They are absolutley issued in accordance with ICAO.
ICAO was set up as a result of the Chicago Convention.
The USA hosted the beginnings of the whole thing and are a fully signed up member of ICAO, if not the dominant member.
With a permanent representative on the board.
Some 80-90% of all aviation activity world wide takes place under the provisions of the FAR's.
The USA is in conformity with All the Annexes of the Chicago convention and as is their right, indeed duty under the convention, the US has notified ICAO of differences between the FAR's and ICAO, Such notified differences do not affect conformity with ICAO.
Almost every state has noted differences with ICAO including the JAA member states.
FAR 61.101 Rereational pilot privilages and limitations.
(g)A recreational pilot certificate issued under this subpart carries the notation, "Holder does not meet ICAO requirements"
This is the only such restriction in the FAR's, related to pilot certification.
'the Sport pilot rule has not been promulgated yet'
All the other pilot certifcates, private, commercial and atp do not contain this restriction.
If for the sake of argument to be in conformity with ICAO the certificates had to have such an endorsment recorded on them, immediatley the IAA would be duty bound to redirect all overflights of US registered aircraft around Irish airspace and cancel all US flights into and out of Ireland. until all US pilot certificates were ammended with the required form of words. Even in this extreme example, if it ever came to pass the IAA would be laughed out of court.
SI 333 of the year 2000
The relevant bit.
(10) For the purposes of this Article, a valid and subsisting licence, other than a JAA licence, issued by any other state which is a member of the International Civil Aviation Organisation in conformity with Annex I (Personnel Licensing) to the Chicago Convention purporting to authorise the holder thereof to act as a flight crew member of an aircraft, not being a licence purporting to authorise that holder to act as a student pilot only, shall be deemed to be a licence validated by the Authority under the provisions of this Order entitling the holder thereof to fly as a member of the flight crew of a private aircraft3 insofar as the holder is permitted to do so by the terms of the licence and by the law of the state by which it was issued:
3 i.e. an aircraft used in the private category as permitted by the certificate of airworthiness issued by its state of registry.
Reading carefully the state of issue is required to be in conformity with ICAO, it says nothing about the licence or certificate.
Again the USA is in conformity with ANNEX 1, regardless of the noted differences.
Furthermore it is quite possible that the IAA is acting ultra vires, that is beyond their powers in respect of this part of the SI by prohibiting FAA PPL's from flying using a Class 3 medical, this is just a technical point because a further paragraph gives them the power to do so.
(ii) if the Authority sees fit to do so, it may at any time prohibit the holder of such a licence from exercising the privileges conferred by this sub-paragraph and, in that event, such licence shall cease to be deemed to be a licence validated by the Authority under the provisions of this Order.
However if any FAA PPL was to fall foul of the 'Authority' for flying with a class 3 medical the outcome in court would be far from certain as far as the authority is concerned.
Currently as it stands the best course of action for any FAA PPL to take is to remain current as far as the FAR's are concerned ie BFR etc and to hold at least an FAA Class 2 medical.
This satisfies the requirements of SI 333 (2000)
insofar as the holder is permitted to do so by the terms of the licence and by the law of the state by which it was issued:
and the requirements of AIC Nr 11/04 paragraph 3.1
If you can also hold a JAR Class 2 medical it will certainly cover your ass in the event of any trouble from the IAA.
Your case would be simple.
You are in full compliance with the provisins of the FAR's and in addition have satisfied the medical requirements of the JAR's.