Under FMCSA regulations, what is the consequence of refusing to take a required drug or alcohol test?

Federal regulations treat refusal of a required drug or alcohol test the same as a positive test. A driver who refuses is placed in 'prohibited' status in the FMCSA Clearinghouse and cannot perform safety-sensitive functions until they complete the return-to-duty process: evaluation by a Substance Abuse Professional, completion of any recommended treatment or education, and a successful return-to-duty test. The same applies to attempting to substitute or adulterate a specimen, refusing to provide a specimen, or failing to appear for a test. Privately arranged tests have no standing under federal regulations. The Clearinghouse rule, in effect since 2020, means refusals follow a driver between employers and cannot be hidden by quitting a job.