Drug Free Commercial Driver Act of 2013 - Revises regulations that require motor carriers to conduct preemployment, reasonable suspicion, random, and post-accident testing of commercial motor vehicle operators for controlled substances or alcohol.
Allows motor carriers to use hair testing as an acceptable alternative to urinalysis for detecting use of controlled substances by an operator, but only for preemployment testing and random testing (but the latter only if the motor carrier tested the operator at preemployment using the same method).
Requires the Secretary of Transportation (DOT) to develop requirements for laboratories and testing procedures for controlled substances that include mandatory guidelines that establish, among other things, laboratory protocols and cut-off levels for hair testing to detect the use of such substances.
Allows any motor carrier that demonstrates it has consistently carried out a generally applicable hair testing program during the most recent one-year period to apply to the Administrator of the Federal Motor Carrier Safety Administration for exemption from mandatory urinalysis testing.