[alexbecker]

> unintentional side effects, edge cases, and bad incentives.

I'm reminded of Department of Agriculture v. Moreno (http://en.wikipedia.org/wiki/Department_of_Agriculture_v._Mo...). Congress passed a law refusing food stamps to people who lived in shared housing with non-relatives. Of course this was targeting hippies (which is illegitimate in itself--to quote the majority, "a bare congressional desire to harm a politically unpopular group cannot constitute a legitimate governmental interest"), but it naturally hit the very poor especially hard.