This would depend on the crime and the age of the accused.
Say two brothers conspire to kill the a neighbor and their spouse. One kills the old lady while the other holds them and the switch when killing the old man. One brother is 16 but the other is 18. They are both caught by police while leaving the house covered in blood.
If we do not try the 16 year old as an adult, he will spend the next 2 years in a juvenile facility and leave with a clean record. His brother, on the other hand, even though they were equally to blame for the crime, will spend at least 20 more years if not the rest of his life behind bars. He could even be put to death while his brother walks free with a clean record.
The age at which we consider someone an adult is largely arbitrary. I don't care if we consider someone an adult at 16 or 18 or 21. We could, in fact, have a very interesting debate about which age is most appropriate.
However, whatever age we settle upon (legally we currently choose 18), that signifies the age at which one is able to make legal decisions for him or herself. We do that because we don't believe people below a certain age are responsible enough to make those decisions.
If we don't believe someone is responsible enough to make adult decisions, then it is hypocritical to charge them as adults in criminal trials. Either they're mentally capable or not. So I say if we want to charge younger and younger people as adults, we would need to lower the age of majority at the same time.
We have a jive line justice system for a reason.
Kids are not yet fully mature or developed. Some of the slowest parts to develop are impulse control and empathy, which is why many jive lines commit crimes.
But treating them as adults and putting them in jail for life will actually cause many more problems.
No they shouldn't be.
Children should not have the same responsibilities in the court of law as an adult because they aren't one, kids going through grade and middle school should not be tried as an adult because they don't know things that adults do, they aren't educated enough and forcing them to be trialed by someone with years of law experience, they can be easily berated or scared into lying, you need to approach children differently to adults.
The juveniles will have a harsher punishment than those who go to child courts. The juveniles can have a death sentence and can be behind on education. Imagine a 16 year old sitting in middle school! The effects on the juvenile will be traumatizing and will break the juvenile down.