This suit was filed by a group of Iranian students seeking a mandatory injunction to require the City of San Antonio to issue parade permits allowing them to demonstrate against the presence of the former Shah of Iran at Lackland Air Force Base in San Antonio. The trial court denied a temporary mandatory injunction and the court of civil appeals affirmed. 604 S.W.2d 379. We reverse the judgments below.
On December 3, 1979, about a month after the American hostages were seized in Iran, Ali Seyed Fanai Khayat and other members of the Iranian Muslim Organization (hereinafter referred to as the “Iranians”) applied to the City of San Antonio (hereafter “City”) for parade permits for two demonstrations. It is undisputed that the demonstrations, to protest against the former Shah of Iran, Rezi Pahlavi, were to be peaceful, as a prior demonstration by the Iranians had been. These applications evoked another application from the Ku Klux Klan to demonstrate at the same time and place as the Iranians. On December 4, the city manager denied these applications and announced that no permits would be issued any persons or groups on the Iranian issue. The Iranians then immediately filed this suit to permanently enjoin the City from interfering with their right of free speech and assembly and to temporarily enjoin the City to grant their parade permit. On December 6, a hearing was held by the district court on a temporary restraining order which was denied.
*205On December 10, five of the Iranians staged a hunger strike on the steps of City Hall. That demonstration ended two days later when the five Iranians were taken into protective custody by the police after an angry crowd stirred up by two disc jockeys gathered to taunt and threaten the demonstrators.
On December 11, the city council heard the Iranians’ appeal from the city manager’s decision. The council upheld the manager’s action at the conclusion of a public hearing and further banned other demonstrations by passing unanimously the following motion:
... I move the Council uphold the Manager’s decision and that permits be denied for public parades and/or demonstrations to the Iranian Muslim Student Association (sic) and others who encompass the cause either pro or con in the Iranian question.1
Then on December 17, following another hearing, the trial court denied a temporary injunction. The Iranians then appealed to the court of civil appeals which affirmed the trial court.
The court of civil appeals held that the denial of injunctive relief was justified. The court reasoned that because the Shah had already left the United States for Panama, no irreparable injury would occur to the Iranians arising out of their desire to be allowed to demonstrate while the Shah was still in San Antonio. The court concluded that there was “some basis upon which the trial court could have properly held that a mandatory order was not necessary to prevent irreparable injury” and that “the trial court did not abuse its discretion” in denying the temporary injunction.
The freedoms of speech, peaceable assembly and the right of petition, guaranteed by the first amendment to the Constitution of the United States, are basic to the fabric of our liberty.2 The rights to picket and demonstrate in public places, particularly streets, sidewalks, and parks, are extended first amendment protection. Lehman v. City of Shaker Heights, 418 U.S. 298, 303, 94 S.Ct. 2714, 2717, 41 L.Ed.2d 770 (1974); Shuttlesworth v. City of Birmingham, 394 U.S. 147, 89 S.Ct. 935, 22 L.Ed.2d 162 (1969); Cox v. Louisiana, 379 U.S. 536, 85 S.Ct. 453, 13 L.Ed.2d 471 (1965); Hague v. C.I.O., 307 U.S. 496, 515, 59 S.Ct. 954, 964, 83 L.Ed 1423 (1939). The Iranians’ march, if peaceful and orderly, falls well within the sphere of conduct protected by the first amendment. Gregory v. City of Chicago, 394 U.S. Ill, 89 S.Ct. 946, 22 L.Ed.2d 134 (1969). The state may reasonably regulate the time, place and manner of the exercise of first amendment rights as necessary to the protection of other compelling public interests, Grayned v. City of Rockford, 408 U.S. 104, 115-16, 92 S.Ct. 