Other comments have pointed out the risk of redundant encodings /proxy variables. I like to point out that sources of unfairness are possible, even with 100% d

Other comments have pointed out the risk of redundant encodings /proxy variables. I like to point out that sources of unfairness are possible, even with 100% decorrelated non-protective variables. For instance, the data collection and labeling of the data may be biased (You label re-admission to jail with current criminals in jail, and just overfitted to the war on drugs). Or you make a biased decision based on the output of a fair model. Things like not taking into account sample size / uncertainty. Also, breaking the law is at odds with unethical behavior. Unethical behavior is not necessarily breaking the law, but it is still nasty. For instance, from your Facebook likes (not a protected variable) I could deduce all of race, sex, origin, religion. Not against the law, but still discrimination.