So how did they test people for drugs?
They gave them a written test, where the test question was basically “do you use illegal drugs or not?” You can see the exact procedure on the sidebar here.
And lo and behold, the overwhelming majority of people answered that they didn’t.
Honestly, welfare shouldn't be removed from those on drugs. Instead, it should be given with stipulation of that the people involved must go to some sort of program to help cure or prevent further drug use. If the person is showing no signs of being willing to take the steps to quit, they get put off of welfare then.