That is an odd usage of the word "customers," but used loosely, that would not be an incorrect term.
yes
Legislative Branch Source: Intro to Criminal Justice-Siegel Legislative Branch Source: Intro to Criminal Justice-Siegel
criminal courts is the largest component in the criminal justice system
Criminal justice is about maintaining both public order and personal freedom. So the benefit of a criminal justice system is a safe place to live and the ability to keep things private. These two ideals sometimes conflict, and criminal justice involves determining whether there is a good enough reason to violate somebody's privacy in hopes of maintaining public order. A benefit of the United States' criminal justice system is that your privacy will not be violated for no reason.
A proponent is someone who supports criminal justice or a criminal justice system.
They're not. A good is something that is available for sale. Police Departments and Courts are not something one can buy. The only time one could use the term "buying the police" is when one is speaking in terms of corruption, but again here it is not literal buying and is more of paying for an illegal service.
because they are bad
How does the Magna Carta affect the criminal justice system
What is John Augustus noted for in the Criminal Justice System?
If you are referring to a particular government system then yes: The United States Criminal Justice System. If you are referring to non-formal system then no: This island we're stranded on needs a criminal justice system.
It's "Criminal" vs. "Civil" justice, that's why. Not criminal/victim :-)
Criminal justice is an ideal which looks toward a system that can properly deal with activity that is morally wrong and in violation of criminal law. Both the criminal law and the definition of "morally wrong" differ between cultures and over time. Criminal justice is about finding the right balance between public safety and personal freedoms.