[2] Four of the eight defendants—Margaret Papachristou, Betty Calloway, Eugene Eddie Melton, and Leonard Johnson—were charged with "prowling by auto" under the Jacksonville vagrancy ordinance.

[4] Shortly after the defendants' arrest, someone from the police department had called Papachristou's parents and told them she had "been out with a negro.

[6] Heath's co-defendant, who was not one of the eight defendants in the Papachristou case, had been charged with loitering for standing in the driveway; the officers conceded that he was only doing so at their command.

[6] A police witness later testified he had a reputation for being a "thief, narcotics pusher, and generally opprobrious character.

[14] The Court cited a series of Supreme Court precedent standing for the proposition that a law must give fair notice about what conduct it prohibits, including Lanzetta v. New Jersey, Connally v. General Construction Co., and United States v. L. Cohen Grocery Co.[14] The Court reasoned that the Jacksonville ordinance did not give sufficient notice about what was forbidden and that, as written, it could in fact criminalize a variety of innocent activities.

For example, the ordinance forbid "habitually living without visible means of support," which the Court noted may be involuntary.

[15] Similarly, the ordinance labeled as vagrants men who were "able to work but habitually liv[e] upon the earnings of their wives or minor children."

"[16] Far from being criminal, the Court stated, wandering about with no purpose is an activity that is "historically part of the amenities of life as we have known them," and has even been extolled by the likes of Walt Whitman, Vachel Lindsay, and Henry Thoreau.

The Court held that the vagrancy ordinance was also unconstitutionally vague because it gave too much arbitrary power to the police.

("Another aspect of the ordinance's vagueness appears when we focus, not on the lack of notice given a potential offender, but on the effect of the unfettered discretion it places in the hands of the Jacksonville police.

"[19] The Court acknowledged that poor people and minorities would often be the ones implicated by this kind of imprecise law, rendering the equal and even-handed administration of justice impossible.

[20] The Court also rejected the City's argument that the vagrancy ordinance allowed them to "nip crime in the bud" as "too extravagant to deserve extended treatment.

Rather, by declaring Jacksonville's ordinance unconstitutionally vague, the decision imposed clarity requirements on future laws of this type.

Thus, in response to Papachristou, many local governments amended their loitering and vagrancy laws in an attempt to make them constitutional.

[21][22] Cities no longer prohibited simply loitering or wandering around but instead enacted so-called "loitering-plus" laws that imposed additional elements.

"[24] Under the ordinance, a police officer who observed someone whom he or she reasonably believed to be a gang member loitering with one or more other people could order them to disperse.