opinion: Justice Stevens
  announced the judgment of the Court and delivered the opinion of the Court with respect to Parts I, II, and V, and an opinion with respect to Parts III, IV, and VI, in which Justice Souter and Justice Ginsburg join.
  In 1992, the Chicago City Council enacted the Gang Congregation Ordinance, which prohibits “criminal street gang members” from “loitering” with one another or with other persons in any public place. The question presented is whether the Supreme Court of Illinois correctly held that the ordinance violates the Due Process Clause of the Fourteenth Amendment to the Federal Constitution.
  I
  Before the ordinance was adopted, the city council’s Committee on Police and Fire conducted hearings to explore the problems created by the city’s street gangs, and more particularly, the consequences of public loitering by gang members. Witnesses included residents of the neighborhoods where gang members are most active, as well as some of the aldermen who represent those areas. Based on that evidence, the council made a series of findings that are included in the text of the ordinance and explain the reasons for its enactment.
  The council found that a continuing increase in criminal street gang activity was largely responsible for the city’s rising murder rate, as well as an escalation of violent and drug related crimes. It noted that in many neighborhoods throughout the city, “‘the burgeoning presence of street gang members in public places has intimidated many law abiding citizens.’ ” 177 Ill. 2d 440, 445, 687 N. E. 2d 53, 58 (1997). Furthermore, the council stated that gang members “‘establish control over identifiable areas ... by loitering in those areas and intimidating others from entering those areas; and . . . [m]embers of criminal street gangs avoid arrest by committing no offense punishable under existing laws when they know the police are present ....’” Ibid. It further found that “ ‘loitering in public places by criminal street gang members creates a justifiable fear for the safety of persons and property in the area’” and that “ ‘[a]ggressive action is necessary to preserve the city’s streets and other public places so that the public may use such places without fear.’ ” Moreover, the council concluded that the city “‘has an interest in discouraging all persons from loitering in public places with criminal gang members.’” Ibid.
  The ordinance creates a criminal offense punishable by a fine of up to $500, imprisonment for not more than six months, and a requirement to perform up to 120 hours of community service. Commission of the offense involves four predicates. First, the police officer must reasonably believe that at least one of the two or more persons present in a “‘public place’” is a ‘“criminal street gang membe[r].’” Second, the persons must be “‘loitering,’” which the ordinance defines as “ ‘remaining] in any one place with no apparent purpose.’” Third, the officer must then order “‘all’” of the persons to disperse and remove themselves “‘from the area.’” Fourth, a person must disobey the officer’s order. If any person, whether a gang member or not, disobeys the officer’s order, that person is guilty of violating the ordinance. Ibid.
  Two months after the ordinance was adopted, the Chicago Police Department promulgated General Order 92-4 to provide guidelines to govern its enforcement. That order purported to establish limitations on the enforcement discretion of police officers “to ensure that the anti-gang loitering ordinance is not enforced in an arbitrary or discriminatory way.” Chicago Police Department, General Order 92-4, reprinted in App. to Pet. for Cert. 65a. The limitations confine the authority to arrest gang members who violate the ordinance to sworn “members of the Gang Crime Section” and certain other designated officers, and establish detailed criteria for defining street gangs and membership in such gangs. Id., at 66a-67a. In addition, the order directs district commanders to “designate areas in which the presence of gang members has a demonstrable effect on the activities of law abiding persons in the surrounding community,” and provides that the ordinance “will be enforced only within the designated areas.” Id., at 68a-69a. The city, however, does not release the locations of these “designated areas” to the public.
  II
  During the three years of its enforcement, the police issued over 89,000 dispersal orders and arrested over 42,000 people for violating the ordinance. In the ensuing enforcement proceedings, 2 trial judges upheld the constitutionality of the ordinance, but 11 others ruled that it was invalid. In respondent Youkhana’s case, the trial judge held that the “ordinance fails to notify individuals what conduct is prohibited, and it encourages arbitrary and capricious enforcement by police.”
  The Illinois Appellate Court affirmed the trial court’s ruling in the Youkhana case, consolidated and affirmed other pending appeals in accordance with Youkhana, and reversed the convictions of respondents Gutierrez, Morales, and others. The Appellate Court was persuaded that the ordinance impaired the freedom of assembly of nongang members in violation of the First Amendment to the Federal Constitution and Article I of the Illinois Constitution, that it was unconstitutionally vague, that it improperly criminalized status rather than conduct, and that it jeopardized rights guaranteed under the Fourth Amendment.