2294, 2302-3, 33 L.Ed.2d 222 (1972); Concerned Jewish Youth v. McGuire, 621 F.2d 471 (2nd Cir. 1980); however, limitations on the right to regulate the exercise of first amendment rights are essential, so that when discretion is vested in administrative officials, it must be “appropriate, limited discretion under properly drawn statutes or ordinances.” Cox v. Louisiana, supra, 379 U.S. 536, at 558, 85 S.Ct., at 466. Regulations which take the form of prior restraints are subject to particularly exacting judicial scrutiny with a heavy presumption against their constitutional validity. Nebraska Press Ass’n v. Stuart, 427 U.S. 539, 558, 96 S.Ct. 2791, 49 L.Ed.2d 688 (1976); Organization For a Better Austin v. Keefe, 402 U.S. 415, 91 S.Ct. 1575, 29 L.Ed.2d 1 (1971); Carroll v. President and Commr’s of Princess Anne, 393 U.S. 175, 181, 89 S.Ct. 347, 21 L.Ed.2d 325, 331 (1968); Near v. Minnesota, 283 U.S. 697, 51 S.Ct. 625, 75 L.Ed. 1357 (1931). As the U.S. Supreme Court said in Virginia *206Pharmacy Board v. Virginia Consumer Council, 425 U.S. 748, 771, 96 S.Ct. 1817, 48 L.Ed.2d 346 (1976):
We have often approved restriction [on time, place, and manner] provided that they are justified without reference to the content of the regulated speech, that they serve a significant governmental interest, and that in so doing they leave open ample alternative channels for communication of the information.
The one form of regulation which has never been approved by the supreme court is to restrict expression on the basis of the content or subject matter of that expression. Hudgens v. NLRB, 424 U.S. 507, 521, 96 S.Ct. 1029, 1039, 47 L.Ed.2d 196 (1976); Police Dept. of Chicago v. Mosley, 408 U.S. 92, 95, 92 S.Ct. 2286, 33 L.Ed.2d 212 (1972); Cox v. Louisiana, supra, 379 U.S. 536 at 557, 85 S.Ct. at 465. The court in Mosley, 408 U.S. at 95, 92 S.Ct. at 2290, announced that government not only is forbidden from discriminating between views it finds acceptable and those it finds unacceptable, but “it may not select which issues are worth discussing or debating in public facilities.” The court further admonishes that “this court has condemned licensing schemes that lodge broad discretion in a public official to permit speech-related activity,” citing Shuttlesworth v. City of Birmingham, 394 U.S. 147, 89 S.Ct. 935, 22 L.Ed.2d 162 (1969) and many others. Moreover, the abhorrence or falsity of a doctrine does not justify its suppression. Collin v. Smith, 578 F.2d 1197, 1201 (7th Cir. 1978).
In the case before us, it is not significant that the permits were denied by the City of San Antonio by motion rather than by ordinance; the effect of the council’s action in affirming the manager’s decision was to deny the issuance of any permit to the Iranians and to others. This action, denying all who would exercise their first amendment rights of speech and assembly on the subject of the Shah’s presence is clearly content-based, and “ ‘thus slips from the neutrality of time, place, and circumstance into a concern about content.’ This is never permitted.” Mosley, supra, 408 U.S. at 99, 92 S.Ct. at 2292, citing Kalven, The Concept of the Public Forum: Cox v. Louisiana, 1965 Sup.Ct.Rev. 29. That all would-be demonstrating groups were denied permits by the council’s action without discrimination does not raise the content ban to the level that would pass constitutional muster. The privilege may be regulated, but not, in the guise of regulation, be abridged or denied. Hague v. C.I.O., supra, 307 U.S. 496 at p. 515-16, 59 S.Ct. at 963-64.
The City attempts to meet its “heavy burden” to legitimate its prior restraint by producing evidence of the fears of the city officials of the possibility that an audience hostile to the demonstrations would inflict physical violence on the Iranian demonstrators based upon confrontations between the Iranians and a hostile audience in the previous demonstration on May 10. The City also cites the potential danger to the American hostages then being held in Iran which might result from reprisals if any of the Iranian demonstrators were injured in the demonstration.
