It's pretty hard to justify that opinion if you're talking about a profession that has life-or-death consequences. Would you be okay with airline pilots not being tested until they have an "accident"? How about nurses/doctors? The thing about accidents is a lot of them are preventable.

Now, I would be against a law that requires that all jobs require drug testing. That's the thing. You have a choice in the matter. If you want to get a nice job, clean up your shit. If you want to keep smoking pot while you have a job, work at burger king. I think that's perfectly fair.