  The Illinois Supreme Court affirmed. It held “that the gang loitering ordinance violates due process of law in that it is impermissibly vague on its face and an arbitrary restriction on personal liberties.” 177 Ill. 2d, at 447, 687 N. E. 2d, at 59. The court did not reach the contentions that the ordinance “creates a status offense, permits arrests without probable cause or is overbroad.” Ibid.
  In support of its vagueness holding, the court pointed out that the definition of “loitering” in the ordinance drew no distinction between innocent conduct and conduct calculated to cause harm. “Moreover, the definition of ‘loiter’ provided by the ordinance does not assist in clearly articulating the proscriptions of the ordinance.” Id., at 451-452, 687 N. E. 2d, at 60-61. Furthermore, it concluded that the ordinance was “not reasonably susceptible to a limiting construction which would affirm its validity.”
  We granted certiorari, 523 U. S. 1071 (1998), and now affirm. Like the Illinois Supreme Court, we conclude that the ordinance enacted by the city of Chicago is unconstitutionally vague.
  Ill
  The basic factual predicate for the city’s ordinance is not in dispute. As the city argues in its brief, “the very presence of a large collection of obviously brazen, insistent, and lawless gang members and hangers-on on the public ways intimidates residents, who become afraid even to leave their homes and go about their business. That, in turn, imperils community residents’ sense of safety and security, detracts from property values, and can ultimately destabilize entire neighborhoods.” The findings in the ordinance explain that it was motivated by these concerns. We have no doubt that a law that directly prohibited such intimidating conduct would be constitutional, but this ordinance broadly covers a significant amount of additional activity. Uncertainty about the scope of that additional coverage provides the basis for respondents’ claim that the ordinance is too vague.
  We are confronted at the outset with the city’s claim that it was improper for the state courts to conclude that the ordinance is invalid on its face. The city correctly points out that imprecise laws can be attacked on their face under two different doctrines. First, the overbreadth doctrine permits the facial invalidation of laws that inhibit the exercise of First Amendment rights if the impermissible applications of the law are substantial when “judged in relation to the statute’s plainly legitimate sweep.” Broadrick v. Oklahoma, 413 U. S. 601, 612-615 (1973). Second, even if an enactment does not reach a substantial amount of constitutionally protected conduct, it may be impermissibly vague because it fails to establish standards for the police and public that are sufficient to guard against the arbitrary deprivation of liberty interests. Kolender v. Lawson, 461 U. S. 352, 358 (1983).
  While we, like the Illinois courts, conclude that the ordinance is invalid on its face, we do not rely on the overbreadth doctrine. We agree with the city’s submission that the law does not have a sufficiently substantial impact on conduct protected by the First Amendment to render it unconstitutional. The ordinance does not prohibit speech. Because the term “loiter” is defined as remaining in one place “with no apparent purpose,” it is also clear that it does not prohibit any form of conduct that is apparently intended to convey a message. By its terms, the ordinance is inapplicable to assemblies that are designed to demonstrate a group’s support of, or opposition to, a particular point of view. Cf. Clark v. Community for Creative Non-Violence, 468 U. S. 288 (1984); Gregory v. Chicago, 394 U. S. 111 (1969). Its impact on the social contact between gang members and others does not impair the First Amendment “right of association” that our cases have recognized. See Dallas v. Stanglin, 490 U. S. 19, 23-25 (1989).
  On the other hand, as the United States recognizes, the freedom to loiter for innocent purposes is part of the “liberty” protected by the Due Process Clause of the Fourteenth Amendment. We have expressly identified this “right to remove from one place to another according to inclination” as “an attribute of personal liberty” protected by the Constitution. Williams v. Fears, 179 U. S. 270, 274 (1900); see also Papachristou v. Jacksonville, 405 U. S. 156, 164 (1972). Indeed, it is apparent that an individual’s decision to remain in a public place of his choice is as much a part of his liberty as the freedom of movement inside frontiers that is “a part of our heritage” Kent v. Dulles, 357 U. S. 116, 126 (1958), or the right to move “to whatsoever place one’s own inclination may direct” identified in Blaekstone’s Commentaries. 1 W. Blackstone, Commentaries on the Laws of England 130 (1765).
  There is no need, however, to decide whether the impact of the Chicago ordinance on constitutionally protected liberty alone would suffice to support a facial challenge under the overbreadth doctrine. Cf. Aptheker v. Secretary of State, 378 U. S. 500, 515-517 (1964) (right to travel); Planned Parenthood of Central Mo. v. Danforth, 428 U. S. 52, 82-83 (1976) (abortion); Kolender v. Lawson, 461 U. S., at 355, n. 3, 358-360, and n. 9. For it is clear that the vagueness of this enactment makes a facial challenge appropriate. This is not an ordinance that “simply regulates business behavior and contains a scienter requirement.” See Hoffman Estates v. Flipside, Hoffman Estates, Inc., 455 U. S. 489, 499 (1982). It is a criminal law that contains no mens rea requirement, see Colautti v. Franklin, 439 U. S. 379, 395 (1979), and infringes on constitutionally protected rights, see id., at 391. When vagueness permeates the text of such a law, it is subject to facial attack.
