Because of the rise in rates of juvenile crime from the 1980s through the mid-1990s, many of the nation's jurisdictions imposed youth curfews. A 2000 survey of 490 cities by the National League of Cities found that 69% (337) had nighttime curfews and 14% (68) had daytime curfews. Thirty-five of the cities surveyed reported that they were considering adopting a curfew.

Most curfew laws restrict juveniles to their home or property between the hours of 11P.M. and 6 A.M. weekdays, allowing them to stay out later on weekends. The laws allow exceptions for young people going to and from school, church events, or work, and for youths who have a family emergency or are accompanied by their parents. Critics of such ordinances argue that they violate the equal protection clause of the U.S. Constitution and abridge parental rights. The critics also argue that no studies have proven the effectiveness of curfew laws.

In 1994 the U.S. Supreme Court let stand a lower court ruling that a Dallas, Texas, curfew law was constitutional. But in 2003 the Washington State Supreme Court struck down the city of Sumner's curfew law (Walsh v. City of Sumner [No. 71451–7]). The court ruled that Sumner's curfew ordinance, which makes it unlawful for juveniles to "remain" in a public place during certain hours, is unconstitutionally vague because "it does not provide 'ascertainable standards for locating the line between innocent and unlawful behavior.'" The court noted that "it may be difficult for a city to draft a curfew ordinance that is not unconstitutionally vague" because "curfew ordinances attempt to make activities that are normally considered innocent, unlawful, i.e., walking, driving, going to the store." And in July 2004 the U.S. District Court in the Southern District of Indiana issued an injunction prohibiting enforcement of Indiana's juvenile curfew law.

The U.S. Conference of Mayors conducted a 1997 survey of 276 cities with a nighttime youth curfew and asked city officials how they felt about it. Officials in nine out of ten of the cities thought that curfew enforcement was a good use of police officers' time; 88% felt that enforcing a curfew made their city's streets safer; and 83% said curfews help curb gang violence. Of the 154 cities that had had their curfew in effect for ten years or less, officials in 53% of them noted a decrease in juvenile crime (attributed by them to the curfew), 11% saw no change, and 10% saw an increase in juvenile crime (the remaining 26% of cities had no data on the curfew's effects available because of its recent implementation).

However, the effects of curfews on juvenile crime rates are still controversial. In their study entitled "An Analysis of Curfew Enforcement and Juvenile Crime in California" (Western Criminology Review, 1999), Mike Males and Dan Macallair concluded that there was "no support for the proposition that stricter curfew enforcement reduces youth crime or risk of violent fatality…. Curfew enforcement generally has no discernible effect on youth crime." A national study done by David McDowall, Colin Loftin, and Brian Wiersma also found that curfew laws had little effect on juvenile arrests ("The Impact of Youth Curfew Laws on Juvenile Crime Rates," Crime and Delinquency, 2000).