Careful reading of FIFA's statutes shows that, if the FAI position is upheld, it denies the right of players born in Northern Ireland to consider themselves Irish only. FIFA asks that a single nationality, qualifying a player to compete for more than one international team, is held in conjunction with certain territorial or family requirements. A dual national, meanwhile, qualifies, as of right, for teams representing either of his nationalities.
If the FAI wants to take its pick of players born in the north, irrespective of any other criteria, it must rely on an inference that they possess dual nationality and are British citizens, whether they like it or not.
Currently a player who carries an Irish passport can use it as proof of nationality, if he plays for a Northern Ireland team. A few years ago nationalist politicians justly fought a suggestion from FIFA that a footballer could be compelled to produce a British passport in order to confirm eligibility.
Although, to the letter of UK law, everyone from Northern Ireland possesses British citizenship unless it is renounced, the IFA, quite rightly, does not require any of its players to acknowledge British citizenship or carry a UK passport.
The Belfast Agreement has been bandied about to support the Republic's position. In truth, it is the IFA which is working with the grain of the agreement and the FAI and FIFA playing fast and loose with identity rights.
The CAS can't rule for the FAI without accepting that nationalist players, choosing to play for Northern Ireland, are automatically British, whether or not they claim that nationality. That would run counter to the spirit of the Good Friday Agreement.
There are numerous valid objections to the FAI's strategy. Is it ethical for a neighbouring association, on friendly terms with the IFA, to poach young players after they benefit from considerable coaching and investment in Northern Ireland? Is it right to target players from one community background?
The identity issue, however, is the most powerful argument.
Requiring young nationalists to acknowledge British nationality, if they are to represent the Northern Ireland football team, is a fundamentally illiberal notion. If it were the IFA's position, there would be uproar - and rightly so.
Indeed, if the logic were extended further, participation in all Northern Ireland's teams, institutions and the Northern Irish identity itself would depend on an acceptance of Britishness, with Irishness the exclusive preserve of the Republic. That is a recipe for segregation, rather than sharing.