  Vagueness may invalidate a criminal law for either of two independent reasons. First, it may fail to provide the kind of notice that will enable ordinary people to understand what conduct it prohibits; second, it may authorize and even encourage arbitrary and discriminatory enforcement. See Kolender v. Lawson, 461 U. S., at 357. Accordingly, we first consider whether the ordinance provides fair notice to the citizen and then discuss its potential for arbitrary enforcement.
  IV
  “It is established that a law fails to meet the requirements of the Due Process Clause if it is so vague and standardless that it leaves the public uncertain as to the conduct it prohibits .. . .” Giaccio v. Pennsylvania, 382 U. S. 399, 402-403 (1966). The Illinois Supreme Court recognized that the term “loiter” may have a common and accepted meaning, 177 Ill. 2d, at 451, 687 N. E. 2d, at 61, but the definition of that term in this ordinance — “to remain in any one place with no apparent purpose” — does not. It is difficult to imagine how any citizen of the city of Chicago standing in a public place with a group of people would know if he or she had an “apparent purpose.” If she were talking to another person, would she have an apparent purpose? If she were frequently checking her watch and looking expectantly down the street, would she have an apparent purpose?
  Since the city cannot conceivably have meant to criminalize each instance a citizen stands in public with a gang member, the vagueness that dooms this ordinance is not the product of uncertainty about the normal meaning of “loitering,” but rather about what loitering is covered by the ordinance and what is not. The Illinois Supreme Court emphasized the law’s failure to distinguish between innocent conduct and conduct threatening harm. Its decision followed the precedent set by a number of state courts that have upheld ordinances that criminalize loitering combined with some other overt act or evidence of criminal intent. However, state courts have uniformly invalidated laws that do not join the term “loitering” with a second specific element of the crime.
  The city’s principal response to this concern about adequate notice is that loiterers are not subject to sanction until after they have failed to comply with an officer’s order to disperse. “[Wjhatever problem is created by a law that criminalizes conduct people normally believe to be innocent is solved when persons receive actual notice from a police order of what they are expected to do.” We find this response unpersuasive for at least two reasons.
  First, the purpose of the fair notice requirement is to enable the ordinary citizen to conform his or her conduct to the law. “No one may be required at peril of life, liberty or property to speculate as to the meaning of penal statutes.” Lanzetta v. New Jersey, 306 U. S. 451, 453 (1939). Although it is true that a loiterer is not subject to criminal sanctions unless he or she disobeys a dispersal order, the loitering is the conduct that the ordinance is designed to prohibit. If the loitering is in fact harmless and innocent, the dispersal order itself is an unjustified impairment of liberty. If the police are able to decide arbitrarily which members of the public they will order to disperse, then the Chicago ordinance becomes indistinguishable from the law we held invalid in Shuttlesworth v. Birmingham, 382 U. S. 87, 90 (1965). Because an officer may issue an order only after prohibited conduct has already occurred, it cannot provide the kind of advance notice that will protect the putative loiterer from being ordered to disperse. Such an order cannot retroactively give adequate warning of the boundary between the permissible and the impermissible applications of the law.
  Second, the terms of the dispersal order compound the inadequacy of the notice afforded by the ordinance. It provides that the officer “shall order all such persons to disperse and remove themselves from the area.” App. to Pet. for Cert. 61a. This vague phrasing raises a host of questions. After such an order issues, how long must the loiterers remain apart? How far must they move? If each loiterer walks around the block and they meet again at the same location, are they subject to arrest or merely to being ordered to disperse again? As we do here, we have found vagueness in a criminal statute exacerbated by the use of the standards of “neighborhood” and “locality.” Connally v. General Constr. Co., 269 U. S. 385 (1926). We remarked in Connolly that “[b]oth terms are elastic and, dependent upon circumstances, may be equally satisfied by areas measured by rods or by miles.” Id., at 395.
