An unwelcome but necessary step

At O'Hare International Airport and at airports around the country, a full-body scan may soon be a routine preliminary to boarding an airplane. Given the personally invasive nature of the technology, it's hard to get too excited about that prospect.

But at the same time, it seems almost irresponsible not to employ the scanners in some capacity. The only question is what capacity.

As President Obama acknowledged Tuesday, the systems already exist that could have - and should have - identified the threat Umar Farouk Abdulmutallab posed before he allegedly smuggled an explosive device on board a Detroit-bound Northwest Airlines international flight on Christmas Day.

But, as Obama also acknowledged, the Northwest situation also reminds us that "the margin for error is slim, and the consequences of error could be disastrous."

Full-body scanners might not have been necessary to spot Abdulmutallab's threat, but they certainly would have provided an added, even-more-imposing safeguard.

The questions left to address, then, become when do we employ the devices and how do we manage them?

That they ought to be used immediately at least as a so-called secondary service - scanning random passengers and passengers flagged as a security risk - seems to go without saying. And it is not hard to envision them as primary tools, scanning every passenger, in times of high threat or as the threats increase.

But before we reach that level, we need to be sure the system can be operated in a way that protects the privacy and religious sensibilities of passengers.

It's important, for instance, that the images - which essentially portray the nude body of the person being scanned - not be kept beyond the time of the scan, that the scanning be discreet and that the persons doing the scanning be held to high standards of professionalism and decorum. If such standards can be guaranteed, full-body scanning can certainly add a layer of protection against attack.

It can't guarantee security, of course. Nothing can. And, for that matter, it cannot replace the kind of unbending, thorough intelligence and surveillance that Obama admitted was lacking in Abdulmutallab's Christmas Day attack. Indeed, Obama is correct to demand better-coordinated, more intensive operations by the nation's intelligence agencies, and the nation is correct to hold Obama responsible for any weakening of such operations.

But the full-body scanners that, alas, will apparently soon be commonplace at O'Hare can enhance the other defensive tools in the fight against terror. They are not exactly a welcome addition to the airport's security apparatus, but a necessary one in the unfortunate state of our contemporary world.