A drug test could cost less than $100 (which is less than what one would typically get from welfare) . when you "catch" someone using then you could save $400+. I understand that not all people who use welfare use drugs but of course there are always a few. some studies show less than 5% use drugs. There are various ways this could be implemented . a month to month bases would be the LEAST effective. A random drug screening maybe once every 6-7 months would be far more appropriate. This keeps those who are not honest on their toes.