I don't have a problem with drug-testing welfare recipients... so long as every person in the state who also receives taxpayer money is also drug tested. Do it across the board, or don't do it at all. It would be economic discrimination.
That said, the International Commission on The Global War On Drugs has finally issued the report that should have been issued decades ago. The commission admits that we have lost the war, and that the war itself has enabled global crime cartels to multiply and prosper. The commission also suggests most drugs be made legal and regulated, citing that as the most effective way to cause most criminal drug enterprises to immediately implode. These are not novices on the international stage, either. They are well-respected global players who have served in the IMF, world banks, the highest financial and economic posts around the world.
Legalize drugs, regulate them, problem solved. I've said that for over a decade. Now folks high enough to be taken seriously are saying the same thing. Good for them.