More and more employers therefore conduct drug screenings. The most common practice is to test job candidates just before they are formally hired. Many also test current employees when there is reason to believe the person has been using drugs after a work accident in the presence of obvious behavioral symptoms or in the face of chronic lateness or high absenteeism. Some firms routinely administer drug tests on a random basis or periodic basis while others require drug tests when an employee is transferred or promoted to a new position