  Lack of clarity in the description of the loiterer's duty to obey a dispersal order might not render the ordinance uneon-stitutionally vague if the definition of the forbidden conduct were clear, but it does buttress our conclusion that the entire ordinance fails to give the ordinary citizen adequate notiee of what is forbidden and what is permitted. The Constitution does not permit a legislature to “set a net large enough to catch all possible offenders, and leave it to the courts to step inside and say who could be rightfully detained, and who should be set at large.” United States v. Reese, 92 U. S. 214, 221 (1876). This ordinance is therefore vague “not in the sense that it requires a person to conform his conduct to an imprecise but comprehensible normative standard, but rather in the sense that no standard of conduct is specified at all.” Coates v. Cincinnati, 402 U. S. 611, 614 (1971).
  V
  The broad sweep of the ordinance also violates “ The requirement that a legislature establish minimal guidelines to govern law enforcement.’ ” Kolender v. Lawson, 461 U. S., at 358. There are no such guidelines in the ordinance. In any public place in the city of Chicago, persons who stand or sit in the company of a gang member may be ordered to disperse unless their purpose is apparent. The mandatory language in the enactment directs the police to issue an order without first making any inquiry about their possible purposes. It matters not whether the reason that a gang member and his father, for example, might loiter near Wrigley Field is to rob an unsuspecting fan or just to get a glimpse of Sammy Sosa leaving the ballpark; in either event, if their purpose is not apparent to a nearby police officer, she may— indeed, she “shall” — order them to disperse.
  Recognizing that the ordinance does reach a substantial amount of innocent conduct, we turn, then, to its language to determine if it “necessarily entrusts lawmaking to the moment-to-moment judgment of the policeman on his beat.” Kolender v. Lawson, 461 U. S., at 360 (internal quotation marks omitted). As we discussed in the context of fair notice, see supra, at 56-60, the principal source of the vast discretion conferred on the police in this ease is the definition of loitering as “to remain in any one place with no apparent purpose.”
  As the Illinois Supreme Court interprets that definition, it “provides absolute discretion to police officers to decide what activities constitute loitering.” 177 Ill. 2d, at 457, 687 N. E. 2d, at 63. We have no authority to construe the language of a state statute more narrowly than the construction given by that State’s highest court. “The power to determine the meaning of a statute carries with it the power to prescribe its extent and limitations as well as the method by which they shall be determined.” Smiley v. Kansas, 196 U. S. 447, 455 (1905).
  Nevertheless, the city disputes the Illinois Supreme Court’s interpretation, arguing that the text of the ordinance limits the officer’s discretion in three ways. First, it does not permit the officer to issue a dispersal order to anyone who is moving along or who has an apparent purpose. Second, it does not permit an arrest if individuals obey a dispersal order. Third, no order can issue unless the officer reasonably believes that one of the loiterers is a member of a criminal street gang.
  Even putting to one side our duty to defer to a state court’s construction of the scope of a local enactment, we find each of these limitations insufficient. That the ordinance does not apply to people who are moving — that is, to activity that would not constitute loitering under any possible definition of the term — does not even address the question of how much discretion the police enjoy in deciding which stationary persons to disperse under the ordinance. Similarly, that the ordinance does not permit an arrest until after a dispersal order has been disobeyed does not provide any guidance to the officer deciding whether sueh an order should issue. The “no apparent purpose” standard for making that decision is inherently subjective because its application depends on whether some purpose is “apparent” to the officer on the scene.
  Presumably an officer would have discretion to treat some purposes — perhaps a purpose to engage in idle conversation or simply to enjoy a cool breeze on a warm evening — as too frivolous to be apparent if he suspected a different ulterior motive. Moreover, an officer conscious of the city council’s reasons for enacting the ordinance might well ignore its text and issue a dispersal order, even though an illicit purpose is actually apparent.
  It is true, as the city argues, that the requirement that the officer reasonably believe that a group of loiterers contains a gang member does place a limit on the authority to order dispersal. That limitation would no doubt be sufficient if the ordinance only applied to loitering that had an apparently harmful purpose or effect, or possibly if it only applied to loitering by persons reasonably believed to be criminal gang members. But this ordinance, for reasons that are not explained in the findings of the city council, requires no harmful purpose and applies to nongang members as well as suspected gang members. It applies to everyone in the city who may remain in one place with one suspected gang member as long as their purpose is not apparent to an officer observing them. Friends, relatives, teachers, counselors, or even total strangers might unwittingly engage in forbidden loitering if they happen to engage in idle conversation with a gang member.
