Yes, in order to receive tax payers money you should go through a drug test and random drug tests. Unless you are taking medically prescribed medication your welfare status should be revoked if you test positive. Welfare does more harm than good in the first place but some people do need it.
People on welfare should be on welfare to use it, not abuse it. You need help then sure, we will help. If you want the government to condone someone using drugs and support that person then there is a problem. Giving people money who mismanage it is not a good idea. Personally I think economics should be taught at a younger age than as a senior in high school because those misusing their money are likely to drop out anyway. If we can teach people how to use their money right it would be quite beneficial toward society.
Simply put, drugs are illegal and doing something illegal is a crime. I personally don't want tax money going to support criminals or people participating in illegal activities and I'm sure other Americans feel the same way. If anything, those people should get welfare privlages revoked and go through the same thing criminals go through.
If we're going to require drug tests for people receiving welfare, we should also require drug tests for CEOs receiving government subsidies, or teachers getting state and federal funds--heck, we should drug test people before they vote, because they might not be in their right state of mind to choose the proper candidate. We should require all students to take drug tests, because those schools receive tax money.
Yeah, or we could not violate our fourth amendment--no unreasonable searches--and give people who can't afford to feed themselves or their families money to get back on their feet.
In states that have tried this it hasn't been cost effective. The program costs more than any savings.
Instead we should abolish welfare and replace it with public works. Only disabled and elderly people should get money for free. Other people should be given a public works job. Sometimes people can't find a job, then guarantee them one and nobody able-bodied has any excuse not to work!
Pushing aside all the legal and ethical issues, that alone should be more than enough reasons to forget about drug testing. Whether its welfare or in the private sector, the only reason to drug test is to rub their noses in it. Raw power is seductive to be sure, just as surely as its not worth the cost.