that this case was not moot because it was a "disputed factual matter" whether the company's substantial compliance with its permit requirements, or its closure of the facility in question (which had occurred after the court of appeals had issued its decision), would make "it absolutely clear that Laidlaw's permit violations could not reasonably be expected to recur." When the claim of the named plaintiff in a certified class action becomes moot, the class action will not be dismissed so long as a member of the class continues to have a sufficiently adversarial relationship to constitute a live controversy. For example, a plaintiff brought a class action to challenge a one-year residency requirement in a state divorce statute, on the ground that it violated the U.S. Constitution. By the time her case reached the Supreme Court, she had long since satisfied the state's durational residency requirement, a development that, had she filed the suit only on her own behalf, would have made the case moot because she no longer retained a personal stake in the outcome. However, the Court noted the significant fact that she had brought the lawsuit as a class action in a representative capacity, which affected the mootness determination: "When the District Court certified the propriety of the class action, the class of unnamed persons described in the certification acquired a legal status separate from the interest asserted by [the named representative]," and therefore the Article III "cases or controversies" requirement was satisfied.

Summary:
A case pending before a federal court may at some point in the litigation process lose an element of justiciability and become "moot." Mootness may occur when a controversy initially existing at the time the lawsuit was filed is no longer "live" due to a change in the law or in the status of the parties involved, or due to an act of one of the parties that dissolves the dispute. When a federal court deems a case to be moot, the court no longer has the power to entertain the legal claims and must dismiss the complaint. However, the U.S. Supreme Court over time has developed several exceptions to the mootness doctrine. This report provides a general overview of the doctrine of "mootness," as the principle is understood and used by federal courts to decide whether to dismiss certain actions for lack of jurisdiction.