Government Assistance

Its it right to drug test people on Government assistance? Many people think that the ones that get government help, don't try to get jobs or go looking for them. They just sit around so that they can collect money. What about people that are getting disability, is it fair to drug test them, if they are getting the same money as the ones who are unemployed? According to http://www.naturalnews.com/038660_government_assistance_taxpayers_welfare.html many people are on government assistance.
 

http://www.drugpolicy.org/blog/it-makes-no-sense-drug-test-people-who-apply-government-financial-assistance. So is it really worth it to drug test?