The evidence shows that the Iranian demonstrations were to be peaceful and orderly, and any violence directed against the demonstrators would not be retaliated against in kind. The potential danger feared by the city officials was the public disorder created by the hostile audience. Such fears are not a constitutionally permissible factor to be considered in regulating demonstrations. Gregory v. City of Chicago, supra, 394 U.S. 111, 89 S.Ct. 946, 22 L.Ed.2d 134; Cox v. Louisiana, supra, 379 U.S. at 551, 85 S.Ct. at 462; Hague v. C.I.O., supra, 307 U.S. 496 at 516, 59 S.Ct. 954 at 964.3 As one writer aptly observed: “[I]t is unthinkable that such a ‘heckler’s *207veto’ should rise to the dignity of a constitutional principle,” justifying a prior restraint on free speech. Blasi, Prior Restraints on Demonstrations, 68 Mich.L.Rev. 1481, at 1510 (1970). Justice Cadena’s dissent in the court of civil appeals correctly observes that the City’s “evidence” consisted only of speculation about possible reprisals against the fifty hostages. It is clear, however, that “undifferentiated fear of disturbance cannot be the basis of a prior restraint.” Tinker v. Des Moines School District, 393 U.S. 503, 89 S.Ct. 733, 21 L.Ed.2d 731 (1969). Nor does the “clear and present danger” test, first announced by Justice Holmes in Schenck v. United States, 249 U.S. 47, 39 S.Ct. 247, 63 L.Ed. 470 (1919), apply to this case. This doctrine has never been used to justify prior restraints on free speech. Nebraska Press Ass’n v. Stuart, supra. Rather, it has been employed by the courts only in the context of advocacy and incitement as a test of permissible punishment. Brandenburg v. Ohio, 395 U.S. 444, 89 S.Ct. 1827, 23 L.Ed.2d 430 (1969).
It is of great significance here that the City made no effort to resolve the perceived problem by permissible regulation of time, place, and manner. No effort was made to require that the demonstrations of the adversary groups be held at different locations along different routes or at different times.4 The City’s simplistic reflex was to ban completely all expressions by every group on the subject without consideration of any alternatives.
Further, the City seeks to justify the denial of the permit on the basis that the parade ordinance was not introduced into evidence and thus, there is nothing in the record to indicate that the Iranians’ application complied with reasonable discretionary requirements which might be imposed by that ordinance. This argument is without merit as it ignores the overwhelming evidence in the record that the sole basis for the denial of the permit was the views sought to be expressed by the applicants.
The City neither alleged nor attempted to prove that the failure of the Iranians to comply with the parade ordinance was a ground for the denial of the permit. In its answer to the Iranians’ petition, the City alleged only the potential danger to the hostages and possible disruption of public order as justification for the prior restraint. Similarly, there is no evidence in the record indicating that the denial of the permit was predicated on non-compliance with the ordinance.5 The sole question at the temporary injunction proceeding and on appeal has been whether the City’s absolute ban on all public parades encompassing the Iranian question represents an unconstitutional pri- or restraint on free speech so as to inflict an irreparable injury.
*208We hold that in this case the City has failed to meet its “heavy burden” to justify the imposition of a prior restraint on the exercise of free speech.
Finally, we observe that while the court of civil appeals correctly stated that the issuance of a preliminary mandatory injunction is proper only if a mandatory order is necessary to prevent irreparable injury or extreme hardship, the test was improperly applied in this case where a constitutional right of free speech was being stifled by an unconstitutional ban. The court of civil appeals held that the trial court did not abuse its discretion in denying the injunction, presumably because the Shah had already left the United States for Panama. In Southwestern Newspapers Corp. v. Curtis, 584 S.W.2d 362, 365 (Tex.Civ.App.—Amarillo 1979, no writ), the court correctly stated:
In the classical sense, the granting of a temporary injunction is not warranted in the absence of some evidence establishing probable injury if the temporary injunction is not granted.... But the legalism has no efficacy if there is a deprivation of a First Amendment freedom, for any significant denigration of First Amendment rights inflicts irreparable injury ... and constitutes irreparable harm. In brief, “any delay in the exercise of First Amendment rights constitutes an irreparable injury to those seeking such exercise.” . . .
