Re: what...
There are specific laws about discrimination on grounds of race/religion/gender/sexual orientation. If the algorithm used any of those factors as inputs then it would be at odds with those laws. Care would be required for anything which might be a proxy for those attributes (such as surname).
It's not that simple. A set of features which individually weakly select for particular characteristics can be combined together to strongly select for race/religion/gender/sexual orientation and thus inadvertently discriminate against these groups. As a trivial and rather obvious example, a retailer might use information on, amongst many other things, makeup and clothing colours purchased. But I bet there are some really subtle things that are not at all obvious because individually they only have a weak effect.
Biting the hand that feeds IT
