Mr. Justice Douglas
delivered the opinion of the Court.
Petitioner after jury trial was found guilty of disorderly conduct in violation of a city ordinance of Chicago and fined. The case grew out of an address he delivered in an auditorium in Chicago under the auspices of the Christian Veterans of America. The' meeting commanded considerable public attention. The auditorium was filled to capacity with over eight hundred persons present. Others were turned away. Outside of the auditorium a crowd of about one thousand persons gathered to protest against the meeting. A. cordon of policemen was assigned -to the meeting to maintain order; but they were not able to prevent several disturbances. The crowd outside was angry and turbulent.
Petitioner in his speech condemned the conduct of the crowd outside and vigorously, if not viciously, criticized various political and racial groups whose activities he denounced as inimical to the nation’s welfare.
The trial court charged that “breach of the peace” consists of any “misbehavior which violates the public peace and decorum”; and that the “misbehavior may constitute a breach of the peace if it stirs the public to anger, invites „ dispute, brings about a condition of unrest, or creates a disturbance, or if it molests the inhabitants in the enjoyment of peace and quiet- by arousing alarm.” Petitioner did not take exception to that instruction. But he maintained at all times that’ the ordinance as applied to his conduct violated his right of free speech under the Federal Constitution. The judgment of conviction was affirmed by the Illinois Appellate Court (332 Ill. App. 17, 74 N. E. 2d 45) and by the Illinois Supreme Court. 396 Ill. 41, 71 N. E. 2d 2; 400 Ill. 23, 79 N. E. 2d 39. The' case is here on a petition for certiorari-which we granted ■because of the importance of the question presented.
- The argument here has been focused on the issue of whether the content of petitioner’s speech was composed of derisive, fighting words, which' carried it outside the scope of the constitutional guarantees. See Chaplinsky v. New Hampshire, 315 U. S. 568; Cantwell v. Connecticut, 310 U. S. 296, 310. We' do not reach that question, for there is a preliminary question that is dispositive of the case.
As we have noted, the statutory words “breach of the peace” were defined in instructions to the jury to include speech which “stirs the public to anger, invites dispute, brings about a condition of unrest, or creates a disturbance . . . .” That construction of the ordinance is a ruling on a question of state law that is- as binding on us as though the precise words had been written into the ordinance. See Hebert v. Louisiana, 272 U. S. 312, 317; Winters v. New York, 333 U. S. 507, 514.
The vitality of civil and political institutions in our society depends on free discussion. As Chief Justice Hughes wrote in De Jonge v. Oregon, 299 U. S. 353, 365, it is only through free debate and free exchange of ideas that government remains responsive to the will of the people and peaceful change is effected. The right to speak freely and to promote diversity of ideas and programs is therefore one of the chief distinctions that sets us apart from totalitarian regimes.
Accordingly a function of free speech'under our system of government is to invite dispute. It may indeed best serve its high purpose when it induces a condition of unrest, creates dissatisfaction with conditions as they are, or even stirs people to anger. Speech is often provocative and challenging. It may strike at prejudices and' preconceptions and have' profound unsettling effect's as it presses for acceptance of an idea. That is why freedom of speech, though not absolute, Chaplinsky v. New Hampshire, supra, pp. 571-572, is nevertheless protected against censorship or punishment, unless shown likely to produce a clear and present danger of a serious substantive evil that rises far above public inconvenience, annoyance, or unrest. See Bridges v. California, 314 U. S. 252, 262; Craig v. Harney, 331 U. S. 367, 373. There is.no room under our Constitution for a more restrictive view. For the alternative would lead to standardization of ideas either by legislatures, courts, or dominant political or community groups.
The ordinance as construed by the trial court seriously invaded this province. It permitted conviction of petitioner if his speech stirred people to anger, invited public dispute, or brought about a condition of unrest. A conviction resting on any of those grounds may not stand.
The fact that petitioner took no exception to the instruction is immaterial. No exception to the instructions was taken in Stromberg v. California, 283 U. S. 359. But a judgment of conviction based on a general verdict under a state statute was set aside in that case, because one part of the statute was Unconstitutional. The statute had been challenged as unconstitutional and the instruction was framed in its language. The Court held that the attack on the statute as a whole was equally an attack on each of its individual parts. Since the verdict was a general one and did not specify the ground upon which it rested, it could not be sustained. For one part, of the statute was unconstitutional and it could not be determined that the defendant was not convicted under that part.
The principle of that case controls this one. As we have said, the gloss which Illinois placed on the ordinance gives-it’a meaning and application which are conclusive on us. We need not consider whether as construed it is defective in its entirety. As construed and applied it at least contains parts that are unconstitutional. The verdict was a general one; and we do not know on this record but what it may rest on the invalid clauses.
The. statute as construed in the charge to the jury was passed on by the Illinois courts and sustained by them over the objection that as so read it violated the Fourteenth Amendment. The fact that the parties did not dispute its construction makes the adjudication no less ripe for our review, as the Stromberg decision indicates. We can only take the statute as the state courts read it. From our point of view it is immaterial whether the state law question as to its meaning was controverted or accepted. The pinch of the statute is in its application. It is that question which the petitioner has brought here. To say therefore that the question on this phase of the case is whether the trial judge gave a wrong charge is wholly to misconceive the issue.
But it is said that throughout the appellate proceedings the Illinois courts assumed that the only conduct punishable and punished under the ordinance was conduct constituting “fighting words.” That emphasizes, however, the importance of the rule of the Stromberg case. Petitioner was not convicted under a statute so narrowly construed. For all anyone knows he was convicted under the parts of the ordinance (as construed) which, for example, make it an offense merely to invite dispute or to bring about a condition of unrest. We cannot avoid that issue by saying that all Illinois did was to measure petitioner’s conduct, not the ordinance, against the Constitution. Petitioner raised both points — that his speech was protected .by the Constitution; that the inclusion of his speech within the ordinance was a violation of the Constitution. We would, therefore, strain at technicalities to conclude that the. constitutionality of the ordinance-as construed and applied to petitioner was not before the Illinois courts. The record makes- clear that petitioner at all times challenged the constitutionality of the ordinance as construed and applied to him.
Reversed.
“A11 persons who shall .make, aid, countenance, or assist in'making any improper noise, riot, disturbance, breach of the peace, or diversion tending to a breach of the peace, within the limits of the city . . . shall be deemed guilty of disorderly conduct, and upon conviction thereof, shall be severally., fined not less than one dollar nor more than two hundred dollars for each offense.” Municipal Co.de of Chicago, 1939, § 193-1.