MR. Justice Brennan
delivered the opinion of the Court.
The appellants are honorably discharged veterans of World War II who claimed the veterans’ property-tax exemption provided by Art. XIII, § 1%, of the California Constitution. Under California law applicants for such exemption must annually complete a standard form of application and file it with the local assessor. The form was revised in 1954 to add an oath by the applicant: “I do not advocate the overthrow of the Government of the United States or of the State of California by force or violence or other unlawful means, nor advocate the support of a foreign government against the United States in event of hostilities.” Each refused to subscribe the oath and struck it from the form which he executed and filed for the tax year 195A-1955. Each contended that the exaction of the oath as a condition of obtaining a tax exemption was forbidden by the Federal Constitution. The respective assessors denied the exemption solely for the refusal to execute the oath. The Supreme Court of California sustained the assessors’ actions against the appellants’ claims of constitutional invalidity. We noted probable jurisdiction of the appeals. 355 U. S. 880.
Article XX, § 19, of the California Constitution, adopted at the general election of November 4, 1952, provides as follows:
“Notwithstanding any other provision of this Constitution, no person or organization which advocates the overthrow of the Government of the United States or the State by force or violence or other unlawful means or who advocates the support of a foreign government against the United States in the event of hostilities shall:
“(b) Receive any exemption from any tax imposed by this State or any county, city or county, city, district, political subdivision, authority, board, bureau, commission or other public agency of this State.
“The Legislature shall enact such laws as may be necessary to enforce the provisions of this section.”
To effectuate this constitutional amendment the California Legislature enacted § 32 of the Revenue and Taxation Code, which requires the claimant, as a prerequisite to qualification for any property-tax exemption, to sign a statement on his tax return declaring that he does not engage in the activities described in the constitutional amendment. The California Supreme Court held that this declaration, like other statements required of those filing tax returns, was designed to relieve the tax assessor of “the burden ... of ascertaining the facts with reference to tax exemption claimants.” 48 Cal. 2d 419, 432, 311 P. 2d 508, 515. The declaration, while intended to provide a means of determining whether a claimant qualifies for the exemption under the constitutional amendment, is not conclusive evidence of eligibility. The assessor has the duty of investigating the facts underlying all tax liabilities and is empowered by § 454 of the Code to subpoena taxpayers for the purpose of questioning them about statements they have furnished. If the assessor believes that the claimant is not qualified in any respect, he may deny the exemption and require the claimant, on judicial review, to prove the incorrectness of the determination. In other words, the factual determination whether the taxpayer is eligible for the exemption under the constitutional amendment is made in precisely the same manner as the determination of any other fact bearing on tax liability.
The appellants attack these provisions, inter alia, as denying them freedom of speech without the procedural safeguards required by the Due Process Clause of the Fourteenth Amendment.
I.
It cannot be gainsaid that a discriminatory denial of a tax exemption for engaging in speech is a limitation on free speech. The Supreme Court of California recognized that these provisions were limitations on speech but concluded that “by no standard can the infringement upon freedom of speech imposed by section 19 of article XX be deemed a substantial one.” 48 Cal. 2d 419, 440, 311 P. 2d 508, 521. It is settled that speech can be effectively limited by the exercise of the taxing power. Grosjean v. American Press Co., 297 U. S. 233. To deny an exemption to claimants who engage in certain forms of speech is in effect to penalize them for such speech. Its deterrent effect is the same as if the State were to fine them for this speech. The appellees are plainly mistaken in their argument that, because a tax exemption is a “privilege” or “bounty,” its denial may not infringe speech. This contention did not prevail before the California courts, which recognized that conditions imposed upon the granting of privileges or gratuities must be “reasonable.” It has been said that Congress may not by withdrawal of mailing privileges place limitations upon the freedom of speech which if directly attempted would be unconstitutional. See Hannegan v. Esquire, Inc., 327 U. S. 146, 156; cf. Milwaukee Publishing Co. v. Burleson, 255 U. S. 407, 430-431 (Brandeis, J., dissenting). This Court has similarly rejected the contention that speech was not abridged when the sole restraint on its exercise was withdrawal of the opportunity to invoke the facilities of the National Labor Relations Board, American Communications Assn. v. Douds, 339 U. S. 382, 402, or the opportunity for public employment, Wieman v. Updegraff, 344 U. S. 183. So here, the denial of a tax exemption for engaging in certain speech necessarily will have the effect of coercing the claimants to refrain from the proscribed speech. The denial is “frankly aimed at the suppression of dangerous ideas.” American Communications Assn. v. Douds, supra, at 402.
