法律上何歳まで少年として扱われる？
Juvenile delinquency, also known as "juvenile offending", is the act of participating in unlawful behavior as minors (juveniles, i.e. individuals younger than the statutory age of majority). Most legal systems prescribe specific procedures for dealing with juveniles, such as juvenile detention centers and courts, with it being common that juvenile systems are treated as civil cases instead of criminal, or a hybrid thereof to avoid certain requirements required for criminal cases (typically the rights to a public trial or to a jury trial). A juvenile delinquent in the United States is a person who is typically below 18 (17 in Georgia, New York, Michigan, Missouri, North Carolina, New Hampshire, 
Texas, and Wisconsin) years of age and commits an act that otherwise would have been charged as a crime if they were an adult. Depending on the type and severity of the offense committed, it is possible for people under 18 to be charged and treated as adults.
statutory age of majority