When you’re in a hole, stop digging. It’s a well known maxim, but one the government seems completely incapable of applying to ID cards.

Home secretary Jacqui Smith had the spade out again last month [subs March], when she re-launched the much criticised scheme for the umpteenth time.

The BBC loyally reported the government’s line that it had made concessions. Notably, it suggested that cards will not be compulsory and that people will be able to “opt” for biometric passports or driving licences instead.

However, these were identified as ID vehicles in the very first green paper on what the government was then trying to call “entitlement” cards (indeed, it suggested that only people who didn’t travel or drive would need another piece of plastic).

This not only makes sense but has to be the case if you bear in mind that it makes no difference what kind of card you carry as long as it shows that your personal details and biometric information have been entered onto the “national identity register” that will underpin the scheme.

Despite this, Ms Smith did have some new information about how the cards will be rolled out. As previously announced, “non-European Economic Area nationals subject to immigration control” will be the first to have to carry a card.

Ministers have often suggested that this will help to cut illegal immigration, by restricting access to work. The standard response is that illegal immigrants will come to theUK, whether they have an ID card or not, and that employers who don’t ask for a work visa or NI number are unlikely to ask for one.

On the other hand, reputable employers, including NHS trusts, will have another hurdle to jump over – and their HR professionals will effectively find themselves enrolled in a newUKborder police.

Immigration minister Liam Byrne has also suggested that non-EEA foreign nationals will need ID cards to claim benefits. Will this mean benefits such as NHS treatment? If it does, the difficulties will be legion.

Doctors’ organisations have said, repeatedly, that their members do not want to become “state agents”, checking the immigration status and benefit entitlement of people in need of medical help.

Even if they did, it’s far from clear how they would decide who to check - after all, the difference between a non-EEA national subject to immigration control and an EEA orUKcitizen may not be obvious at first glance.

This particular issue might be resolved by forcing everyone to carry ID cards and to present them to access public services. This may well be the government’s intention (and as cards become more and more ubiquitous, it will be harder and harder to leave home without one, “compulsory” or not).

But even then, what would, for example, a doctor in A&E do if they were faced with a non-card carrying person in need of emergency surgery or treatment for a notifiable infectious disease? Let them die? Treat them but call in the cops, deterring others from coming forward?

Meantime, the government has found a whole new category of people to help to get the scheme off the ground: workers in sensitive areas. Initially, that will mean people working in airports and onLondon’s Olympic site. But Ms Smith hinted that it might also mean people who work with children and in healthcare.

This is supposed to reassure public – although airline unions are already saying that ID cards will do nothing to improve airport security and the government has offered no evidence that there is a problem to solve.

As far as the NHS goes, the biggest scandals to hit in recent years have related to individuals who are not only well known but well respected.

At the same time, the government is claiming that its latest move will help staff, because they will be able to get through criminal record and other checks faster. However, it has not explained why the present system couldn’t be better resourced or made more efficient.

Nor has it tackled a host of other issues, such as how the national identity register will actually synch with other databases, or just how many cards people will have to carry to, say, work in a public building and use its IT systems.

The campaign group No2ID points out that the government’s latest re-launch of ID cards meets none of the criteria that its own advisors have set out for it. Most obviously, it still lacks a clear purpose. Yet public services are being pulled in.