The Supreme Court of California construed the constitutional amendment as denying the tax exemptions only to claimants who engage in speech which may be criminally punished consistently with the free-speech guarantees of the Federal Constitution. The court defined advocacy of “the overthrow of the Government ... by force or violence or other unlawful means” and advocacy of “support of a foreign government against the United States in event of hostilities” as reaching only conduct which may constitutionally be punished under either the California Criminal Syndicalism Act, Cal. Stat. 1919, c. 188, see Whitney v. California, 274 U. S. 357, or the Federal Smith Act, 18 U. S. C. § 2385. 48 Cal. 2d, at 428, 311 P. 2d, at 513. It also said that it would apply the standards set down by this Court in Dennis v. United States, 341 U. S. 494, in ascertaining the circumstances which would justify punishing speech as a crime. Of course the constitutional and statutory provisions here involved must be read in light of the restrictive construction that the California court, in the exercise of its function of interpreting state law, has placed upon them. For the purposes of this case we assume without deciding that California may deny tax exemptions to persons who engage in the proscribed speech for which they might be fined or imprisoned.
II.
But the question remains whether California has chosen a fair method for determining when a claimant is a member of that class to which the California court has said the constitutional and statutory provisions extend. When we deal with the complex of strands in the web of freedoms which make up free speech, the operation and effect of the method by which speech is sought to be restrained must be subjected to close analysis and critical judgment in the light of the particular circumstances to which it is applied. Kingsley Books, Inc., v. Brown, 354 U. S. 436, 441-442; Near v. Minnesota, 283 U. S. 697; cf. Cantwell v. Connecticut, 310 U. S. 296, 305; Joseph Burstyn, Inc., v. Wilson, 343 U. S. 495; Winters v. New York, 333 U. S. 507; Niemotko v. Maryland, 340 U. S. 268; Staub v. City of Baxley, 355 U. S. 313.
To experienced lawyers it is commonplace that the outcome of a lawsuit — and hence the vindication of legal rights — depends more often on how the factfinder appraises the facts than on a disputed construction of a statute or interpretation of a line of precedents. Thus the procedures by which the facts of the case are determined assume an importance fully as great as the validity of the substantive rule of law to be applied. And the more important the rights at stake the more important must be the procedural safeguards surrounding those rights. Cf. Powell v. Alabama, 287 U. S. 45, 71. When the State undertakes to restrain unlawful advocacy it must provide procedures which are adequate to safeguard against infringement of constitutionally protected rights — rights which we value most highly and which are essential to the workings of a free society. Moreover r since only considerations of the greatest urgency can justify restrictions on speech, and since the validity of a restraint on speech in each case depends on careful analysis of the particular circumstances, cf. Dennis v. United States, supra; Whitney v. California, supra, the procedures by which the facts of the case are adjudicated are of special importance and the validity of the restraint may turn on the safeguards which they afford. Compare Kunz v. New York, 340 U. S. 290, with Feiner v. New York, 340 U. S. 315. It becomes essential, therefore, to scrutinize the procedures by which California has sought to restrain speech.
