with whom Justice O’Connor joins, dissenting.
Without expressing any views on the merits of this case, I respectfully dissent because in my opinion we have no authority to decide it. I think the controversy is moot.
I
The Court correctly acknowledges that we have no power under Art. Ill of the Constitution to adjudicate a case that no *333longer presents an actual, ongoing dispute between the named parties. Ante, at 317, citing Nebraska Press Assn. v. Stuart, 427 U. S. 539, 546 (1976); Preiser v. Newkirk, 422 U. S. 395, 401 (1975). Here, there is obviously no present controversy between the parties, since both respondents are no longer in school and therefore no longer subject to a unilateral “change in placement.” The Court concedes mootness with respect to respondent John Doe, who is now too old to receive the benefits of the Education of the Handicapped Act (EHA). Ante, at 318. It concludes, however, that the case is not moot as to respondent Jack Smith, who has two more years of eligibility but is no longer in the public schools, because the controversy is “capable of repetition, yet evading review.” Ante, at 318-323.
Jurisdiction on the basis that a dispute is “capable of repetition, yet evading review” is limited to the “exceptional situation],” Los Angeles v. Lyons, 461 U. S. 95, 109 (1983), where the following two circumstances simultaneously occur: “ ‘(1) the challenged action [is] in its duration too short to be fully litigated prior to its cessation or expiration, and (2) there [is] a reasonable expectation that the same complaining party would be subjected to the same action again.’” Murphy v. Hunt, 455 U. S. 478, 482 (1982) (per curiam), quoting Weinstein v. Bradford, 423 U. S. 147, 149 (1975) (per curiam). The second of these requirements is not met in this case.
For there to be a “reasonable expectation” that Smith will be subjected to the same action again, that event must be a “demonstrated probability.” Murphy v. Hunt, supra, at 482, 483; Weinstein v. Bradford, supra, at 149. I am surprised by the Court’s contention, fraught with potential for future mischief, that “reasonable expectation” is satisfied by something less than “demonstrated probability.” Ante, at 318-319, n. 6. No one expects that to happen which he does not think probable; and his expectation cannot be shown to be reasonable unless the probability is demonstrated. Thus, as the Court notes, our cases recite the two descriptions side by *334side (“a ‘reasonable expectation’ or a ‘demonstrated probability,’” Hunt, supra, at 482). The Court asserts, however, that these standards are “described ... in the disjunctive,” ante, at 318-319, n. 6 — evidently believing that the conjunction “or” has no accepted usage except a disjunctive one, i. e., “expressing an alternative, contrast, or opposition,” Webster’s Third New International Dictionary 651 (1981). In fact, however, the conjunction is often used “to indicate ... (3) the synonymous, equivalent, or substitutive character of two words or phrases (fell over a precipice [or] cliff) (the off [or] far side) (lessen [or] abate); (4) correction or greater exactness of phrasing or meaning (these essays, [or] rather rough sketches) (the present king had no children— [or] no legitimate children . . .).” Id., at 1585. It is obvious that in saying “a reasonable expectation or a demonstrated probability” we have used the conjunction in one of the latter, or nondisjunctive, senses. Otherwise (and according to the Court’s exegesis), we would have been saying that a controversy is sufficiently likely to recur if either a certain degree of probability exists or a higher degree of probability exists. That is rather like a statute giving the vote to persons who are “18 or 21.” A bare six years ago, the author of today’s opinion and one other Member of the majority plainly understood “reasonable expectation” and “demonstrated probability” to be synonymous. Cf. Edgar v. MITE Corp., 457 U. S. 624, 662, and n. 11 (1982) (Marshall, J., dissenting, joined by Brennan, J.) (using the two terms here at issue interchangeably, and concluding that the case is moot because “there is no demonstrated probability that the State will have occasion to prevent MITE from making a takeover offer for some other corporation”) (emphasis added).