  Ironically, the definition of loitering in the Chicago ordinance not only extends its scope to encompass harmless conduct, but also has the perverse consequence of excluding from its coverage much of the intimidating conduct that motivated its enactment. As the city council’s findings demonstrate, the most harmful gang loitering is motivated either by an apparent purpose to publicize the gang’s dominance of certain territory, thereby intimidating nonmembers, or by an equally apparent purpose to conceal ongoing commerce in illegal drugs. As the Illinois Supreme Court has not placed any limiting construction on the language in the ordinance, we must assume that the ordinance means what it says and that it has no application to loiterers whose purpose is apparent. The relative importance of its application to harmless loitering is magnified by its inapplicability to loitering that has an obviously threatening or illicit purpose.
  Finally, in its opinion striking down the ordinance, the Illinois Supreme Court refused to accept the general order issued by the police department as a sufficient limitation on the “vast amount of discretion” granted to the police in its enforcement. We agree. See Smith v. Goguen, 415 U. S. 566, 575 (1974). That the police have adopted internal rules limiting their enforcement to certain designated areas in the city would not provide a defense to a loiterer who might be arrested elsewhere. Nor could a person who knowingly loitered with a well-known gang member anywhere in the city safely assume that they would not be ordered to disperse no matter how innocent and harmless their loitering might be.
  I — I i>
  In our judgment, the Illinois Supreme Court correctly concluded that the ordinance does not provide sufficiently specific limits on the enforcement discretion of the police “to meet constitutional standards for definiteness and clarity.” 177 Ill. 2d, at 459, 687 N. E. 2d, at 64. We recognize the serious and difficult problems testified to by the citizens of Chicago that led to the enactment of this ordinance. “We are mindful that the preservation of liberty depends in part on the maintenance of social order.” Houston v. Hill, 482 U. S. 451, 471-472 (1987). However, in this instance the city has enacted an ordinance that affords too much discretion to the police and too little notice to citizens who wish to use the public streets.
  Accordingly, the judgment of the Supreme Court of Illinois is
  Affirmed.
  The findings are quoted in full in the opinion of the Supreme Court of Illinois. 177 Ill. 2d 440, 445, 687 N. E. 2d 58, 58 (1997). Some of the evidence supporting these findings is quoted in Justice Thomas’ dissenting opinion. Post, at 100-101.
  The ordinance states in pertinent part:
  “(a) Whenever a police officer observes a person whom he reasonably believes to be a criminal street gang member loitering in any public place with one or more other persons, he shall order all such persons to disperse and remove themselves from the area. Any person who does not promptly obey such an order is in violation of this section.
  “(b) It shall be an affirmative defense to an alleged violation of this section that no person who was observed loitering was in fact a member of a criminal street gang.
  “(c) As used in this Section:
  “(1) ‘Loiter’ means to remain in any one place with no apparent purpose.
  “(2) ‘Criminal street gang’ means any ongoing organization, association in fact or group of three or more persons, whether formal or informal, having as one of its substantial activities the commission of one or more of the criminal acts enumerated in paragraph (3), and whose members individually or collectively engage in or have engaged in a pattern of criminal gang activity.
  “(5) ‘Public place’ means the public way and any other location open to the public, whether publicly or privately owned.
  “(e) Any person who violates this Section is subject to a fine of not less than $100 and not more than $500 for each offense, or imprisonment for not more than six months, or both.
  “In addition to or instead of the above penalties, any person who violates this section may be required to perform up to 120 hours of community service pursuant to section 1-4-120 of this Code.” Chicago Municipal Code §8-4-015 (added June 17,1992), reprinted in App. to Pet. for Cert. 61a-63a.
  As the Illinois Supreme Court noted, during the hearings preceding the adoption of the ordinance, “representatives of the Chicago law and police departments informed the city counsel that any limitations on the discretion police have in enforcing the ordinance would be best developed through police policy, rather than placing such limitations into the ordinance itself.” 177 Ill. 2d, at 446, 687 N. E. 2d, at 58-59.
  Presumably, these officers would also be able to arrest all nongang members who violate the ordinance.
  Tr. of Oral Arg. 22-23.
  The city began enforcing the ordinance on the effective date of the general order in August 1992 and stopped enforcing it in December 1995, when it was held invalid in Chicago v. Youkhana, 277 Ill. App. 3d 101, 660 N. E. 2d 34 (1995). Tr. of Oral Arg. 43.
  Brief for Petitioner 16. There were 5,251 arrests under the ordinance in 1993, 15,660 in 1994, and 22,056 in 1995. City of Chicago, R. Daley & T. Hillard, Gang and Narcotic Related Violent Crime: 1993-1997, p. 7 (June 1998).