The principal feature of the California procedure, as the appellees themselves point out, is that the appellants, “as taxpayers under state law, have the affirmative burden of proof, in Court as well as before the Assessor. . . . [I] t is their burden to show that they are proper persons to qualify under the self-executing constitutional provision for the tax exemption in question — i. e., that they are not persons who advocate the overthrow of the government of the United States or the State by force or violence or other unlawful means or who advocate the support of a foreign government against the United States in the event of hostilities. . . . [T]he burden is on them to produce evidence justifying their claim of exemption.” Not only does the initial burden of bringing forth proof of nonadvocacy rest on the taxpayer, but throughout the judicial and administrative proceedings the burden lies on the taxpayer of persuading the assessor, or the court, that he falls outside the class denied the tax exemption. The declaration required by § 32 is but a part of the probative process by which the State seeks to determine which taxpayers fall into the proscribed category. Thus the declaration cannot be regarded as having such independent significance that failure to sign it precludes review of the validity of the procedure of which it is a part. Cf. Staub v. City of Baxley, supra, at 318-319. The question for decision, therefore, is whether this allocation of the burden of proof, on an issue concerning freedom of speech, falls short of the requirements of due process.
It is of course within the power of the State to regulate procedures under which its laws are carried out, including the burden of producing evidence and the burden of persuasion, “unless in so doing it offends some principle of justice so rooted in the traditions and conscience of our people as to be ranked as fundamental.” Snyder v. Massachusetts, 291 U. S. 97, 105. “[O]f course the legislature may go a good way in raising . . . [presumptions] or in changing the burden of proof, but there are limits. ... [ I ] t is not within the province of a legislature to declare an individual guilty or presumptively guilty of a crime.” McFarland v. American Sugar Refining Co., 241 U. S. 79, 86. The legislature cannot “place upon all defendants in criminal cases the burden of going forward with the evidence. [It cannot] validly command that the finding of an indictment, or mere proof of the identity of the accused, should create a presumption of the existence of all the facts essential to guilt. This is not permissible.” Tot v. United States, 319 U. S. 463, 469. Of course, the burden of going forward with the evidence at some stages of a criminal trial may be placed on the defendant, but only after the State has “proved enough to make it just for the defendant to be required to repel what has been proved with excuse or explanation, or at least that upon a balancing of convenience or of the opportunities for knowledge the shifting of the burden will be found to be an aid to the accuser without subjecting the accused to hardship or oppression.” Morrison v. California, 291 U. S. 82, 88-89. In civil cases too this Court has struck down state statutes unfairly shifting the burden of proof. Western & A. R. Co. v. Henderson, 279 U. S. 639; cf. Mobile, J. & K. C. R. Co. v. Turnipseed, 219 U. S. 35, 43.
It is true that due process may not always compel the full formalities of a criminal prosecution before criminal advocacy can be suppressed or deterred, but it is clear that the State which attempts to do so must provide procedures amply adequate to safeguard against invasion speech which the Constitution protects. Kingsley Books, Inc., v. Brown, supra. It is, of course, familiar practice in the administration of a tax program for the taxpayer to carry the burden of introducing evidence to rebut the determination of the collector. Phillips v. Dime Trust Co., 284 U. S. 160, 167; Brown v. Helvering, 291 U. S. 193, 199. But while the fairness of placing the burden of proof on the taxpayer in most circumstances is recognized, this Court has not hesitated to declare a summary tax-collection procedure a violation of due process when the purported tax was shown to be in reality a penalty for a crime. Lipke v. Lederer, 259 U. S. 557; cf. Helwig v. United States, 188 U. S. 605. The underlying rationale of these cases is that where a person is to suffer a penalty for a crime he is entitled to greater procedural safeguards than when only the amount of his tax liability is in issue. Similarly it does not follow that because only a tax liability is here involved, the ordinary tax assessment procedures are adequate when applied to penalize speech.