The prior holdings cited by the Court in a footnote, see ante, at 319, n. 6, offer no support for the novel proposition that less than a probability of recurrence is sufficient to avoid mootness. In Burlington Northern R. Co. v. Maintenance of Way Employes, 481 U. S. 429, 436, n. 4 (1987), we found *335that the same railroad and union were “reasonably likely” to find themselves in a recurring dispute over the same issue. Similarly, in California Coastal Comm’n v. Granite Rock Co., 480 U. S. 572, 578 (1987), we found it “likely” that the plaintiff mining company would submit new plans which the State would seek to subject to its coastal permit requirements. See Webster’s Third New International Dictionary 1310 (1981) (defining “likely” as “of such a nature or so circumstanced as to make something probable[;]. . . seeming to justify belief or expectation^]... in all probability”). In the cases involving exclusion orders issued to prevent the press from attending criminal trials, we found that “[i]t can reasonably be assumed” that a news organization covering the area in which the defendant court sat will again be subjected to that court’s closure rules. Press-Enterprise Co. v. Superior Court of Cal., Riverside County, 478 U. S. 1, 6 (1986); Globe Newspaper Co. v. Superior Court of Norfolk County, 457 U. S. 596, 603 (1982). In these and other cases, one may quarrel, perhaps, with the accuracy of the Court’s probability assessment; but there is no doubt that assessment was regarded as necessary to establish jurisdiction.
In Roe v. Wade, 410 U. S. 113, 125 (1973), we found that the “human gestation period is so short that the pregnancy will come to term before the usual appellate process is complete,” so that “pregnancy litigation seldom will survive much beyond the trial stage, and appellate review will be effectively denied.” Roe, at least one other abortion case, see Doe v. Bolton, 410 U. S. 179, 187 (1973), and some of our election law decisions, see Rosario v. Rockefeller, 410 U. S. 752, 756, n. 5 (1973); Dunn v. Blumstein, 405 U. S. 330, 333, n. 2 (1972), differ from the body of our mootness jurisprudence not in accepting less than a probability that the issue will recur, in a manner evading review, between the same parties; but in dispensing with the same-party requirement entirely, focusing instead upon the great likelihood that the issue will recur between the defendant and the other members *336of the public at large without ever reaching us. Arguably those cases have been limited to their facts, or to the narrow areas of abortion and election rights, by our more recent insistence that, at least in the absence of a class action, the “capable of repetition” doctrine applies only where “there [is] a ‘reasonable expectation’” that the “same complaining party” would be subjected to the same action again. Hunt, 455 U. S., at 482 (emphasis added), quoting Weinstein, 423 U. S., at 149; see Burlington Northern R. Co., supra, at 436, n. 4; Illinois Elections Bd. v. Socialist Workers Party, 440 U. S. 173, 187 (1979). If those earlier cases have not been so limited, however, the conditions for their application do not in any event exist here. There is no extraordinary improbability of the present issue’s reaching us as a traditionally live controversy. It would have done so in this very case if Smith had not chosen to leave public school. In sum, on any analysis, the proposition the Court asserts in the present case — that probability need not be shown in order to establish the “same-party-recurrence” exception to mootness —is a significant departure from settled law.
II
If our established mode of analysis were followed, the conclusion that a live controversy exists in the present case would require a demonstrated probability that all of the following events will occur: (1) Smith will return to public school; (2) he will be placed in an educational setting that is unable to tolerate his dangerous behavior; (3) he will again engage in dangerous behavior; and (4) local school officials will again attempt unilaterally to change his placement and the state defendants will fail to prevent such action. The Court spends considerable time establishing that the last two of these events are likely to recur, but relegates to a footnote its discussion of the first event, upon which all others depend, and only briefly alludes to the second. Neither the facts in *337the record, nor even the extrarecord assurances of counsel, establish a demonstrated probability of either of them.
With respect to whether Smith will return to school, at oral argument Smith’s counsel forthrightly conceded that she “cannot represent whether in fact either of these students will ask for further education from the Petitioners.” Tr. of Oral Arg. 23. Rather, she observed, respondents would “look to [our decision in this case] to find out what will happen after that.” Id., at 23-24. When pressed, the most counsel would say was that, in her view, the 20-year-old Smith could seek to return to public school because he has not graduated, he is handicapped, and he has a right to an education. Id., at 27. I do not perceive the principle that would enable us to leap from the proposition that Smith could reenter public school to the conclusion that it is a demonstrated probability he will do so.