  The city believes that the ordinance resulted in a significant decline in gang-related homicides. It notes that in 1995, the last year the ordinance was enforced, the gang-related homicide rate fell by 26%. In 1996, after the ordinance had been held invalid, the gang-related homicide rate rose 11%. Pet. for Cert. 9, n. 5. However, gang-related homicides fell by 19% in 1997, over a year after the suspension of the ordinance. Daley & Hil-lard, at 5. Given the myriad factors that influence levels of violence, it is difficult to evaluate the probative value of this statistical evidence, or to reach any firm conclusion about the ordinance’s efficacy. Cf. Harcourt, Reflecting on the Subject: A Critique of the Social Influence Conception of Deterrence, the Broken Windows Theory, and Order-Maintenance Policing New York Style, 97 Mich. L. Rev. 291, 296 (1998) (describing the “hotly contested debate raging among... experts over the causes of the decline in crime in New York City and nationally”).
  See Poulos, Chicago’s Ban on Gang Loitering: Making Sense of Vagueness and Overbreadth in Loitering Laws, 83 Calif. L. Rev. 379, 384, n. 26 (1995).
  Chicago v. Youkhana, Nos. 93 MCI 293368 et al. (Ill. Cir. Ct., Cook Cty., Sept. 29, 1993), App. to Pet. for Cert. 45a. The court also concluded that the ordinance improperly authorized arrest on the basis of a person’s status instead of conduct and that it was facially overbroad under the First Amendment to the Federal Constitution and Art. I, § 5, of the Illinois Constitution. Id., at 59a
  Chicago v. Youkhana, 277 Ill. App. 3d 101, 660 N. E. 2d 34 (1995).
  Chicago v. Ramsey, Nos. 1-93-4125 et al. (Ill. App., Dec. 29, 1995), App. to Pet. for Cert. 39a.
  Chicago v. Morales, Nos. 1-93-4039 et al. (Ill. App., Dec. 29, 1995), App. to Pet. for Cert. 37a
  Chicago v. Youkhana, 277 Ill. App. 3d, at 106, 660 N. E. 2d, at 38; id., at 112, 660 N. E. 2d, at 41; id., at 113, 660 N. E. 2d, at 42.
  “The ordinance defines ‘loiter’ to mean ‘to remain in any one place with no apparent purpose.’ Chicago Municipal Code §8-4-015(c)(l) (added June 17, 1992). People with entirely legitimate and lawful purposes will not always be able to make their purposes apparent to an observing police officer. For example, a person waiting to hail a taxi, resting on a corner during a jog, or stepping into a doorway to evade a rain shower has a perfectly legitimate purpose in all these scenarios; however, that purpose will rarely be apparent to an observer.” 177 Ill. 2d, at 451—452, 687 N. E. 2d, at 60-61.
  It stated: “Although the proscriptions of the ordinance are vague, the city council's intent in its enactment is clear and unambiguous. The city has declared gang members a public menace and determined that gang members are too adept at avoiding arrest for all the other crimes they commit. Accordingly, the dty council crafted an exceptionally broad ordinance which could be used to sweep these intolerable and objectionable gang members from the city streets.” Id., at 458, 687 N. E. 2d, at 64.
  Brief for Petitioner 14.
  In fact the city already has several laws that serve this purpose. See, e.g., Ill. Comp. Stat., ch. 720 §§5/12-6 (1998) (intimidation); 570/405.2 (streetgang criminal drug conspiracy); 147/1 et seq. (Illinois Streetgang Terrorism Omnibus Prevention Act); 5/25-1 (mob action). Deputy Superintendent Cooper, the only representative of the police department at the Committee on Police and Fire hearing on the ordinance, testified that, of the kinds of behavior people had discussed at the hearing, “90 percent of those instances are actually criminal offenses where people, in fact, can be arrested.” Record, Appendix II to plaintiff’s Memorandum in Opposition to Motion to Dismiss 182 (Tr. of Proceedings, Chicago City Council Committee on Police and Fire, May 18, 1992).
  Brief for Petitioner 17.
  See Brief for United States as Amicus Curiae 23: “We do not doubt that, under the Due Process Clause, individuals in this country have significant liberty interests in standing on sidewalks and in other public places, and in traveling, moving, and associating with others.” The city appears to agree, at least to the extent that such activities include “social gatherings.” Brief for Petitioner 21, n. 13. Both Justice Scalia, post, at 83-86 (dissenting opinion), and Justice Thomas, post, at 102-106 (dissenting opinion), not only disagree with this proposition, but also incorrectly assume (as the city does not, see Brief for Petitioner 44) that identification of an obvious liberty interest that is impacted by a statute is equivalent to finding a violation of substantive due process. See n. 35, infra.
