When are drug tests conducted?

There are a variety of circumstances under which an organization may require a drug test.  Following are the most common or widespread:

  • Pre-Employment:  Pre-employment testing is conducted to prevent hiring individuals who illegally use drugs.  It typically takes place after a conditional offer of employment has been made.  Applicants agree to be tested as a condition of employment and are not hired if they fail to produce a negative test. However, it is possible for employees to prepare for a pre-employment test by stopping their drug use several days before they anticipate being tested.  Therefore, some employers test probationary employees on an unannounced basis.  Some states however, restrict this process.  Furthermore, the Americans with Disabilities Act (ADA) of 1990 prohibits the use of pre-employment testing for alcohol use.
  • Reasonable Suspicion:  Reasonable suspicion testing is similar to, and sometimes referred to, as “probable-cause” or “for-cause” testing and is conducted when supervisors document observable signs and symptoms that lead them to suspect drug use or a drug-free workplace policy violation.  It is extremely important to have clear, consistent definitions of what behavior justifies drug and alcohol testing and any suspicion should be corroborated by another supervisor or manager.  Since this type of testing is at the discretion of management, it requires careful, comprehensive supervisor training.  In addition, it is advised that employees who are suspected of drug use or a policy violation not return to work while awaiting the results of reasonable suspicion testing.
  • Post-Accident:  Since property damage or personal injury may result from accidents, testing following an accident can help determine whether drugs and/or alcohol were a factor.  It is important to establish objective criteria that will trigger a post-accident test and how and by whom they will be determined and documented.  Examples of criteria used by employers include:  fatalities; injuries that require anyone to be removed from the scene for medical care; damage to vehicles or property above a specified monetary amount; and citations issued by the police.  Although the results of a post-accident test determine drug use, a positive test result in and of itself can not prove that drug use caused an accident.  When post-accident testing is conducted, it is a good idea for employers not to allow employees involved in any accident to return to work prior to or following the testing.  Employers also need to have guidelines to specify how soon following an accident testing must occur so results are relevant.  Substances remain in a person’s system for various amounts of time, and it is usually recommended that post-accident testing be done within 12 hours.  Some employers expand the test trigger to incidents even if an accident or injury was averted and hence use term “post-incident.”
  • Random:  Random testing is performed on an unannounced, unpredictable basis on employees whose identifying information (e.g., social security number or employee number) has been placed in a testing pool from which a scientifically arbitrary selection is made.  This selection is usually computer generated to ensure that it is indeed random and that each person of the workforce population has an equal chance of being selected for testing, regardless of whether that person was recently tested or not.  Because this type of testing has no advance notice, it serves as a deterrent.
  • Periodic:  Periodic testing is usually scheduled in advance and uniformly administered.  Some employers use it on an annual basis, especially if physicals are required for the job.  Such tests generally are more accepted by employees than unannounced tests, but employees can prepare them by stopping their drug use several days beforehand.
  • Return-to-Duty: Return-to-duty testing involves a one-time, announced test when an employee who has tested positive has completed the required treatment for substance abuse and is ready to return to the workplace. Some employers also use this type of testing for any employee who has been absent for an extended period of time.
  • Other:  Other types of tests are also used by some employers.  For example, follow-up testing or post-rehabilitation testing is conducted periodically after an employee returns to the workplace upon completing rehabilitation for a drug or alcohol problem.  It is administered on an unannounced, unpredictable basis for a period of time specified in the drug-free workplace policy.  Another type of testing, blanket testing, is similar to random testing in that it is unannounced and not based on individual suspicion; however, everyone at a worksite is tested rather than a randomly selected percentage.  Other types of testing include voluntary, probationary, pre-promotion and return-after-illness testing.