This one goes round and round.
Can a JAA license meet the requirements of FAR 61.3 for flying an N-reg around Europe, despite 61.3 using the word issued (but JAA works on validation) ?
I have seen (and have copies of) two replies from the FAA which directly contradict each other.
This is set to remain one of the common sleeping dogs. The other one being whether one needs an IR to fly an N-reg in UK night which (SVFR excepted) is IFR.
More practically, there are two issues here: legality from the licensing POV, and insurance validity.
You are unlikely to get ramp checked - except in France where they reportedly do it to N-reg pilots. Rumour has it that the Frogs have special briefing packs which show them what an FAA license looks like and what wording should be on it, to fly an N-reg on an IFR flight.
But if there was an incident, the insurance will not pay out if the paperwork is deemed to be duff i.e. the flight itself was illegal. I would love to find out why Graham Hill's estate didn't get the payout; it has been claimed his CofA was invalid but why? Had to be some obscure technicality to catch him out.