"I'm a medical doctor" is, in most cases outside of hospitals and clinics, entirely superfluous to the issue at hand. And it's frequently less relevant than you might think inside a hospital or clinic. If you hear someone saying this in any situation outside a medical emergency, I hereby give you permission to deduct 1 point from their debate score.
I say this having also been a medical doctor for 10 years.
> I hereby give you permission to deduct 1 point from their debate score.
I already did, because it looked like a clear invocation of the "appeal to authority" fallacy.
While being an MD can provide insight (depending on the nature of the doctor's practice) in terms of how things impact the practice of medicine, being an expert in a field only really matters when discussing topics that are in that field. Outside of their field, an expert's evaluation carries no more weight than anybody else's.
I say this having also been a medical doctor for 10 years.