A specialty doctor (like a Cardiologist or Oncologist) previously went to medical school, had specialty training in a particular field, and then passed an exam to prove knowledge in that field. This resulted in a life time certification for the field the doctor was educated in. The doctor never had to renew that certification.
The problem is that like bread, your doctor can go stale. Doctors that were educated 10,20,20 plus years ago were certified in their specialty, but their skills have not been updated, tested, or improved upon since they graduated.
The American Board of Medical Specialties recognized this problem. They feel that the “measure of physician specialists is not merely that they have been certified, but how well they keep current in their specialty.” Thankfully, they have changed the way doctors get and stay certified.
Read about the new rules