Identity cards, according to their supporters, would make life more difficult for terrorists and illegal immigrants, cut false social welfare benefit claims, reduce crime, and simplify the citizen's dealings with the State, writes Mark Hennessy, Political Correspondent
However, the practical introduction of such a system is fraught with difficulty, as the British government has gradually discovered since then home secretary David Blunkett proposed the idea in 2002.
Though attacked on all sides, the introduction of such a scheme in Britain has taken on renewed impetus since last Thursday's horrific Underground and bus attacks in London, which, so far, are known to have claimed 52 lives.
The creation of a UK identity card makes it inevitable that this State would have to follow.
This the view of Minister for Justice, Equality and Law Reform Michael McDowell - though, politically, he is opposed to them, believing they are an unwarranted interference with privacy.
The rest of the Cabinet agrees.
Indeed some are, privately, even more vigorous in their opposition, though, in reality, Ministers have been drifting in the direction of creating some form of national identification system for several years.
Under an 18-month Department of Social and Family Affairs project, members of the public would be given a "public services card" containing all relevant personal details - name, address, medical card, etc. - that they would need in their dealings with Government departments and State bodies.
The attractions of such a system are obvious.
Members of the public would not have to give basic information again and again, while State bodies would be able to save tens of thousands of man-hours by simply swiping a card to access such information.
In time, the public services cards could contain "biometric" information about citizens, ie, their fingerprints and a record of the iris of the eye - which is regarded as the most accurate way currently of identifying humans, with just a one in 200 billion failure rate.
For instance, biometrics would make it impossible for people to vote fraudulently, which is an issue since there are 300,000 people registered twice or three times on the elector register.
However, a request by a polling station clerk to see a photo ID would probably achieve the same purpose.
But the Government has run into problems with the storage of the most basic information on public services cards - never mind high-tech iris records - since the Data Protection Act guarantees that a citizen's private details cannot be shared around.
This leaves the Government with the difficulty of ensuring, for example, that the Department of Agriculture does not have access to information about a citizen's dealings with a health board, or any other information unnecessary to the Department of Agriculture's contact with the individual.
Last Wednesday, Minister for Social and Family Affairs Séamus Brennan was given permission to spend €2 million and 18 months investigating how the system can be made to work, while overcoming privacy issues and honouring the Data Protection Act.
Such difficulties could make the information technology system required prohibitively expensive.
Though some see the public services card as a nascent national ID card, the two are fundamentally different, since the Data Protection Act does not apply to information held by the State about citizens on matters concerning "public security, defence, State security" and criminal matters.
Regular travellers have become accustomed to such intrusion in recent years, particularly as the United States began to take the fingerprints and photographs of people in Shannon, or Dublin, or at US airports, as it tightened up on immigration controls post 9/11.
Initially, the US warned Ireland and other EU states that they would have to supply passports carrying such biometric details if they wanted their citizens to be able to travel to the US from October 2004, though they have conceded ground since in the face of EU objections.
Irish passports produced in recent years are "machine-readable" and thus the information contained within them can be scanned and read by US immigration staff, though the US still wants passports printed from next year to contain biometric details.
Ireland and the EU still disagree, partly on grounds of cost.
British home secretary Charles Clarke is not finding the going any easier, facing charges that an ID system there would cost approximately £10 billion, fail to stop terrorists and destroy freedoms won over centuries.
Originally the UK ID card was supposed to be compulsory, though the Blair government has conceded ground on this and many other points in the face of stiff opposition. The government will find it difficult to get the measure past the House of Lords - whatever about the Commons - regardless of last Thursday's bombings.
If the ID cards do pass into law in Britain, they will impact on the long-standing Common Travel Area agreement, which has for years allowed people to travel between the Republic and the UK without passport controls, though some form of acceptable photo ID must be carried.
In practice, the travel agreement is, perhaps, of less value than it used to be as airlines and ferries increasingly demand that passengers produce a passport at check-in.
Ryanair, for example, will not carry a passenger without one, regardless of the excuse offered.
However, the introduction of an ID system would have implications for cross-Border travel, though it could be argued that a resident of the Republic without an ID card in Belfast is unlikely to be in a different legal position to a tourist from Spain.