In dealing with the ultimate issue of the trial court’s discretion, the court held at p. 368:
The publisher has plead and shown by nonconflicting evidence the denial of a constitutionally guaranteed right which, as a matter of law, inflicts an irreparable injury. Upon the pleadings and proof, the publisher established its entitlement to the preservation of the status quo pending a trial on the merits of the right to a permanent injunction. Accordingly and absent some other legal ground for the refusal of relief to the publisher, it was a clear abuse of discretion for the trial court to deny a writ of temporary injunction. Cf. Henry v. Greenville Airport Commission, 284 F.2d 631, 633 (4th Cir. 1960), holding that a court has no discretion to deny relief by a temporary injunction where a violation of a constitutional right is clearly established.
The federal courts have also held that the denial of First Amendment rights inflicts irreparable injury. Quaker Action Group v. Hickel, 137 U.S.App.D.C. 176, 181, 421 F.2d 1111, 1116 (1969). See also Shamloo v. Mississippi State Board of Trustees of Institutions of Higher Learning, 620 F.2d 516, 525 (5th Cir. 1980), involving Iranians demonstrating on a college campus during the holding of the fifty hostages in Iran.
We are here constrained to observe that this case should have been tried on the merits in the trial court long before now. As pointed out earlier, the only question before the trial court in a temporary injunction hearing is whether the applicant is entitled to preservation of the status quo of the subject matter of the suit pending trial on the merits. Davis v. Huey, 571 S.W.2d 859, 862 (Tex.1978). The ruling on the temporary injunction may not be used to obtain an advance ruling on the merits; the question to be decided on appeal is whether the trial court abused its discretion in granting or denying the temporary injunction. Houston Independent School District v. City of Houston, 443 S.W.2d 49, 50 (Tex.1969); Transport Co. of Texas v. Robertson Transports, 152 Tex. 551, 261 S.W.2d 549, 552 (1953); McCuiiars v. Van Winkle-Hooker Co., 611 S.W.2d 453, 454-5 (Tex.Civ.App.—Dallas 1980, no writ); Plant Process Equipment, Inc. v. Harris, 579 S.W.2d 53, 55 (Tex.Civ.App.—Houston [14th Dist.] 1979, no writ). Although both parties are ordinarily entitled to a separate trial on the merits on the application for a permanent injunction, the parties may agree to waive the separate trial, combine the two proceedings, and try the temporary and permanent injunction in the same trial. See Houston Belt & T. Ry. Co. v. Texas & New Orleans Railroad, 155 Tex. 407, 289 S.W.2d 217, 219 (1956); Lowe, 6 Texas Practice, Remedies, *209§ 243, p. 236 (1973). If the parties can’t agree, the trial court should advance the trial on the merits so as to eliminate two hearings and two appeals. Southwest Weather Research, Inc. v. Jones, 160 Tex. 104, 327 S.W.2d 417, 421-22 (1959); Crawford Energy, Inc. v. Texas Industries, Inc., 541 S.W.2d 463, 468 (Tex.Civ.App. — Dallas 1976, no writ). This case is illustrative of one where either procedure should have been followed. Not only would judicial resources have been conserved, but equally importantly, the parties would have obtained the speedier resolution of their dispute.
While the procedure suggested is desirable, in a situation such as we have before us, the U.S. Supreme Court has held that First Amendment rights may not be denied during the period of appellate review, normally lasting a year or more to complete, without providing strict procedural safeguards, including immediate appellate review. National Socialist Party v. Village of Skokie, 432 U.S. 43, 97 S.Ct. 2205, 53 L.Ed.2d 96 (1977).
