Step 1. Send black teens to courts twice as often as white teens.

Step 2. Pass them through to adult courts twice as often as white teens.

Step 3. Keep them in prisons 60% longer for the same crimes.

Step 4. Use big words like "confounding variables" to pretend that it's complicated.

Sources:

http://www.iamforkids.org/wp-content/uploads/2012/09/Promise...

http://www.allgov.com/news/top-stories/black-americans-given...