  Petitioner cites historical precedent against recognizing what it describes as the “fundamental right to loiter.” Brief for Petitioner 12. While antiloitering ordinances have long existed in this country, their pedigree does not ensure their constitutionality. In 16th-century England, for example, the “ ‘Slavery acts’ ” provided for a 2-year enslavement period for anyone who “‘liveth idly and loiteringly, by the space of three days.’” Note, Homelessness in a Modern Urban Setting, 10 Ford. Urb. L. J. 749, 754, n. 17 (1982). In Papaehristou we noted that many American vagrancy laws were patterned on these “Elizabethan poor laws.” 405 U. S., at 161-162. These laws went virtually unchallenged in this country until attorneys became widely available to the indigent following our decision in Gideon v. Wainwright, 372 U. S. 335 (1963). See Recent Developments, Constitutional Attacks on Vagrancy Laws, 20 Stan. L. Rev. 782,783 (1968). In addition, vagrancy laws were used after the Civil War to keep former slaves in a state of quasi slavery. In 1865, for example, Alabama broadened its vagrancy statute to include “‘any runaway, stubborn servant or child’" and ‘“a laborer or servant who loiters away his time, or refuses to comply with any contract for a term of service without just cause.’” T. Wilson, Black Codes of the South 76 (1965). The Reconstruction-era vagrancy laws had especially harsh consequences on African-American women and children. L. Kerber, No Constitutional Right to be Ladies: Women and the Obligations of Citizenship 50-69 (1998). Neither this history nor the scholarly compendia in Justice Thomas’ dissent, post, at 102-106, persuades us that the right to engage in loitering that is entirely harmless in both purpose and effect is not a part of the liberty protected by the Due Process Clause.
  The freewheeling and hypothetical character of Justice Scalia’s discussion of liberty is epitomized by his assumption that citizens of Chicago, who were once “free to drive about the city” at whatever speed they wished, were the ones who decided to limit that freedom by adopting a speed limit. Post, at 73. History tells quite a different story.
  In 1903, the Illinois Legislature passed “An Act to regulate the speed of automobiles and other horseless conveyances upon the public streets, roads, and highways of the state of Illinois.” That statute, with some exceptions, set a speed limit of 15 miles per hour. See Christy v. Elliott, 216 Ill. 31, 74 N. E. 1035 (1905). In 1900, there were 1,698,575 citizens of Chicago, 1 Twelfth Census of the United States 430 (1900) (Table 6), but only 8,000 ears (both private and commercial) registered in the entire United States. See Ward’s Automotive Yearbook 230 (1990). Even though the number of ears in the country had increased to 77,400 by 1905, ibid., it seems quite clear that it was pedestrians, rather than drivers, who were primarily responsible for Illinois’ decision to impose a speed limit.
  The burden of the first portion of Justice Scalia’s dissent is virtually a facial challenge to the facial challenge doctrine. See post, at 74-83. He first lauds the “clarity of our general jurisprudence” in the method for assessing facial challenges and then states that the clear import of our cases is that, in order to mount a successful facial challenge, a plaintiff must “establish that no set of circumstances exists under which the Act would be valid.” See post, at 78-79 (emphasis deleted); United States v. Salerno, 481 U. S. 739, 745 (1987). To the extent we have consistently articulated a dear standard for facial challenges, it is not the Salerno formulation, which has never been the decisive factor in any dedsion of this Court, including Salerno itself (even though the defendants in that case did not daim that the statute was unconstitutional as applied to them, see id., at 745, n. 3, the Court nevertheless entertained their fadal challenge). Since we, like the Illinois Supreme Court, conclude that vagueness permeates the ordinance, a fadal challenge is appropriate.
  We need not, however, resolve the viability of Salerno’s dictum, because this case comes to us from a state — not a federal — court. When asserting a facial challenge, a party seeks to vindicate not only his own rights, but those of others who may also be adversely impacted by the statute in question. In this sense, the threshold for facial challenges is a species of third party (jus tertii) standing, which we have recognized as a prudential doctrine and not one mandated by Article III of the Constitution. See Secretary of State of Md. v. Joseph H. Munson Co., 467 U. S. 947, 955 (1984). When a state court has reached the merits of a constitutional claim, “invoking prudential limitations on [the respondent’s] assertion of jus tertii would serve no functional purpose.” City of Revere v. Massachusetts Gen. Hospital, 463 U. S. 239, 243 (1983) (internal quotation marks omitted).
  Whether or not it would be appropriate for federal courts to apply the Salerno standard in some cases — a proposition which is doubtful — state courts need not apply prudential notions of standing created by this Court. See ASARCO Inc. v. Kadish, 490 U. S. 605, 618 (1989). Justice Scaxia’s assumption that state courts must apply the restrictive Salerno test is incorrect as a matter of law; moreover it contradicts “essential principles of federalism.” See Dorf, Facial Challenges to State and Federal Statutes, 46 Stan. L. Rev. 235, 284 (1994).
