delivered the opinion of the Court. Smith and Eldridge, JJ., dissent. Smith, J., filed a dissenting opinion at page 330 infra, in which Eldridge, J., concurs.
Maryland Code (1978), § 5-201(c)(13) of the Education Article provides that the State shall pay for “the necessary costs of transporting students ... to public schools.” 1 The State reimburses the counties for their costs according to a formula. 2 Md. Register 1314, 1482-83.2 However, the counties may supplement the amount reimbursed. § 7-601 of *326the Education Article. The total amount of reimbursement is determined annually.
Some counties own and operate school buses while others contract for essentially all of the needed buses and operators. See § 7-602 of the Education Article. While the Board of Education of Anne Arundel County (Board) owns some buses, it contracts for the great majority of its needed school bus services. Many of the school bus contractors belong to the Anne Arundel County School Bus Contractors Association, Inc. (Association), a trade association.
In February, 1975, the Association’s request for a county rate supplement was stricken, for some unexplained reason, from the 1975-76 budget proposed by the Board. In September, 1975, the Association requested a $.06 per mile county rate supplement. Thereafter, the Association agreed to an audit which was completed in January, 1976. As a result of the audit, the Board included a $.06 per mile rate supplement in its proposed budget for the year 1976-77. Again, for some unexplained reason, this proposed county rate supplement was stricken. The Association learned of this deletion sometime before 30 March 1976.
At an Association meeting held on 30 March 1976, various members agreed that as of the close of school on 2 April 1976, they would stop driving if they did not obtain a rate supplement of $.06 per mile retroactive to 1 September 1975. On 31 March 1976, the Association’s president informed the Supervisor of Transportation of that decision. On 1 April 1976, there was a meeting between the Association and the Board at which the Board asked the Association to put its demands in writing, and the Association complied. A further meeting was scheduled for 7 April 1976.
On 2 April 1976, in the Circuit Court for Anne Arundel County, the Board obtained an ex parte injunction restraining the appellees, the Association and certain of its members (Association), from refusing to drive. On 9 April 1976, this injunction was extended for 10 days. On 12 April 1976, the trial court permitted the appellant, the Attorney General of the State of Maryland (Attorney General), to intervene. On 13 April 1976, he filed a bill of complaint seeking a declaration *327that the Association, by threatening to withhold services in order to obtain an agreed upon rate supplement, “engaged in an unlawful combination or conspiracy in unreasonable restraint of trade” in violation of the Maryland Antitrust Act, Md. Code (1975), § ll-204(a)(l) of the Commercial Law Article. In addition, the Attorney General sought an interlocutory injunction and a permanent injunction restraining the Association for a period of 10 years from further violations of the Antitrust Act, from itself withholding transportation services from the Board, and from inducing others to withhold such services. On 14 April 1976, the trial court, with the agreement and consent of the parties, issued an interlocutory injunction continuing the ex parte injunction of 2 April 1976 through 1 September 1976.
On 18 July 1977, the Attorney General filed a motion for summary judgment. On 8 September 1977, the Association filed a motion for summary judgment. On 12 December 1977, the trial court entered an order denying the Attorney General’s motion and granting the Association's motion. We issued a writ of certiorari to the Court of Special Appeals before consideration by that Court. After argument and reargument, we find the case to be moot. We shall dismiss the appeal.
Generally, appellate courts do not decide academic or moot questions, A question is moot if, at the time it is before the court, there is no longer an existing controversy between the parties, so that there is no longer any effective remedy which the court can provide. State v. Ficker, 266 Md. 500, 506-07, 295 A.2d 231, 234-35 (1972); Lloyd v. Board of Supervisors of Elections, 206 Md. 86, 39, 111 A.2d 379, 380 (1954); State v. Haas, 188 Md. 63, 66, 51 A.2d 647, 648 (1947). See Bishop v. Governor of Md., 281 Md. 521, 524-26, 380 A.2d 220, 222-23 (1977). Accordingly, an injunction should not issue if the acts sought to be enjoined have been discontinued or abandoned. State v. Ficker, 266 Md. at 507, 295 A.2d at 235; United Bhd. of Carpenters v. United State Tile & Composition Roofers, 181 Md. 280, 282, 29 A.2d 839, 840 (1943).