The Court nevertheless concludes that “there is at the very least a reasonable expectation” that Smith will return to school. Ante, at 319, n. 6. I cannot possibly dispute that on the basis of the Court’s terminology. Once it is accepted that a “reasonable expectation” can exist without a demonstrable probability that the event in question will occur, the phrase has been deprived of all meaning, and the Court can give it whatever application it wishes without fear of effective contradiction. It is worth pointing out, however, how slim are the reeds upon which this conclusion of “reasonable expectation” (whatever that means) rests. The Court bases its determination on three observations from the record and oral argument. First, it notes that Smith has been pressing this lawsuit since 1980. It suffices to observe that the equivalent argument can be made in every case that remains active and pending; we have hitherto avoided equating the existence of a case or controversy with the existence of a lawsuit. Second, the Court observes that Smith has “as great a need of a high school education and diploma as any of his peers.” Ibid. While this is undoubtedly good advice, it hardly estab*338lishes that the 20-year-old Smith is likely to return to high school, much less to public high school. Finally, the Court notes that counsel “advises us that [Smith] is awaiting the outcome of this case to decide whether to pursue his degree.” Ibid. Not only do I not think this establishes a current case or controversy, I think it a most conclusive indication that no current case or controversy exists. We do not sit to broaden decisionmaking options, but to adjudicate the lawfulness of acts that have happened or, at most, are about to occur.
The conclusion that the case is moot is reinforced, moreover, when one considers that, even if Smith does return to public school, the controversy will still not recur unless he is again placed in an educational setting that is unable to tolerate his behavior. It seems to me not only not demonstrably probable, but indeed quite unlikely, given what is now known about Smith’s behavioral problems, that local school authorities would again place him in an educational setting that could not control his dangerous conduct, causing a suspension that would replicate the legal issues in this suit. The majority dismisses this further contingency by noting that the school authorities have an obligation under the EHA to provide an “appropriate” education in “the least restrictive environment.” Ante, at 321. This means, however, the least restrictive environment appropriate for the particular child. The Court observes that “the preparation of an [individualized educational placement]” is “an inexact science at best,” ibid., thereby implying that the school authorities are likely to get it wrong. Even accepting this assumption, which seems to me contrary to the premises of the Act, I see no reason further to assume that they will get it wrong by making the same mistake they did last time — assigning Smith to too ^restrictive an environment, from which he will thereafter be suspended — rather than by assigning him to too restrictive an environment. The latter, which seems to me more likely than the former (though both combined are much less likely than a correct placement), might produce a law*339suit, but not a lawsuit involving the issues that we have before us here.
Ill
The Chief Justice joins the majority opinion on the ground, not that this case is not moot, but that where the events giving rise to the mootness have occurred after we have granted certiorari we may disregard them, since mootness is only a prudential doctrine and not part of the “case or controversy” requirement of Art. III. I do not see how that can be. There is no more reason to intuit that mootness is merely a prudential doctrine than to intuit that initial standing is. Both doctrines have equivalently deep roots in the common-law understanding, and hence the constitutional understanding, of what makes a matter appropriate for judicial disposition. See Flast v. Cohen, 392 U. S. 83, 95 (1968) (describing mootness and standing as various illustrations of the requirement of “justiciability” in Art. III).
The Chief Justice relies upon the fact that an 1895 case discussing mootness, Mills v. Green, 159 U. S. 651, makes no mention of the Constitution. But there is little doubt that the Court believed the doctrine called into question the Court’s power and not merely its prudence, for (in an opinion by the same Justice who wrote Mills) it had said two years earlier:
“[T]he court is not empowered to decide moot questions or abstract propositions, or to declare . . . principles or rules of law which cannot affect the result as to the thing in issue in the case before it. No stipulation of parties or counsel. . . can enlarge the power, or affect the duty, of the court in this regard.” California v. San Pablo & Tulare R. Co., 149 U. S. 308, 314 (1893) (Gray, J.) (emphasis added).
