Especially with pot, I think it should be legalized. I agree that it shouldn't be done at work, but it really if no different than have a drink. I haven't been able to partake in the pot for the last 10 years, because of random drug test for my job.
I'll share a funny story I had of doing a drug test. The test was at 7 in the morning, so by habit I got out of bed an peed, then went to the test. Couldn't pee, so had to drink 20oz of water and wait for 45 minutes till I thought I had to go. I tried and tried, but the only way I could pee was to poop. Your not supposed to flush the toilet after you pee in the cup, so I went out and handed my sample to the nurse without flushing. I told her what I did and she didn't even bother going in to look, she told me to go in and flush.