Aside from the obvious infringement of rights and the blanket testing of all welfare recipients profiling them as possible drug users, there's a more practical reason to oppose this. There have already been several states, cities, and counties that have attempted this policy. In each and every once of them less than 5% of the people tested before receiving welfare benefits actually tested positive for any drug. That means the governments who enacted these policies spent more money testing people than they actually saved by denying benefits to the very few they caught on drugs. If you're worried about your tax dollars going to waste, policies that drug test potential welfare recipients should be rejected. If you care about civil rights and liberties and the right to do with your body what you please, these policies should be rejected.