The International Civil Aviation Organization (ICAO) have established basic medical rules for determining whether a pilot or an air traffic controller is fit to act in that capacity, and they are codified in Annex 1 to the Convention on International Civil Aviation.
However, most countries' aviation authorities have developed their own specific details and clarifications to be used in addition to – frequently more stringently than – the high-level standards prescribed by ICAO.
Some AMEs are designated "senior aviation medical examiner", and may issue first-class certificates, which are required for pilots flying in air carrier operations.
[4] Member states of the European Union Aviation Safety Agency issue their own medical certificates.
An initial Class 1 medical examination must be performed by an Aero-Medical Centre (AeMC), but may be renewed by any suitably authorized AME.