It is true that in the present case the appellees purport to do no more than compute the amount of the taxpayer’s liability in accordance with the usual procedures, but in fact they have undertaken to determine whether certain speech falls within a class which constitutionally may be curtailed. As cases decided in this Court have abundantly demonstrated, the line between speech unconditionally guaranteed and speech which may legitimately be regulated, suppressed, or punished is finely drawn. Thomas v. Collins, 323 U. S. 516; cf. Yates v. United States, 354 U. S. 298. The separation of legitimate from illegitimate speech calls for more sensitive tools than California has supplied. In all kinds of litigation it is plain that where the burden of proof lies may be decisive of the outcome. Cities Service Oil Co. v. Dunlap, 308 U. S. 208; United States v. New York, N. H. & H. R. Co., 355 U. S. 253; Sampson v. Channell, 110 F. 2d 754, 758. There is always in litigation a margin of error, representing error in factfinding, which both parties must take into account. Where one party has at stake an interest of transcending value — as a criminal defendant his liberty — this margin of error is reduced as to him by the process of placing on the other party the burden of producing a sufficiency of proof in the first instance, and of persuading the factfinder at the conclusion of the trial of his guilt beyond a reasonable doubt. Due process commands that no man shall lose his liberty unless the Government has borne the burden of producing the evidence and convincing the factfinder of his guilt. Tot v. United States, supra. Where the transcendent value of speech is involved, due process certainly requires in the circumstances of this case that the State bear the burden of persuasion to show that the appellants engaged in criminal speech. Cf. Kingsley Books, Inc., v. Brown, supra.
The vice of the present procedure is that, where particular speech falls close to the line separating the lawful and the unlawful, the possibility of mistaken factfinding— inherent in all litigation — will create the danger that the legitimate utterance will be penalized. The man who knows that he must bring forth proof and persuade another of the lawfulness of his conduct necessarily must steer far wider of the unlawful zone than if the State must bear these burdens. This is especially to be feared when the complexity of the proofs and the generality of the standards applied, cf. Dennis v. United States, supra, provide but shifting sands on which the litigant must maintain his position. How can a claimant whose declaration is rejected possibly sustain the burden of proving the negative of these complex factual elements? In practical operation, therefore, this procedural device must necessarily produce a result which the State could not command directly. It can only result in a deterrence of speech which the Constitution makes free. “It is apparent that a constitutional prohibition cannot be transgressed indirectly by the creation of a statutory presumption any more than it can be violated by direct enactment. The power to create presumptions is not a means of escape from constitutional restrictions.” Bailey v. Alabama, 219 U. S. 219, 239.
The appellees, in controverting this position, rely on cases in which this Court has sustained the validity of loyalty oaths required of public employees, Garner v. Board of Public Works, 341 U. S. 716, candidates for public office, Gerende v. Board of Supervisors, 341 U. S. 56, and officers of labor unions, American Communications Assn. v. Douds, supra. In these cases, however, there was no attempt directly to control speech but rather to protect, from an evil shown to be grave, some interest clearly within the sphere of governmental concern. The purpose of the legislation sustained in the Douds case, the Court found, was to minimize the danger of political strikes disruptive of interstate commerce by discouraging labor unions from electing Communist Party members to union office. While the Court recognized that the necessary effect of the legislation was to discourage the exercise of rights protected by the First Amendment, this consequence was said to be only indirect. The congressional purpose was to achieve an objective other than restraint on speech. Only the method of achieving this end touched on protected rights and that only tangentially. The evil at which Congress had attempted to strike in that case was thought sufficiently grave to justify limited infringement of political rights. Similar considerations governed the other cases. Each case concerned a limited class of persons in or aspiring to public positions by virtue of which they could, if evilly motivated, create serious danger to the public safety. The principal aim of those statutes was not to penalize political beliefs but to deny positions to persons supposed to be dangerous because the position might be misused to the detriment of the public. The present legislation, however, can have no such justification. It purports to deal directly°with speech and the expression of political ideas. “Encouragement to loyalty to our institutions ... [is a doctrine] which the state has plainly promulgated and intends to foster.” 48 Cal. 2d, at 439, 311 P. 2d, at 520. The State argues that veterans as a class occupy a position of special trust and influence in the community, and therefore any veteran who engages in the proscribed advocacy constitutes a special danger to the State. But while a union official or public employee may be deprived of his position and thereby removed from the place of special danger, the State is powerless to erase the service which the veteran has rendered his country; though he be denied a tax exemption, he remains a veteran. The State, consequently, can act against the veteran only as it can act against any other citizen, by imposing penalties to 'deter the unlawful conduct.
