The first official document regarding children in the judicial system is the Declaration on the Rights of the Child of November 20, 1959.
But this Declaration had no real impact on the Member States of the United Nations because it wasn’t a mandatory document (Melnic, 2013). The next most important text that set the landscape of a specific law for minors is the International Convention of the United Nations regarding the Rights of the Child in 1989 ; and especially the articles 37 and 40. The first one states that no minor (understood here as a person under 18 years old) can be sentenced to death or life in prison without the possibility of being released. It also states that any arrest, detention or imprisonment of a minor needs to be a last resort measure and as short as possible. The latter article states that any child who is suspected of, accused of or recognised as having committed an offence shall be treated «in a manner consistent with the promotion of the child’s sense of dignity and worth, which reinforces the child’s respect for the human rights and fundamental freedoms of others and which takes into account the child’s age and the desirability of promoting the child’s reintegration and the child’s assuming a constructive role in society» (ONU, 1989). In this same article, the Convention imposes the Member States to establish a minimum age below which no criminal charges can be brought against the child. It also conveys the message that very young children should be excluded from criminal procedures and submitted to alternative measures instead (Melnic, 2013).
Several other rules regarding this matter were established before and after this Convention, such as the Rules of Beijing on the administration of a justice for minors (ONU, 1985), the Tokyo Rules on non-custodial measures (ONU, 1990) and the Riyad Guidelines on juvenile delinquency (ONU, 1990). The regulations of the Council of Europe regarding the criminal responsibility of minors also played an important role. One recommendation in particular: the Recommendation of the Committee of Ministers on the European Prison Rules. The principle 11.1 of this recommendation stipulates that «children under the age of 18 years should not be detained in a prison for adults, but in an establishment specially designed for the purpose» (Committee of Ministers, 2006). Furthermore, the right to a fair trial (art. 6, ECHR) within reasonnable time and with the presumption of innocence also contributed to shape a justice for minors in European countries (Delsaux, 2016).
Despite the Convention of 1989 compelling the states to set a minimum age for criminal responsibility, the ECHR decided, according to the principles of subsidiarity and proportionality, to let each member state decide what this age should be ; although the Committee on the Rights of the Child strongly argued that this age should at least be set at 12 years old (CRC, 2007, p.10 §33).