To do so requires looking beyond the legislation and the criminal justice system at ways available to our society to deal with problems such as child poverty and child abuse, which are often an underlying cause of youth crime, and to help young people not to make the kind of choices that may lead them to engage in criminal behaviour.
The criminal justice system is an underlying reason for crimes among the juvenile population
The context states that the criminal justice system "are often an underlying cause of youth crime," so this statement is definitely correct. I think what confused the system is the complex way in which this idea is conveyed in the context. 
( z1 system :mod ( z2 justice :ARG2-of ( z3 criminal ) ) :ARG0-of ( z4 underlie :ARG1 ( z5 crime :ARG0 ( z6 population :mod ( z7 juvenile ) ) ) ) )