A radical constituency revision is inevitable, writes Stephen Collins, Political Correspondent.
One thing is clear from the preliminary census figures: the current constituency boundaries are out of date and defy the constitutional imperative that the ratio of population to Dáil members should "so far as is practicable be the same throughout the country".
The last thing that most politicians want is a radical revamp of constituencies just before a general election, but they may not have a choice. It all hinges on whether the preliminary census figures, published yesterday, are regarded as a census as referred to in the Constitution and the electoral law.
The argument made by Minister for the Environment Dick Roche in advance of the figures was that the legal definition of a census meant the final figures. As these will not be available until April, there was no reason to think about changing electoral boundaries now.
However, at the formal publication of figures yesterday, the director general of the Central Statistics Office, Donal Garvey, was adamant that in the current computerised age there was little or no difference between the preliminary and the final figures.
He refused to be drawn on the constitutional question, saying: "It is up to the political system to react to these figures."
The political system did react immediately, and the issue was discussed at yesterday's Cabinet meeting. Ministers decided to refer the matter to Attorney General Rory Brady rather than relying on the advice from the Department of the Environment that there was no need to act at this stage.
Nobody doubts that the preliminary figures are now so reliable that the population of each constituency will not change in any meaningful way in the final census report.
More importantly, the figures show such enormous population changes over the past four years that some of the current constituency boundaries are wildly out of line with the accepted variation in the ratio of population to Dáil members as recommended in a landmark High Court case.
The question for the Attorney General is whether the preliminary census figures amount to a census as specified in the 1997 Electoral Act. If they do then a constituency revision, and a radical one at that, will have to be set in train immediately.
Naturally the Government parties, and most of the Opposition, do not relish a boundary change now with their teams in place in most of the 43 constituencies.
The detailed census figures are startling. The most extreme case is the three-seat constituency of Dublin West which now has a population of 92,800 or 30,933 for each Dáil deputy.
This was cited by many people, including Labour TD for the constituency Joan Burton, as a breach of Article 16.2.2 of the Constitution. This states: "The total number of members of Dáil Éireann shall not be fixed at less than one member for each 30,000 of the population, or at more than one member for each 20,000 of the population."
However, legal experts maintain that this provision does not refer to the population of individual constituencies but to the national ratio of deputies to the population. The census found that this ratio now stands at 25,512, which is just over the mid-point of the constitutional provision.
The really important constitutional question which applies to Dublin West and a number of other constituencies is Article 16.2.3. This states: "The ratio between the number of members to be elected at any time for each constituency and the population of each constituency, as ascertained at the last preceding census, shall, so far as is practicable, be the same throughout the country."
This is clearly not the case in 2006, as illustrated by the fact that three-seat Dublin West now has more people than four-seat Cork North Central.
Even more startling is the fact that with just under 120,000 people, the four-seat Dublin North has a bigger population than the five-seat constituencies of Dún Laoghaire, Limerick East, Wexford and Cavan-Monaghan.
These are the most extreme examples from the census figures but there are a range of other constituencies where there are wild fluctuations from the accepted practice of trying to keep the population ratio per TD to an accepted norm across the country.
The issue of fairness was settled in the O'Donovan case of 1961 when the High Court struck down a constituency revision on the basis that the variations were too wide. The court suggested that 5 per cent should be the maximum variation above or below the average, and the Constituency Commission has tried to adhere to that advice.
However, this range has now been breached massively in both directions. Dublin West is 21 per cent over the national average, Dublin North is 17.5 per cent above it, and Meath East 13 per cent over. Others are well below the average, with Dún Laoghaire and Cork North Central having a population-to-deputy ratio of almost 11 per cent under.
A radical constituency revision is, therefore, inevitable. The Electoral Act of 1997 specifies that the number of TDs should not be less than 164 and not more than 168. That will give the commission two extra seats to play around with but it will not be enough to prevent butchering of existing constituencies.
Dublin West and Dublin North will certainly get extra seats, but Dublin North West could be carved up and other Dublin northside constituencies merged. Meath and Kildare should get more seats but neighbouring counties could lose territory.
Cork city will lose another seat, while the two three-seat Kerry constituencies will almost certainly be merged into one five-seater. The same applies to the two three-seaters in Donegal.
The only question is whether all of this will happen before or after the election.