I would be in favor of anti-discrimination measures for relativley large groups for which it can be proven that the basis on which they are discriminated against is unfair or untrue.

Its seems plausible to me that both conditions are to a large extent met for most of the groups that are currently protected in this fashion for a certain value of antidiscrim_policy. However I have severe reservations with the current implementation of antidiscrimination policies.

Overall the exact border where "doing something" seems worth while is hard to quantify for me because I would need to compare it to the anti-discrimination measure proposed to see if it was cost effective. But my instinct tends to tell me that such a small inefficency as to be unfixable by market incentives is going to be hard to fix in a cost effective manner by goverment intervention.