The concept of juvenile justice has existed and been debated for centuries.

The idea that a child should be held to a lower standard of responsibility originated in English law, from which the American legal system was derived; the basic idea is that children, who are not fully developed morally and developmentally, should not be held fully accountable for illegal behavior.

While this is an excellent idea in principle, it begs the question courts have grappled with time and again over the years: How old must an individual be before they can be considered fully grown?

In Sir William Blackstone’s “Commentaries on the Laws of England,” the comprehensive expression of English common law, children younger than seven were completely incapable of criminal responsibility and children between seven and 13 were assumed not responsible unless criminal intent could be proven; at 14, all individuals were fully responsible for any actions they committed.

The state of Illinois was the first to adopt this principle by creating separate juvenile courts in 1899. By 1950, every state had its own juvenile courts.

Judge Julian Mack expressed the guiding principles behind these courts when he explained in 1909 that the purpose of his court was to ask of the delinquent before him “What is he, how has he become what he is and what had best be done in his interest and in the interest of the state to save him from a downward career?”

The issue with juvenile courts began with the broad discretion they were initially given. Because they were loosely defined as “quasi-civil” courts, many of the constitutional protections guaranteed to criminal defendants did not apply to the delinquents tried in juvenile courts.

Defense attorneys were not present in early juvenile courts, standard evidentiary procedures were not used and prosecutors were only required to prove guilt with a preponderance of the evidence, rather than beyond a reasonable doubt. This led to a slew of Supreme Court appeals in the 1960s and 1970s that extended those constitutional protections to juvenile courts, most notably In re Gault (1967), which extended Fifth Amendment rights against self incrimination and Sixth Amendment rights to an attorney, notification of charges and confrontation of opposing witnesses to juvenile courts.

Bizarrely enough, the issue with those reforms was that by extending constitutional protections to delinquents, states were emboldened to turn their juvenile courts into mirror images of their criminal counterparts.

Justice Potter Stewart said as much; as the sole dissenter in In re Gault, he stated the purpose of juvenile court was correction, not punishment, so the constitutional safeguards should not apply.

The main reason this is an issue is as Stewart says: there is a fundamental difference is the philosophies of juvenile court and criminal court. In a juvenile court, the focus is on rehabilitation, while the focus is retribution and incapacitation in a criminal court.

Further complicating the matter is increased scientific evidence suggesting 18-year olds — the current line in the sand between childhood and adulthood — should not be considered fully mature in the eyes of the law.

This is well illustrated by the case of David and Sammy Maldonado, two teenagers sentenced to life in prison without parole for felony murder — David Maldonado as the perpetrator, Sammy Maldonado as an accomplice.

Sammy Maldonado was just over 18 when the incident occurred, and David Maldonado was 15 months younger than him. In 2012, the Supreme Court ruled in Miller v. Alabama that mandatory life sentences for juveniles, such as the ones meted out in the Maldonado case, were unconstitutional and ordered the resentencing of all inmates affected.

Because of this, the curious situation arises where David Maldonado, the perpetrator, is now free, while Sammy Maldonado, who was beaten up by the victim, will remain in prison.

Commenting on the case, Laurence Steinberg, psychology professor at Temple University and expert on adolescent brain development, said “It’s quite clear that, at least in the United States, we choose our legal boundaries for reasons other than scientific ones … if you’re looking for a boundary that’s an answer to the question, ‘When do people stop maturing?’, 18 is clearly too young.”

And he is absolutely correct.

Of course, in cases involving heinous criminal intent and full understanding of the crime, juveniles must be treated as adults, but the line in the sand must be moved or erased altogether.

Juvenile courts were designed to provide specialized care for young offenders; we can return to those basic principles by looking at young offenders on a case-by-case basis to see whether incomplete development could mitigate their responsibility.

This must beg the question of what classifies a “young” offender; emerging brain science suggests vital areas of the brain responsible for decision-making do not finish developing until age 25. We can certainly use that as a starting point and refine the system further from there.

Impetuous kids can easily make mistakes, and it is absolutely imperative that our legal system affords them more protection, and for those deserving, a second chance.