Opinion of the Court

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.1

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

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1The findings are quoted in full in the opinion of the Supreme Court of Illinois. 177 Ill. 2d 440, 445, 687 N. E. 2d 53, 58 (1997). Some of the evidence supporting these findings is quoted in JUSTICE THOMAS' dissenting opinion. Post, at 100-101.

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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.

66

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 "remain[ing] 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.2

2 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

Opinion of the Court

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 desigindividually or collectively engage in or have engaged in a pattern of criminal gang activity.

4

"(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.

3 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.

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nated areas." Id., at 68a-69a. release the locations of these public.5

II

The city, however, does not "designated areas" to the

During the three years of its enforcement,6 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

8

5 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 & Hillard, 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").

8 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).

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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,10 consolidated and affirmed other pending appeals in accordance with Youkhana,11 and reversed the convictions of respondents Gutierrez, Morales, and others.12 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. 13

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

9 Chicago v. Youkhana, Nos. 93 MCI 293363 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.

10 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.

12 Chicago v. Morales, Nos. 1-93-4039 et al. (Ill. App., Dec. 29, 1995), App. to Pet. for Cert. 37a.

13 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.