Pre-employment drug testing

This is the most common type of drug test used by businesses, however, it is also the least effective. It is considered to be an "intelligence test" by drug testing professionals. It has the advantage of being inexpensive, since only one test per employee needs to be paid for by the company. However, since most pre-employment drug testing is urine-based and subject to sample adulteration or substitution, the effectiveness of this approach has been questioned by federal legislators. Some organizations have a witness in the room at the time of the testing, but the privacy implications of this, as well as the potential for shy bladder syndrome has limited the use of witnesses outside jails and drug treatment programs. Companies and testing centers that do not use witnesses normally disconnect sources of water from the testing room to discourage dilution, and if there is water in the toilet, it is dyed blue. Other countermeasures, such as making the donor change into a gown, may also be used.

Random drug testing

Random drug testing is the most effective format. In the USA, random drug testing is used by a growing number of corporations, drug rehab centers, prisons, the military, police and fire departments, government agencies, and more recently, schools. Currently, this method is used in 23 of the 50 United States. It may also be used on teens by their parents, or mandated to be performed at school..

The goal of random testing is to discourage drug use among employees, inmates, or students by not telling anyone who or when or where they are to be tested in advance. In addition, random testing is more likely to catch cannabis users, since THC metabolites are fat soluble and have a longer duration in the body than those of many other drugs. It has been suggested that this could indirectly encourage the use of much more dangerous and harmful drugs that are excreted from the body faster.