ix PREFACE It is hard to believe that it’s been over 20 years since the first edition of this guide was published. Our hope for the first edition was that it would serve not only as a resource to occupational health professionals but also as a convenient reference for others involved in the commercial driver medical certification process. The extent to which this manual has been utilized has been beyond our imagination. Although much of the original guidance information had been available for years, it was not easily accessible, nor were many examin- ers aware of its existence or location. While the first edition attempted to collate the information primarily from the Federal Highway Admin- istration (FHWA) conference reports, the next few editions focused on the “official” guidance from FHWA and later the Federal Motor Carrier Safety Administration (FMCSA) but included relevant information from the medical literature. The fifth edition took things even further from our original goal, presenting not only the “official” guidance, but inclusion of the “less official” information from the FMCSA’s Medical Review Board (MRB) and Medical Expert Panels (MEP). The long gap prior to this sixth edition saw major changes in the commercial driver medical certification process—we kept waiting for the dust to settle. The FMCSA Medical Examiner Handbook was taken down for update and, several years later, we are still waiting for its return. Since 2007, FMCSA has heard recommendations from numer- ous MEPs and the MRB, but none of those have been incorporated into “official” guidance. The greatest change was the implementation of the National Registry of Certified Medical Examiners (NRCME) along with a new form (several changes even to that) and a lot of bumps in the road. The NRCME limited the performance of the commercial driver medical examinations (CDME) to those who meet specific criteria, including training and certification. This is a far cry from when many of us started performing these examinations, having little to no guidance and no available training.