The Federal Motor Carrier Safety Administration (FMCSA) amends the Federal Motor Carrier Safety Regulations (FMCSRs) to incorporate new performance standards for electronic on-board recorders (EOBRs) installed in commercial motor vehicles (CMVs) manufactured on or after June 4, 2012. On-board hours-of-service (HOS) recording devices meeting FMCSA's current requirements and installed in CMVs manufactured before June 4, 2012 may continue to be used for the remainder of the service life of those CMVs. Motor carriers that have demonstrated serious noncompliance with the HOS rules will be subject to mandatory installation of EOBRs meeting the new performance standards. If FMCSA determines, based on HOS records reviewed during a compliance review, that a motor carrier has a 10 percent or greater violation rate (``threshold rate violation'') for any HOS regulation listed in the new Appendix C to part 385, FMCSA will issue the carrier an EOBR remedial directive. The motor carrier will then be required to install EOBRs in all of its CMVs regardless of their date of manufacture and use the devices for HOS recordkeeping for a period of 2 years, unless the carrier (i) already equipped its vehicles with automatic on-board recording devices (AOBRDs) meeting the Agency's current requirements under 49 CFR 395.15 prior to the finding, and (ii) demonstrates to FMCSA that its drivers understand how to use the devices. The FMCSA also changes the safety fitness standard to take into account a remedial directive when determining fitness. Additionally, to encourage industry-wide use of EOBRs, FMCSA revises its compliance review procedures to permit examination of a random sample of drivers' records of duty status after the initial sampling, and provides partial relief from HOS supporting documents requirements, if certain conditions are satisfied, for motor carriers that voluntarily use compliant EOBRs. Finally, because FMCSA recognizes that the potential safety risks associated with some motor carrier categories, such as passenger carriers, hazardous materials transporters, and new motor carriers seeking authority to conduct interstate operations in the United States, are such that mandatory EOBR use for such operations might be appropriate, the Agency will initiate a new rulemaking to consider expanding the scope of mandatory EOBR use beyond the ``1 x 10'' carriers that would be subject to a remedial directive as a result of today's rule.