Can I report a driver operating without a medical certificate? What protection can I expect as a whistleblower and to Whom would I report it?

Yes. Guidelines for reporting a driver operating a CMV without a medical certificate issued by a Medical Examiner and whistleblower protections, i.e., Motor Carrier Employee Whistle Blower Protection, (49 United States Code 31105 and 29 Code of Federal Regulations 1978).