I'm not saying there isn't systematic racism in the US. I'm not saying that policies don't unfairly target minorities in the US. But you are saying that what is going on now is equal to slavery. And backing that up with prison statistics. You're saying that the 5.3 million people denied the right to vote (source) is equal to four million people (at the a peak of 1860) being forced to work with no pay, ripped from their families, raped, tortured, treated like cattle, and murdered arbitrarily? You're sure about that? The systems don't appear much different...
So to be clear your making the assertion that current marijuana laws have equal effects to slavery. Gotcha. Your perspective of trying to equate these two things diminishes the terrible things the US did 130 (and more) years ago. Blech.
I really don't think it does, and I'm referring more to drug laws in general than strictly marijuana. And we're getting into another territory that I have some experience with. It's much easier to see the evilness of a system that doesn't hide and does what everyone can agree are completely horrible things. It's not always easy to see the insidious horrible things that are done in private and not everyone can agree are awful, those are worse. I'll give you an example. My wife grew up in a family that was poor and both physically and sexually abusive. We can all agree that's awful. I grew up in a family that was rich, educated, verbally abusive, manipulative and inappropriate in so many ways that I can't even uncover them yet. Who does my wife, who has a PhD in clinical psychology think is worse? My family, and I tend to agree with her. That's sort of the difference between slavery and the prison system. It's easy to see how evil slavery was, it's not always so easy to see how evil labeling someone a felon is.
Now, to answer your points. So prisoners aren't forced to work for no, or marginal pay (I believe federal prisoners earn $.14 an hour)? Children aren't ripped from their mothers who are forced into incarceration (often for a peripheral participation in the drug trade, like allowing their abusive boyfriend to deal out of their apartment)? There isn't rape in prison? That solitary confinement isn't an inhumane method of torture? And that the state doesn't participate in carrying out the death penalty? All for what? To make sure suburban kids aren't shooting heroin? Well, I have a cousin who's been clean for 3 years and a dead uncle. The drug war and prison didn't really do much to stop their desire to use drugs, or a source from which they could obtain them.
The difference of course is that we see slaves as helpless pawns and criminals as miscriants that made bad choices and need to be punished. Once you throw the fundamental attribution error into the equation though, you realize that people born into poverty in a certain neighborhood are often born into a system that determines their fate without much individual control. Much like slavery.