Propublica has an "interesting" definition of "fairness". It turns out there is a beautiful mathematical result that shows that the different definitions of "fairness" are inherently incompatible with each other and cannot be satisfied at the same time.

This is the best article that summarizes the controversy on this subject:

https://www.washingtonpost.com/news/monkey-cage/wp/2016/10/1...

Paper by Jon Kleinberg and Sendhil M. and Manish Raghavan on this topic https://arxiv.org/abs/1609.05807