The provision was added at the insistence of Republican conservatives. In the wake of September 11 they became so fearful, they say, of government encroachment on civil liberties that one of their leading organizations–the Eagle Forum–banded together earlier in the year with the American Civil Liberties Union to attack a fledgling effort by state motor-vehicles commissioners to apply minimum-security standards to driver’s licenses. Several of the hijackers used phony driver’s licenses to board their September 11 flights. Yet standardizing the protections to be taken so that licenses can’t be forged would amount to a “backdoor” national identification system that “would be a severe hit to basic privacy rights in America,” the Eagle Forum and ACLU said in a February press release.

In fact, the ACLU and Eagle Forum were on to something. Members of Tom Ridge’s staff at the Office of Homeland Security have been working quietly with the state motor-vehicles officials and the staff of the National Governors Association to help standardize the process by which people prove their identities in order to obtain licenses. That way a driver’s license could become a more reliable nationally accepted identification card for people who drive. Soon after Ridge arrived in Washington, he was told by senior White House aides that the topic was so politically sensitive they were never even to use the term “national identification card,” let alone debate it.

I don’t favor a centralized government identification card either. But not talking about the issue is crazy. Polls show that most Americans are not at all appalled by the idea of having a government card that verifies someone’s identification. What is appalling is that we haven’t debated the issue and come up with a system that protects our liberty while also protecting our security. For soon we surely will have to, and we ought to start the dialogue now.

Here’s why. It is inevitable that terrorists here are going to mimic the suicide bombers who have haunted Israel. And the morning after someone blows up a car, a backpack or himself in a shopping mall, a train, a theater or the lobby of an office building, we’re all going to be standing on the sidewalks for hours waiting to get into all those places, while new, low-wage guards, hired in a panic by owners of these venues, man thousands of checkpoints trying to search us. Commerce and the basic daily movement of people will grind to an infuriating halt.

What I’ve learned in writing about various homeland-security issues over the past year is something that Stephen Flynn, a senior fellow at the Council on Foreign Relations, has been arguing for years: the key is not preventing every attack. That is impossible. Rather, the goal should be to build a security system that is complete enough and credible enough that if an attack succeeds, Americans will know, as Flynn puts it, “that there is a system in place, that may need some fixing, but is there and is likely to prevent the next attack.” The alternative, Flynn adds, is that everything shuts down after an attack while the system gets built–which is what happened after September 11, when the airlines were grounded until short-term precautions could be put in place while a longer-term system could be built. That aviation-security system is, indeed, now mostly built.

Flynn’s abiding obsession is a security system for screening the thousands of cargo containers that arrive at our ports every day. He says one bomb in one crate could shut down the world’s freight commerce at a cost of tens of billions of dollars a day. But Ridge and Customs officials are on their way to building that system, too. They’ve forged agreements to post Customs inspectors in foreign ports, and they’ve added more inspection equipment and radiation detectors and improved computerized screening to find the highest-risk containers.

Where we have made zero progress is in the area that most affects all of us in our daily routines. It’s what the security industry calls “access control,” and it has to do with securing all the spaces where large numbers of people congregate.

Access control can’t be done with the kinds of expensive federal screeners and equipment we’ve deployed, at a cost of $6 billion, at the 1,750 checkpoints at the nation’s airports–because there are hundreds of thousands of such checkpoints. (The New York subway system alone has the same number of entry points as all the airports combined.) We can’t afford it, and it would take so long at each checkpoint that the routine flow of people and commerce would be strangled. Instead, we need an efficient way to prescreen people arriving at those thousands of access points. Which means that some kind of secure, reliable identification card at least has to be debated.

Because most of the problem involves access to places that are not government facilities, the solution cannot come completely from the government. But the Feds have to push the debate and encourage the creation of a system in the private sector.

One possibility–which I find so logical that, after studying the security and legal issues involved during the past year, I am tempted to try launching it myself–would be a system based on some kind of credible but voluntary nationally accepted identification card. The card need not be a government program. It could be issued by private companies licensed by the federal government, which would strictly regulate the card’s standards and use.

Anyone who signs up for the card would be checked against government criminal and watch-list databases that are constantly updated. Those with certain problems in their backgrounds–perhaps they have convictions for felonies, are not legal immigrants here on valid visas or are on watch lists–would not get a card. The private company would not get any specifics about anyone from the government, just a yes or no about whether the person meets the criteria. The card would also have a biometric identifier, such as a thumbprint or an iris scan, to verify the identity of those using it and prevent the ultimate identity theft–by a terrorist.

Those with cards could get on a fast, EZ-Pass-like line, swipe their cards through a machine (that would also check the thumbprint or do an iris scan) and move quickly onto a train or into a terminal or office building. Those who do not want to be screened and pay for cards, or who cannot pass the screening required to get a card, would have to wait on line to be checked more thoroughly.

If that sounds wildly inconvenient or expensive, think about how it might sound the morning after a subway bombing, or the day someone sets off a bomb inside Union Station in Washington, at the Orange Bowl or at the Mall of America.

Because the government would have a connection to the program–by allowing access to its criminal and immigration databases for the background checks, and by regulating the private issuers of the cards–the civil-liberties issues associated with a “national identification system” would not be eliminated. But they would be minimized, arguably to the satisfaction of most who accept that the times demand a new balance between security and freedom from government intrusion.

Fifteen months after September 11, the idea that some people are less of a threat than others–and that they should be able to carry a credible card that verifies that–should not be kept under wraps for fear of offending those who oppose a government ID card. Who knows, they might favor an alternative that enhances security and convenience while staving off a more drastic government-run program that will look awfully appealing amid the panic that is bound to come after the next attack.