In previous centuries, young offenders had been treated the same as adult offenders. However, this began to change in the 20th century. Young offenders were given different trials through special youth courts, and this continues today.

Young people do not now go to adult prisons. Borstals were introduced in 1902 and young offender institutions replaced them in 1988 to deal with young people.

Since 1909, people below the age of 18 have been treated differently from adults, and the youth justice system has developed separately from the adult criminal justice system. This happened alongside a greater understanding of the development of the brain through neuroscientific and psychological research, and clinical practice in psychiatry and psychology since the late 20th century.

Attitudes towards the age of criminal responsibility have also changed. In 1908, an age of criminal responsibility was introduced for the first time, which was set at seven years of age. But it changed through the years, and then with the 1998 Crime and Disorder Act it was raised to 10 years of age.