Do not say a priori when you mean prima faecie ; in fact you can probably get on without either.

Several countries most advanced from a medical point of view have for the last 20 years done without this drug, " a fact ", says the Board, " which is sufficient to show that there is an a priori case for its total abolition ".

No—it does not. To argue a priori is to argue from assumed axioms and not from experience. The argument here rests on the 20-year experience of several countries, and so is an argument a posteriori.

Prima facie, which is what the writer probably had in mind, means on a first impression, before hearing fully the evidence for and against.