Medical Examination Report - the long form
Medical Examiner's Certificate - the "medical card"
Currently, you must carry an original or a copy of the Medical Examiner's Certificate (the medical card) with you in the truck and provide a copy of the certificate to your carrier. The FMCSR does not require an employer (your carrier) to have a copy of the long form, nor does the FMCSR prohibit them from getting it. It's up to you. The carrier can have it if they want it and if you give it to them. The carrier cannot get the report from the physician without a signed release from you authorizing the release of your medical records. They must in any case, however, follow all federal, state and local laws regarding the protection of medical information.
As of January 30, 2014, the Medical Examiner's Certificate will be transmitted to the FMCSA and to your State Driver's License Authority (SDLA) (or you must give a copy of the certificate to the SDLA yourself) and you will not be required to keep a copy of the certificate on you at all times. The exception to that is, you will be given a certificate (medical card) at the time of the examination and it will be valid for 15 days. After the 15 days it will become invalid and the only valid copy is the one on file with the SDLA and the FMSCA. The SDLA nor the FMCSA will receive a copy of the Medical Examination Report (the long form). The long form is to be kept on file at the doctor's office for three years, tho.
After January 30, 2014, the carrier can still request and obtain a copy of the Medical Examiner's Report, though frankly IMNSO they need to provide a reasonable explanation as to why they would need it since the FMCSA nor the SDLA wants or needs it. "We just do," "Because we want it," "It's policy," "Because I said so," and the ever popular, "That's the way we've always done it," are not examples of reasonable explanations.