Here the record shows that on 31 March 1976, the Association threatened to withhold transportation services. *328That threat was never carried out. On 2 April 1976, an injunction was issued which, with the agreement and consent of the Association, was extended to 1 September 1976. During the effective period of the injunction, the Association neither threatened to stop services nor did it in fact stop services. Moreover, the record shows that the Association ultimately-received and accepted a $.02 per mile supplement for the 1977-78 school year, thus terminating the controversy. There is no evidence to show that since the expiration of the injunction or the termination of the controversy, the Association either threatened to stop services or did in fact stop them. Thus, the record establishes that the activities which the Attorney General seeks to have enjoined have been discontinued. There is no existing controversy between the parties and no effective remedy the court can provide. Accordingly, the case is moot.
Of course, a court may decide a moot question where there is an imperative and manifest urgency to establish a rule of future conduct in matters of important public concern, which may frequently recur, and which, because of inherent time constraints, may not be able to be afforded complete appellate review. State v. Ficker, 266 Md. at 507, 295 A.2d at 235; Lloyd v. Board of Supervisors of Elections, 206 Md. at 43, 111 A.2d at 381. See Bishop v. Governor of Md., 281 Md. at 525, 380 A.2d at 223. Periods of two and three months have been held insufficient to afford complete appellate review, Sheehy v. Thomas, 155 Md. 688, 693, 142 A. 506, 507 (1928) (3 months); Close v. Southern Md. Agr. Ass’n, 134 Md. 629, 632, 108 A. 209, 210-11 (1919) (2 months), whereas periods of five and 12 months have been deemed sufficient for this purpose, Maryland Tobacco Growers’ Ass'n v. Maryland Tobacco Authority, 267 Md. 20, 25-26, 296 A.2d 578, 580-81 (1972) (12 months); Lloyd v. Board of Supervisors of Elections, 206 Md. at 44, 111 A.2d at 382 (5 months).
While we recognize that this case involves a matter of important public concern, we are persuaded that there is no imperative or manifest urgency to establish a rule of future conduct. In the absence of any evidence to show that in the four years since the expiration of the injunction, the *329Association has threatened to withhold services, or has in fact withheld them in order to obtain an agreed upon rate supplement, we can only conclude that similar activities and controversies between these parties are unlikely to recur.
In addition, there are no inherent time constraints which would necessarily prevent appellate review. There were five months between the Association’s decision to withhold services on 30 March 1976 and the expiration of the interlocutory injunction on 1 September 1976. Thus, even should a controversy with the same chronology as the present one occur in the future, there would be sufficient time for appellate review. Maryland Tobacco Growers’ Ass’n v. Maryland Tobacco Authority, 267 Md. at 25-26, 296 A.2d at 580-81; Lloyd v. Board of Supervisors of Elections, 206 Md. at 44, 111 A.2d at 382. Moreover, because the rate of reimbursement for providing transportation services is established annually, and is effective for one year, it is possible that, under different circumstances, similar activities and controversies would arise even earlier.
In this case, a peculiar combination of circumstances prevented the completion of appellate review. For two successive years, rate supplements which had been included in the Board’s budget were, for unexplained reasons, deleted as late as E'ebruary. It was not until sometime in March, 1976 that the Association learned that it was not to receive its anticipated rate supplement. Moreover, approximately 20 months elapsed from the time the Attorney General filed his complaint on 13 April 1976 until the trial court ruled on the cross motions for summary judgment on 12 December 1977. The Attorney General on 13 and 14 April 1976 did in fact request that the time for filing an answer and for notice of an oral deposition, respectively, be shortened. Yet, although the Attorney General knew on 14 April 1976 that the interlocutory injunction to which he had agreed and consented would expire on 1 September 1976, he made no other attempt throughout this 20 month period to expedite this case; neither did he attempt to expedite the proceedings in this Court. It is unlikely that a set of circumstances similar to those which prevented completion of appellate review in this case would *330in the future coalesce to prevent completion of appellate review of other similar activities and controversies should they recur.
None of the considerations which justify this Court in deciding a moot case is present. Under the circumstances here, we decline to decide this moot case. Md. Rule 835(a)(6).
Judgment of the Circuit Court for Anne Arundel County vacated and case remanded to that court with instructions to dismiss as moot. Costs to be paid by appellant.
. At the time of the events pertinent to this case, the provisions concerning school bus operations were codified in Md. Code (1957, 1969 Repl. Vol.), Art. 77. By the Acts of 1978, ch. 22, these provisions were placed in Md. Code (1978), titles 2, 5, and 7 of the Education Article.
. The State Board of Education’s bylaws, rules, and regulations have the force and effect of law. § 2-205 (c) (2) of the Education Article.