Is it legal to do a drug test on someone without consent?

Question Details: I recently had back surgery and on one of my bills I see $160 for a drug screen. I have been under the same doctors care for at least 15 years and due to my medical issues I have had a full CBC (complete blood count- full blood work up including liver function) every 6 months so any information they needed would be their already. I never signed anything saying they could do a drug test and I donĺt feel that I should have to pay for it. So I would think that if they did the test without my consent and if I needed to give consent then they should have to right the cost off. Important Notice