Hamish McRae: There will be losers and winners in a world of enhanced security

'A generation ago you could leave your mistakes behind you. Now every move we make we leave a track'

Terrorism's legacy is long indeed. Thus one result of the IRA bombings in the City of London is the security cordon, where every car entering the City has its numberplate photographed. We use technology to combat this threat to our security and are prepared to pay a price in a modest restriction of civil liberties.

We have hardly begun to glimpse the corresponding changes in our way of life that result from the attacks of 11 September – how could we? – but there are intriguing signs.

Yesterday Schiphol airport, outside Amsterdam, announced the start of a trial system of border control based on iris recognition and a smart card. The idea is that Europeans can register details of their eyes, which are also carried on the smart card, and then whisk through immigration by looking at a camera and popping their card into a machine instead of having to queue for passports.

It is, of course, an extremely secure system. You can have your passport stolen and it will be converted into a fake. There is an enormous industry on the Continent creating bogus passports – the price, apparently, for a well-faked British passport is about £4,000. You can even have your identity stolen: several of the hijackers of 11 September had stolen other people's identities. But you cannot have your eyes stolen and the iris is an even better means of identification than fingerprints or even the hand-print used by the US immigration authorities.

The Schiphol system is being used not just for travellers but for airport staff who need to have access to restricted areas; indeed the airport reckons to have the iris recognition kit installed at all entry points to these areas by the middle of next year.

Such iris recognition systems are, of course, pre-11 September. But the terrorist attacks will not only increase the need for swift and secure entry systems to sensitive areas; they will also encourage the use of hi-tech solutions to border control. In the case of Schiphol airport's automated border crossing system, the trial requires travellers to volunteer for it, just as people have to volunteer for the US palm-recognition equivalent.

But that is for now. Our views on what is an acceptable security measure and what is not are changing all the time. Six weeks ago it would have been ridiculous that airline passengers would not be allowed to bring nail clippers on board but now, well it is still pretty ridiculous but we accept it. Most of us are relieved by competent and thorough checks before boarding an aircraft. I suspect that were iris recognition to become a common security measure at airports, we would in time accept it being made compulsory – just as we accept security cameras in shopping malls, speed cameras on roads and electronic passes when we go into the office.

However security measures do not need to become compulsory to become pervasive. Convenience is a powerful driver. We don't need to have a credit card but it is hard to do many normal functions, like hiring a car or buying a airline ticket on the internet, without one. A driver's licence has become a de facto ID card. The recent argument about ID cards ignored the reality that while in theory is it not compulsory to carry ID nearly everybody finds it inconvenient not to do so.

So two things are happening. One is that security technology, already advancing rapidly, is given a new push by each outrage. The other is that each new attack ratchets up our willingness to accept the intrusion of such technology as a normal and acceptable part of daily life.

Where will it end? My guess is we face another generation at least of ever tighter control. We will accept that because we will reckon it is better to have our movements tracked than be blown to pieces. But it changes our society.

The traditional objection to additional compulsory security measures is that they curb civil liberties by giving too much authority to the state. We heard those arguments during the debates about ID cards and about the treatment of asylum-seekers, and we will go on hearing them. But without wishing to play down those concerns it seems to me that they are less important than the voluntary security measures that most of us accept. It is these voluntary measures that will change society more radically.

This is because voluntary security measures do two things. First, they create a society of insiders and outsiders: the majority who have credit cards, passports, career references and so on, and the minority who are excluded from the myriad opportunities that a prosperous developed country offers. Second, even among the included majority there will be people who, because of some past mistake or misfortune, find themselves facing an uphill struggle to make something of their lives.

The insider/outsider distinction has already become alarming. In every developed country there are people, often but not always immigrants, who cannot legally get a job and so have to work in the cash economy. They cannot even open a bank account. Millions of people in the UK, Europe and America have to live this way, unable to cross the barrier to legal status and are inevitably exploited.

But even people who have full legal status now lay a trail. A generation ago you could leave your mistakes behind. Now, every time we change a job, open a bank account, even have the washing machine repaired, we leave a track. The mass of information stored electronically about us mounts every day. If you lead a blameless life I suppose this is not a problem. But all of us have at some stage done things we would prefer not to have on our record. And for people who make some serious mistake early on, that mistake can colour their life.

A generation ago people who had made a muck of things could move – emigrate to Australia or whatever. It is harder now. And it will become ever more difficult in the future.

In some ways making people aware that their lives are shaped inexorably by the series of decisions they make is a useful discipline on society. But it is a harsh one.

I first saw iris recognition demonstrated by BT at its labs five years ago and it seemed an extraordinarily powerful technology. If it becomes the new standard by which the developed world protects itself from people who want to destroy its way of life then so be it. But if everyone is to be tracked, then we need to recognise that people need second chances, too.