In the US the big problem is that b/c of the legacy of redlining and segregation, a lot of these algorithms use zip codes which has turned out to just be a proxy for race. So the pre trial release were basically making the decision based on race and age, but b/c no one in the court system actually knew how they worked, no one challenged it.

Cathy O'Neil's got a bunch of good work on it. She had a book a few years ago called Weapons of Math Destruction.