Moreover, the oaths required in those cases performed a very different function from the declaration in issue here. In the earlier cases it appears that the loyalty oath, once signed, became conclusive evidence of the facts attested so far as the right to office was concerned. If the person took the oath he retained his position. The oath was not part of a device to shift to the officeholder the burden of proving his right to retain his position. The signer, of course, could be prosecuted for perjury, but only in accordance with the strict procedural safeguards surrounding such criminal prosecutions. In the present case, however, it is clear that the declaration may be accepted or rejected on the basis of incompetent information or no information at all. It is only a step in a process throughout which the taxpayer must bear the burden of proof.
Believing that the principles of those cases have no application here, we hold that when the constitutional right to speak is sought to be deterred by a State’s general taxing program due process demands that the speech be unencumbered until the State comes forward with sufficient proof to justify its inhibition. The State clearly has no such compelling interest at stake as to justify a short-cut procedure which must inevitably result in suppressing protected speech. Accordingly, though the validity of § 19 of Art. XX of the State Constitution be conceded arguendo, its enforcement through procedures which place the burdens of proof and persuasion on the taxpayer is a violation of due process. It follows from this that appellants could not be required to execute the declaration as a condition for obtaining a tax exemption or as a condition for the assessor proceeding further in determining whether they were entitled to such an exemption. Since the entire statutory procedure, by placing the burden of proof on the claimants, violated the requirements of due process, appellants were not obliged to take the first step in such a procedure.
The judgments are reversed and the causes are remanded for further proceedings not inconsistent with this opinion.
Reversed and remanded.
Mr. Justice Burton concurs in the result.
The Chief Justice took no part in the consideration or decision of this case.
Appellant in No. 483 sued for declaratory relief in the Superior Court of Contra Costa County. Five judges sitting en banc held that both § 19 of Art. XX and § 32 of the Revenue and Taxation Code were invalid under the Fourteenth Amendment as restrictions on freedom of speech. The California Supreme Court reversed. 48 Cal. 2d 903, 311 P. 2d 546.
Appellant in No. 484 sued in the Superior Court for the City and County of San Francisco to recover taxes paid under protest and for declaratory relief. The court upheld the validity of both the constitutional provision and § 32 of the Code. The Supreme Court affirmed. 48 Cal. 2d 472, 311 P. 2d 544.
In both cases the Supreme Court adopted the reasoning of its opinion in First Unitarian Church v. County of Los Angeles, 48 Cal. 2d 419, 311 P. 2d 508, in which identical issues are discussed at length. Hereinafter we will refer to that opinion as expressing the views of the California Supreme Court in the present cases.
Section 32 provides:
“Any statement, return, or other document in which is claimed any exemption, other than the householder’s exemption, from any property tax imposed by this State or any county, city or county, city, district, political subdivision, authority, board, bureau, commission or other public agency of this State shall contain a declaration that the person or organization making the statement, return, or other document does not advocate the overthrow of the Government of the United States or of the State of California by force or violence or other unlawful means nor advocate the support of a foreign government against the United States in event of hostilities. If any such statement, return, or other document does not contain such declaration, the person or organization making such statement, return, or other document shall not receive any exemption from the tax to which the statement, return, or other document pertains. Any person or organization who makes such declaration knowing it to be false is guilty of a felony. This section shall be construed so as to effectuate the purpose of Section 19 of Article XX of the Constitution.”
This contention was raised in the complaint and is argued in the brief in this Court. The California Supreme Court rejected the contention as without merit. 48 Cal. 2d 472, 475, 311 P. 2d 544, 545-546.
Appellants also argue that these provisions are invalid (1) as invading liberty of speech protected by the Due Process Clause of the Fourteenth Amendment; (2) as denying equal protection because the oath is required only as to property-tax and corporation-income-tax exemptions, but not as to the householder’s personal-income-tax, gift-tax, inheritance-tax, or sales-tax exemptions; and (3) as violating the Supremacy Clause because this legislation intrudes in a field of exclusive federal control, Pennsylvania v. Nelson, 350 U. S. 497. Our disposition of the cases makes considerations of these questions unnecessary.
