A guy who deals dope to kids is a dirtbag that deserves to be put away. A guy who smokes a little ging to unwind is no more a criminal than someone that stops at the local pub to have a few pints. As a matter of fact the guy having a few pints and getting behind the wheel of a car is a far greater danger to society then the guy sitting at home smokin dope and watching Pink Floyd's "The Wall".
So if its really about protecting society, as criminal justice is supposed to be, shouldn't we be more focused on those people that engage in activity that actually is a threat?
There are unfortunately many on this board who would imprison - and perhaps execute - people who commit "morally offense" victimless crimes, if they had their druthers. These same people, had they been born in Saudi Arabia rather than the U.S., would undoubtedly be Jihadist fanatics.
According to moral authoritarians, the criminal justice system is supposed to promote certain popular morals and effect some ersatz social engineering. By promoting zeal, industry, and piousness over sloth and ease, the criminal justice system will lead us to a brighter, more Godly future, and those who resist will receive the benefit of incarceration from their loving Christian brothers.