The local International Brotherhood of Electrical Workers, for example, will conduct testing for particular projects at the customer's request. In the instances in which we've had it, we've had very, very low rates of positives - around 2 percent. When testing first showed up, it raised privacy and workers' rights concerns. The American Civil Liberties Union opposes it, saying employers have the right to expect workers not to be high or drunk on the job, but not to require employees to prove their innocence by taking a drug test. Moreover, ACLU said the test results do not measure job performance.
Drug testing can detect marijuana metabolites weeks after it's been consumed.
The ACLU also says regardless of how routine drug tests have become, they are intrusive and prone to error. Harrison and Capasso dispute this. Dr. Kent Holtorf, a physician and medical researcher in Scottsdale, Ariz., is a strong opponent to drug testing. A study by the National Academy of Sciences' Committee on Drug Use in the Workplace concluded the data provides no clear evidence of the harmful effects of drugs, other than alcohol, on safety and job performance. It noted the expense didn't justify the testing.