Once legal prosecutors understand the development of the human brain, it is clear to see that juveniles should not be tried as adults. The brain finishes maturing in the mid-twenties, and it forms back to front. However, until the front of the brain finishes growing, it is possible to see narcissistic, psychopathic, and callous traits. The last aspect to develop is also the part of the brain that deals with the consequences of actions. Without this in place, people can behave in very impulsive ways. These traits can easily be mistaken for ASPD or psychopathic traits.
Therefore, in a juvenile's brain, the connections between the emotional part of the brain and the decision-making center are still developing - and not always at the same rate. This is why teenagers specifically have such overwhelmingly emotional input and can’t explain later what they were thinking.
Therefore, prior to the maturation of the brain, there is no way of knowing if the juvenile’s emotional reasoning has been fully developed and if they will understand the gravity of their actions.
Society understands that young people can commit horrific actions. Yet, when their brain matures, they understand what they have done, and actually have the reasoning power to see the error of their ways, feel regret, and strike to make amends.
Therefore, it is unfair for juveniles to be tried as adults because, until their brains are fully developed, they are too emotionally immature to be responsible for their criminal actions in the same way as adults.