yes, we saw such codes in "The Godfather". Drugs were only to be sold around black people.
But problem is the blacks children teenagers didnt have a strong figure father around to guide them away from drugs, that is there culture weakness, they have to fix
The problem is the culture, it promotes violence, ignorance, and hyper-sexuality while shunning knowledge, education, and love. This is not for all black Americans, but the 'hood is like another world compared to the society most live in.