Which is a different matter entirely. I don't think there is any good argument that they shouldn't have to publish the algorithm.
> I'm going to assume that race is not actually used as a weight, I would still like to see the methodology used in determining the validity of the other weights, some of which may act as a proxy for race while not having a significant causal effect on recidivism.
The problem is they're all proxies. Homelessness likely correlates with recidivism, but it isn't the homelessness that causes it, it's the poverty and lack of a support network it implies. Someone with affluent close friends who chooses to live outside because they enjoy communing with nature is in a different situation entirely. But you can measure whether someone has a street address more easily than you can measure their support network, so it gets used as a proxy.
I'm not sure causal effect is the thing you want to hang your hat on anyway, otherwise the existence of racism would imply that race has a causal effect on recidivism and should be used as a factor, which I take it is not the outcome you were after.
It's the other way around. If you only use the other variables but most of the variables that correlate with recidivism also correlate with being black, the algorithm will still predict higher recidivism rates for black people even if it doesn't know anything about skin color.
The more accurate the algorithm is the more it reflects the correlations that exist in the actual outcomes.