You are giving infinite leeway to the justice system. A justice system can get so bad that it's better not to have one at all. Even if you place zero value on the human rights of the prisoners, if a justice system can create more crime (for example, by ruining the criminals' families financially, pushing them to break the law in order to get by. Or by ruining the lives of one-time offenders which will make them repeat offenders) than the crime it prevents (by detaining criminals and by deterring would-be criminals), then it's better without it even if it means that crime will have no consequences.

Is the American justice system that bad? Probably not. But if you do place some value on the human rights of the prisoners, and if you take into account the damage done by the prisons and prison accessories industry lobbying? I wouldn't be so sure that its effect is net positive...

"Inherently corrupt" is a property of the system, not of the problem it tries to solve. It does not mean that any conceivable justice system would be corrupt - what it means that any reform that is not deep enough to essentially be equivalent to scrapping it away and rebuilding it anew is bound to fail. The original statement was "the system is inherently corrupt". You changed it to "the vague concept of a Justice System is inherently corrupt". That's a huge difference.

Maggoty's claim, if I understand it correctly, is that the incentives behind the system (profiting from the prisoners) are the problem, and as long as they are not rooted out no reform will help. That's the "inherent" part.