Marijuana ( and many other drugs ) can be detected in hair follicles at least 90 days after last use. Also, despite the many ways to Beat the Test that you may have heard of,it remains very difficult to beat a properly administered drug screen. Most of the masking agents are easily detected in a modern drug screen, which means you get to Pee in The Cup again !!! My source is a Step - Daughter who has worked for a major drug testing lab for 10 years.
In my 25+ years as a Commercial Truck Driver, I have watched an office clerk quit her job ON THE SPOT, when notified of " Winning the Lottery " for a random drug test. That particular trucking company also made a habit of " random drug testing " drivers within a day or 2 of returning from vacations, especially of a week or more in length !!! Another time, a diesel truck mechanic ( with a CDL - A license ) quit at the end of his shift, rather than Pee in the Cup. More recently , another CDL - A driver totally changed personalities after submitting to a random drug screen. He spent the next 3 days working in the warehouse and very nervous, like a long - tailed cat in a room full of rocking chairs!!! After the 3rd day, he was GONE !!!
While I do not like having my personal civil liberties violated, without probable cause or due process, I understand it as a circumstance of working in a safety - sensitive industry. To those who think they can Beat the System, I will remind them that : There's a Reason Why that Stuff is Nick - named DOPE !!!