The California Supreme Court construed these provisions as inapplicable to mere belief. On oral argument counsel for the taxing authorities further conceded that the provisions would not apply in the case of advocacy of mere "abstract doctrine.” See Yates v. United States, 354 U. S. 298, 312-327.
Appellants contend that under this Court’s decision in Pennsylvania v. Nelson, 350 U. S. 497, the State can no longer enforce its criminal statutes aimed at subversion. We need not decide whether this contention is sound; nor need we consider whether, if it is, it follows that California cannot deny tax exemptions to those who in fact are in violation of the federal and state sedition laws.
The California Supreme Court held that § 19 of Art. XX of the State Constitution was in effect self-executing. “[U]nder the tax laws of the state wholly apart from section 32 it is the duty of the assessor to ascertain the facts with reference to the taxability or exemption from taxation of property within his jurisdiction. And it is also the duty of the property owner to cooperate with the assessor and assist him in the ascertainment of these facts by declarations under oath.” 48 Cal. 2d, at 430, 311 P. 2d, at 514-515.
In all events, if the assessor “is satisfied from his investigations that the exemption should not be allowed he may assess the property as not exempt and if contested compel a determination of the facts in a suit to recover the tax paid under protest. In such a case it would be necessary for the claimant to allege and prove facts with reference to the nature, extent and character of the property which would justify the exemption and compliance with all valid regulations in the presentation and prosecution of the claim. In any event it is the duty of the assessor to ascertain the facts from any legal source available. In performing this task he is engaged in the assembly of facts which are to serve as a guide in arriving at his conclusion whether an exemption should or should not be allowed. That conclusion is in no wise a final determination that the claimant belongs to a class proscribed by section 19 of article XX or is.guilty of any activity there denounced. The presumption of innocence available to all in criminal prosecutions does not in a ease such as this relieve or prevent the assessor from making the investigation enjoined upon him by law to see that exemptions are not improperly' allowed. His administrative determination is not binding on the tax exemption claimant but it is sufficient to authorize him to tax the property as nonexempt and to place the burden on the claimant to test the validity of his administrative determination in an action at law.” 48 Cal. 2d, at 431-432, 311 P. 2d, at 515.
It is suggested that the opinion of the California Supreme Court be read as holding that “the filing, whether the oath be true or false, would conclusively establish the taxpayer’s eligibility for an exemption.” But the California court expressly states that “it is the duty of the assessor to see that exemptions are not allowed contrary to law and this of course includes those which are contrary to the prohibitions provided for in section 19 of article XX,” 48 Cal. 2d 419, 431, 311 P. 2d 508, 515, and that the “mandatory and prohibitory” provision of § 19 of Art. XX “applies to all tax exemption claimants.” 48 Cal. 2d, at 428, 311 P. 2d, at 513. Indeed, the tax authorities of California themselves point out that the signing of the declaration is not conclusive of the right to the tax exemption. The brief of the taxing authorities in the companion case, First Unitarian Church v. County of Los Angeles, post, p. 545, states, “Section 32 is an evidentiary provision. Its purpose and effect are to afford to the Assessor information to guide his compliance with and his enforcement of the Constitution’s prohibition . . . .” (Emphasis supplied.)
It is also suggested that this Court construe the California legislation contrary to the clearly expressed construction of the California Supreme Court and thus avoid decision of the question of procedural due process. But this construction would not avoid decision of constitutional questions but rather would create the necessity for decision of the broader constitutional question of the validity of § 19 of Art. XX. A more fundamental objection to the suggestion, of course, is that it does violence to the basic constitutional principle that the construction of state laws is the exclusive responsibility of the state courts.
Significantly, the New York statute which this Court upheld in Adler v. Board of Education, 342 U. S. 485, provided that public-school teachers could be dismissed on security grounds only after a hearing at which the official pressing the charges sustained his burden of proof by a fair preponderance of the evidence.