Now, I have done no research on this, I'm just going by my basic understanding of the Constitution to formulate an opinion, and I could have facts wrong so feel free to correct me here.
It is my understanding that your bodily fluids are your own and without legal action you cannot be forced to give them to someone else. Now, let's say you are a mechanic and you need a job. You go on down to Smith Toyota and they say "we're only high on life here, you must pass a drug test" well, really, they can't force you, you can say 'no thanks' and apply somewhere else. Next you go on down to Bochagaloop Motors and apply for a job, they do not require a drug test and pay just as well as Smith Toyota. Razah! You have beat the system.
Now, let's say you don't have a job or a very low paying or part time job because it is all you could get. Or you are between jobs and need unemployment or food stamps, whatever. The person behind the counter hands you a cup and says you must pass a drug test. Well, at this point you have no other option, you really need the money and if you fail (let's say you had a joint at a friends house the day before) you won't get your Government Assistance. There is no Bochagaloop Motors this time, you can't turn to another Government for a check, but wait! The Constitution is on your side, the 4th Amendment prohibits unreasonable search and seizure therefore the Government cannot force you to hand over your hair/blood/urine in order to receive Government Assistance.
I have even heard before that a place of work cannot fire you for refusal to a drug test. I don't know if that is true but I assume it is.
Anything I missed here? Is there a reason I'm wrong? I just don't understand how both sides can be for this and it hasn't happened other than that pesky Constitution messing everything up.