A motor carrier must randomly give alcohol tests to 10% of its drivers and must randomly drug test 50% of its drivers. These percentages can be increased or decreased by the Federal Motor Carrier Safety Administration publishing a new percentage rate in the Federal Register. The new percentage requirement would then take place beginning January 1 of the following year.
The tests must be scientifically random, such as using a computer program that randomly chooses based on an employee identification number. The dates for random tests must not be announced and should be spaced randomly throughout the year. If a driver is chosen during the random testing for one period, that driver must still be included in all future random screens. That is, a driver is not “safe” from being chosen for a random screen simply because he was selected during the last screening period.
These regulations are found in Title 49 of the Code of Federal Regulations in Part 382.305.