From the Washington Post's editorial today:
[T]o single out welfare recipients by forcing them to undergo mandatory drug testing as a condition of receiving aid is a way of demonizing them and vilifying public aid itself. ...
It would be one thing if GOP lawmakers wanted to require drug testing to ensure that drug-addicted welfare recipients gained access to treatment. But their intent is to disqualify and punish them by knocking them off the rolls of public assistance.
What the Post is saying: If Republicans want to require drug testing of welfare recipients solely because they don't want people using welfare to buy drugs... that's not cool, bro.