  The Solicitor General, while supporting the city’s argument that the ordinance is constitutional, appears to recognize that the ordinance cannot be read literally without invoking intractable vagueness concerns. “[T]he purpose simply to stand on a corner cannot be an ‘apparent purpose’ under the ordinance; if it were, the ordinance would prohibit nothing at all.” Brief for United States as Amicus Curiae 12-13.
  177 Ill. 2d, at 452, 687 N. E. 2d, at 61. One of the trial courts that invalidated the ordinance gave the following illustration: “Suppose a group of gang members were playing basketball in the park, while waiting for a drug delivery. Their apparent purpose is that they are in the park to play ball. 'Hie actual purpose is that they are waiting for drugs. Under this definition of loitering, a group of people innocently sitting in a park discussing their futures would be arrested, while the ‘basketball players’ awaiting a drug delivery would be left alone.” Chicago v. Youkhana, Nos. 93 MCI 293363 et al. (Ill. Cir. Ct., Cook Cty., Sept. 29, 1993), App. to Pet. for Cert. 48a-49a.
  See, e. g., Tacoma v. Luvene, 118 Wash. 2d 826, 827 P. 2d 1374 (1992) (upholding ordinance criminalizing loitering with purpose to engage in drug-related activities); People v. Superior Court, 46 Cal. 3d 381, 394-395, 758 P. 2d 1046, 1052 (1988) (upholding ordinance criminalizing loitering for the purpose of engaging in or soliciting lewd act).
  See, e. g., State v. Richard, 108 Nev. 626, 627, n. 2, 836 P. 2d 622, 623, n. 2 (1992) (striking down statute that made it unlawful “for any person to loiter or prowl upon the property of another without lawful business with the owner or occupant thereof”).
  Brief for Petitioner 31.
  In this way, the ordinance differs from the statute upheld in Colten v. Kentucky, 407 U. S. 104, 110 (1972). There, we found that the illegality of the underlying conduct was dear. “Any person who stands in a group of persons along a highway where the police are investigating a traffic violation and seeks to engage the attention of an officer issuing a summons should understand that he could be convicted under... Kentucky’s statute if he fails to obey an order to move on.” Ibid.
  “Literally read ... this ordinance says that a person may stand on a public sidewalk in Birmingham only at the whim of any police officer of that city. The constitutional vice of so broad a provision needs no demonstration.” 382 U. S., at 90.
  As we have noted in a similar context: “If petitioners were held guilty of violating the Georgia statute because they disobeyed the officers, this ease falls within the rule that a generally worded statute which is construed to punish conduct which cannot constitutionally be punished is unconstitutionally vague to the extent that it fails to give adequate warning of the boundary between the constitutionally permissible and constitutionally impermissible applications of the statute.” Wright v. Georgia, 373 U. S. 284, 292 (1963).
  This critical fact distinguishes this case from Boos v. Barry, 485 U. S. 312, 329-330 (1988). There, we noted that the text of the relevant statute, read literally, may have been void for vagueness both on notice and on discretionary enforcement grounds. We then found, however, that the Court of Appeals had “provided a narrowing construction that alleviates both of these difficulties.” Ibid.
  It is possible to read the mandatory language of the ordinance and conclude that it affords the police no discretion, since it speaks with the mandatory “shall.” However, not even the city makes this argument, which flies in the face of common sense that all police officers must use some discretion in deciding when and where to enforce city ordinances.
  Justice Thomas’ dissent overlooks the important distinction between this ordinance and those that authorize the police “to order groups of individuals who threaten the public peace to disperse.” See post, at 107.
  Not all of the respondents in this case, for example, are gang members. The city admits that it was unable to prove that Morales is a gang member but justifies his arrest and conviction by the fact that Morales admitted “that he knew he was with criminal street gang members.” Reply Brief for Petitioner 23, n. 14. In fact, 34 of the 66 respondents in this case were charged in a document that only accused them of being in the presence of a gang member. Tr. of Oral Arg. 34, 58.
  This conclusion makes it unnecessary to reach the question whether the Illinois Supreme Court correctly decided that the ordinance is invalid as a deprivation of substantive due process. For this reason, Justice Thomas, see post, at 102-106, and Justice Scalia, see post, at 85-86, are mistaken when they assert that our decision must be analyzed under the framework for substantive due process set out in Washington v. Glucksberg, 521 U. S. 702 (1997).
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