One candidate told me that they had actually used someone else's urine for the test and wanted to take the test again with their own sample. I explained to the candidate that they just lied to me and thanks to their poor decision making skills, they were no longer a candidate for a position with our company.
The best defense I have heard from a job candidate for a positive drug test is that they only used the drug for medicinal purposes, which is legal in some states.
One time a woman tested positive for a drug test and her defense was that she had been eating a lot of poppyseed muffins for breakfast. Apparently when they're cut, poppyseeds exude a substance that contains opium alkaloids and in mass can cause a positive drug test. This is really the plot from the 126th episode of NBC's sitcom Seinfeld where Elaine tests positive because of her favorite muffins. But it was too good to not share for this topic!
During one of our routine inspections urinalysis for our employees, one of our top team members returned a false positive after an active ingredient was spotted in his urine. The excuse was simple; he does not drink, however, he thinks that his roommate's coffee might have been the reason why he got a positive test in the first round. As it turned out, this was true, and a later test would prove that the employee does not drink and is thus negative.
The best-failed drug test defense by one of Mobitrix's employees was that it was their kid's 5th birthday, and they couldn't miss it. This employee is always among the best performing in our company but registered a positive drug test after we did a random current employee screening. This commander-directed urinalysis returned did not return any false positive, but one of our trusted employees declared that they had to celebrate because it was a special occasion which, if they failed to celebrate would haunt them for a lifetime. The positive test was for alcohol and no other hard substance. We accepted the excuse as a company because the employee in question had not shown any signs of addiction or registered a positive test before.
Finding out that a potential candidate was positive during a drug test can be nerve-wracking for many employers, but it's always best to wait on an explanation rather than jumping to conclusions. For instance, some candidates may not be want to be outspoken about their mental health problems, even if they're on prescribed medication for certain drugs. By giving them a chance to explain, you may be able to have an open and honest conversation about it.
The best defense I’ve heard was a candidate who was proactive in the initial interview: before the test was even administered, he told us which recreational drugs would show up in the test. By being frank, the applicant appeared forthcoming and honest–which are great traits in an employee. And for some employers, I expect those traits might be even more important than the results of a drug test.