If it seems peculiar to the modern lawyer that our 19th-century mootness cases make no explicit mention of Art. Ill, that is a peculiarity shared with our 19th-century, and even *340our early 20th-century, standing cases. As late as 1919, in dismissing a suit for lack of standing we said simply:
“Considerations of propriety, as well as long-established practice, demand that we refrain from passing upon the constitutionality of an act of Congress unless obliged to do so in the proper performance of our judicial function, when the question is raised by a party whose interests entitle him to raise it.” Blair v. United States, 250 U. S. 273, 279.
See also, e. g., Standard Stock Food Co. v. Wright, 225 U. S. 540, 550 (1912); Southern R. Co. v. King, 217 U. S. 524, 534 (1910); Turpin v. Lemon, 187 U. S. 51, 60-61 (1902); Tyler v. Judges of Court of Registration, 179 U. S. 405, 409 (1900). The same is also true of our early cases dismissing actions lacking truly adverse parties, that is, collusive actions. See, e. g., Cleveland v. Chamberlain, 1 Black 419, 425-426 (1862); Lord v. Veazie, 8 How. 251, 254-256 (1850). The explanation for this ellipsis is that the courts simply chose to refer directly to the traditional, fundamental limitations upon the powers of common-law courts, rather than referring to Art. Ill which in turn adopts those limitations through terms (“The judicial Power”; “Cases”; “Controversies”) that have virtually no meaning except by reference to that tradition. The ultimate circularity, coming back in the end to tradition, is evident in the statement by Justice Field:
“By cases and controversies are intended the claims of litigants brought before the courts for determination by such regular proceedings as are established by law or custom for the protection or enforcement of rights, or the prevention, redress, or punishment of wrongs. Whenever the claim of a party under the constitution, laws, or treaties of the United States takes such a form that the judicial power is capable of acting upon it, then it has become a case.” In re Pacific Railway Comm’n, 32 F. 241, 255 (CC ND Cal. 1887).
*341See also 2 M. Farrand, Records of the Federal Convention of 1787, p. 430 (rev. ed. 1966):
“Doer. Johnson moved to insert the words ‘this Constitution and the’ before the word ‘laws.’
“Mr. Madison doubted whether it was not going too far to extend the jurisdiction of the Court generally to cases arising Under the Constitution, & whether it ought not to be limited to cases of a Judiciary Nature. The right of expounding the Constitution in cases not of this nature ought not to be given to that Department.
“The motion of Doer. Johnson was agreed to nem: con: it being generally supposed that the jurisdiction given was constructively limited to cases of a Judiciary nature.”
In sum, I cannot believe that it is only our prudence, and nothing inherent in the understood nature of “The judicial Power,” U. S. Const., Art. Ill, §1, that restrains us from pronouncing judgment in a case that the parties have settled, or a case involving a nonsurviving claim where the plaintiff has died, or a case where the law has been changed so that the basis of the dispute no longer exists, or a case where conduct sought to be enjoined has ceased and will not recur. Where the conduct has ceased for the time being but there is a demonstrated probability that it will recur, a real-life controversy between parties with a personal stake in the outcome continues to exist, and Art. Ill is no more violated than it is violated by entertaining a declaratory judgment action. But that is the limit of our power. I agree with The Chief Justice to this extent: the “yet evading review” portion of our “capable of repetition, yet evading review” test is prudential; whether or not that criterion is met, a justiciable controversy exists. But the probability of recurrence between the same parties is essential to our jurisdiction as a court, and it is that deficiency which the case before us presents.
It is assuredly frustrating to find that a jurisdictional impediment prevents us from reaching the important merits *342issues that were the reason for our agreeing to hear this case. But we cannot ignore such impediments for purposes of our appellate review without simultaneously affecting the principles that govern district courts in their assertion or retention of original jurisdiction. We thus do substantial harm to a governmental structure designed to restrict the courts to matters that actually affect the litigants before them.