Howard plays his card

How many cards do you have in your wallet? Visa, Access, Switch, perhaps? Marks & Spencer, Badgerline bus miles? Now here comes the Howard Card. Yesterday, the Home Secretary produced a glossy brochure to try to persuade us that his National Identity Card will be worth the fee.

Voluntary and compulsory schemes are the two main varieties on offer. Immediately available could be simple plastic cards. Coming soon should be smart cards carrying a memory chip to store much more information about us.

Principled libertarians oppose ID cards without hesitation, saying they represent an unacceptable extension of state surveillance and a denial of the inalienable human right not to transact with the state and its agents. But such purity of principle is not the way that most people will judge this proposal. The test that needs to be applied is one of balance: are there clear reasons to believe the benefits - tackling crime, making travel and other necessities of life easier - will outweigh the risks - possible infringement of civil liberties? The burden of proof lies with the proposer. On the strength of yesterday's brochure, Mr Howard's case looks like collapsing for lack of evidence.

Take crime first. Only a small proportion of crimes remain unsolved because of difficulties in identifying suspects and Mr Howard offers no evidence that this modest proportion is lower in countries that have identity cards. Peter Lilley, Secretary of State for Social Security, has said that less than 5 per cent of benefits fraud involves impersonation, and therefore cards would not help as much as is sometimes imagined. The more widely the cards are used, the more sophisticated criminals will invest in stealing or forging them.

Would they make life easier? A few things certainly would be more convenient - European travel, for example. But don't imagine that a Howard Card is all you'll need. Tried joining a video club recently? You were probably asked for four different forms of identification, a couple of which should have different photographs. That's because it's harder for someone to steal or forge several identifying papers from the same person than to steal or forge one. Even with a Howard Card, you'd probably still have to show some other ID.

Mr Howard also needs to convince us that personal information on cards will always be accurate, appropriate, known to the person carrying the card and correctable when errors are discovered. Carriers would also need to be told when new information is written into a card, and to receive believable reassurances that the computer system can lock out undesirable snoopers. The technology for this ought to be feasible in theory, but the practical difficulties to be overcome are serious. Also, it is not encouraging that we start from a point where Britain has inadequate data protection laws.

The Green Paper promises blithely that the data on the card will be accurate. But with so many motivations for forgery and so many possibilities of accidental error, it is difficult to see how this promise can be honoured. When the authorities rely upon any single source of identification it can lead to terrible errors: the wrong person invoiced, taken into care or arrested.

With technical advances to safeguard privacy and security, and tougher sanctions on errant card administrators, there might be a much stronger case for the card. In yesterday's brochure, however, Mr Howard just hasn't proved his case. Until he can show us that the card's benefits are worth the risks, we should resist his sales patter.