Thinking about it some more, taking a legal case may not be useful.
Exceptions are/were made on the basis of where the person is living now.
This priciple came in with the children of farmers and landowners being gifted with free sites.
One argument then was that they they had a right to live on the land and couldn't afford to purchase either sites or housing otherwise.
The fact of living in an area alone or being the offspring of a landowner is not sufficient to justify bending planning laws IMO.
I believe this is a form of undeserved privilege - if its right to develop the land, its right to do so - period.
Other arguments involved the prevention of the erosion of the community fabric by not forcing people to engage in economic migration.
This was seen in some quarters as a reaction to the generational loss of population in rural areas which was leaving "ghost towns".
It was this kind of sentiment as much as any development led greed which led to the roundabout estates we've seen recently.
However the largesse shown to the offspring of landowners or other needy people has been shown to have several implications, not all of them based on extreme need for housing
The proof of this are the vendors seeking to sell the subsequently permitted development and potential purchasers seeking advice on AAM and boards.ie about means to get around the relevant condition.
Thus I see the legal position as totally untenable in principle, not shaky and it needs someone with courage and money to take the case.
I suspect that should any case succeed, establishing the right to build isolated houses in rural locations might not be the end result.
Were that to be the case, the price of land in available locations like Kildare would probably skyrocket out of the OP's reach.
However, the default position is not likely to an automatic grant of permission in such cases, but the imposition of development standards.
These will involve imposing an appropriate density and the restriction of new development to areas where the existing urban fabric can be reinforced.
I do not think that the courts decision will act to undermine the urban fabric of towns by allowing it to be dispersed through development outside of the town limits.
So even if a case is taken, it could result in a conservative approach being taken based on sound planning principles which could lead to teh opposite of the OP's desires.
Yeah, Supermans's probably right - forget I said anything.
ONQ.
[broken link removed]
All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.