The stated purpose of such laws is generally to deter disorderly behavior and crime, while others can include to protect youth from victimization and to strengthen parental responsibility, but their effectiveness is subject to debate. Generally, curfews attempt to address vandalism, shootings, and property crimes, which are believed to happen mostly at night, but are less commonly used to address underage drinking, drunk driving and teenage pregnancy. Parents can be fined, charged or ordered to take parenting classes for willingly, or through insufficient control or supervision, permitting the child to violate the curfew. Many local curfew laws were enacted in the 1950s and 1960s to attack the "juvenile delinquent" problem of youth gangs. Most curfew exceptions include: