Fair procedure is a common law doctrine that arises from a line of groundbreaking decisions of the Supreme Court of California dating back to the 1880s.
Certain types of private actors (especially professional associations, unions, hospitals, and insurance companies), due to their overwhelming economic power within certain fields, cannot arbitrarily expel members or employees or deny persons admission for no logical reason; they are obligated to provide a rudimentary form of procedural due process (in the form of notice and a hearing).
For example, the State Compensation Insurance Fund was found liable for $1,131,000 for arbitrarily denying a small medical clinic admission to its preferred provider network.
Because it is possible (though slightly more difficult) to find gainful employment in the motion picture industry without being the holder of an Academy Award, the conduct of the guilds that determine eligibility for the Oscars is not subject to fair procedure.
In contrast, the broader UK doctrine of natural justice applies to both public and private entities.