The Commercial Driver's License Drug and Alcohol Clearinghouse (Clearinghouse) final rule (81 Fed. Reg. 87686, Dec. 5, 2016), requires State Driver Licensing Agencies (SDLAs) to check the Clearinghouse before issuing, renewing, transferring, or upgrading a Commercial Driver's License (CDL) to determine whether the driver is qualified to operate a commercial motor vehicle. FMCSA proposes to amend the Clearinghouse final rule to require SDLAs to downgrade the CDL of any driver for whom a verified positive controlled substances (drug) test result, an alcohol confirmation test with a concentration of .04 or higher, a refusal to submit to a drug or alcohol test, or an employer's actual knowledge of prohibited drug or alcohol use is reported to the Clearinghouse. Under this NPRM, the CDL downgrade, currently defined in 49 CFR 383.5 as the removal of the CDL privilege from the driver's license, will remain in effect until the driver complies with return to duty requirements set forth in 49 CFR part 40, subpart O. SDLAs will have electronic access to relevant information in the CDL holder's Clearinghouse record through the Commercial Driver's License Information System (CDLIS), which will enable them to initiate the downgrade process and to restore the CDL privilege to the driver's license upon his or her completion of return to duty requirements. This proposal is intended to improve highway safety by establishing a means to enforce the existing requirement that CDL holders who test positive or refuse to test, or engage in other drug and alcohol program violations, must not perform safety-sensitive functions, including driving a commercial motor vehicle in intrastate or interstate commerce. This NPRM does not propose any other changes to the Clearinghouse final rule, nor does it propose any changes to the drug and alcohol testing requirements in part 382 and part 40.