We now turn to the question of the Iranians’ entitlement to a mandatory injunction requiring the City to issue the requested parade permits. Although the permits were requested for a date long past and under conditions which no longer exist, both sides agree in urging that the controversy is not moot.6 We agree. As the United States Supreme Court observed in Nebraska Press Ass’n v. Stuart, supra, 427 U.S. 539 at 546, 96 S.Ct. 2791 at 2797:
[J]urisdiction is not necessarily defeated simply because the order attacked has expired, if the underlying dispute between the parties is one “capable of repetition, yet evading review.”
See also State v. Lodge, 608 S.W.2d 910 (Tex.1980) where this court recognized this principle. Because temporary orders imposing prior restraints upon free speech are by nature short-lived, we hold that the action of the City in this case and upheld by the courts below, is “capable of repetition, yet evading review.” Nebraska Press Ass’n v. Stuart, supra; Southern Pacific Terminal Co. v. I.C.C. and Young, 219 U.S. 498, 515, 31 S.Ct. 279, 283, 55 L.Ed. 310 (1911).
The judgments of the courts below denying the temporary injunction are reversed and the cause is remanded to the trial court for further proceedings consistent with this opinion.
BARROW, J., files dissenting opinion in which GREENHILL, C. J., and McGEE and DENTON, JJ., join.. The City Attorney read the entire motion into the record at the hearing on the temporary injunction, at p. 14.
. The first amendment to the United States Constitution reads:
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
. Several federal district courts have indicated that the fear of a hostile audience is never to be considered in ruling upon permit applications or granting injunctions against demonstrations. See Stacey v. Williams, 306 F.Supp. 963, 977 (N.D.Miss.1969); Hurwitt v. City of Oakland, 247 F.Supp. 995 (N.D.Cal.1965); Williams v. Wallace, 240 F.Supp. 100 (M.D.Ala.1965). We need not go that far.
. The dissenting opinion contains several references to alternatives considered by the City. First, there is no evidence that the city council considered any alternative locations or times. Second, Police Inspector Foresman, the acting Chief of Police when the permit was initially denied, had the power to grant, deny or grant an alternative application. He testified without contradiction that, when passing upon the permit in consultation with the City Manager and the City Attorney, no consideration was given to alternative times or locations. The only reference in the record that the dissent could possibly point to is a hearsay statement by the City Manager relating his conversation with a person who identified himself as Gary Sick, an employee of the National Security Council whose capacity, authority, or expertise is not reflected in the record. Although the City Manager testified that he “stressed” to Gary Sick that he “could think of about five alterna-five actions,” there is no evidence of what they were or that they were revealed to or discussed with anyone else. The enigmatic term “actions” was never explained.
This is not to say that the City did not act in good faith. On the contrary, it is evident that all of the city officials acted in good faith; however, the question before us is not whether good faith was exercised but is a question of law, viz. whether this prior restraint of first amendment rights was permissible under the United States Constitution.
. Even though the City Manager announced at a press conference that one of the reasons for denial was the failure of the Iranians to request a permit fifteen days in advance of the anticipated date of the demonstration, that reason was not asserted by the City in the court proceedings to justify its prior restraint.
. Despite the view expressed in the dissenting opinion that the controversy is moot, neither side agrees. The ban on all expression on both sides of the question still stands. The city’s attorney stated in oral argument that even though the hostages had been released, the City still refuses to issue any permit:
JUDGE: In other words, the sum and substance of that is you still deny the permit?
ATTORNEY: We still deny the permit — we never have offered them a permit.
Furthermore, notwithstanding the assertion in the dissenting opinion, there is no testimony in the record of any city official that anyone now wishing a permit to demonstrate on the Iranian question may now have one; the dissent merely assumes so. In any event, whether permits would now be issued is irrelevant to the constitutional issue at hand because irreparable injury has already occurred.