The worst damage from many nerve injuries is secondary -- it happens in the hours after the initial trauma, as the body's reaction to the damage kills more nerve cells. Researchers are beginning to discover ways to prevent this secondary damage and reduce the eventual harm.

If we are not careful, the deadly attacks on New York and Washington will lead to far worse secondary damage, if the U.S. Congress adopts "preventive measures" that take away the freedom that America stands for.

I'm not talking about searches at airports here. Searches of people or baggage for weapons, as long as they check only for weapons and keep no records about you if you have no weapons, are just an inconvenience; they do not endanger civil liberties. What I am worried about is massive surveillance of all aspects of life: of our phone calls, of our email, and of our physical movements.

These measures are likely to be recommended regardless of whether they would be effective for their stated purpose. An executive of a company developing face recognition software is said to be telling reporters that widespread deployment of face-recognizing computerized cameras would have prevented the attacks. The September 15 New York Times cites a congressman who is advocating this "solution." Given that the human face recognition performed by the check-in agents did not keep the hijackers out, there is no reason to think that computer face recognition would help. But that won't stop the agencies that have always wanted to do more surveillance from pushing this plan now, and many other plans like it. To stop them will require public opposition.

Even more ominously, a proposal to require government back doors in encryption software has already appeared.

Meanwhile, Congress hurried to pass a resolution giving Bush unlimited power to use military force in retaliation for the attacks. Retaliation may be justified, if the perpetrators can be identified and carefully targeted, but Congress has a duty to scrutinize specific measures as they are proposed. Handing the president carte blanche in a moment of anger is exactly the mistake that led the United States into the Vietnam War.

Please let your elected representatives, and your unelected president, know that you don't want your civil liberties to become the terrorists' next victim. Don't wait -- the bills are already being written.

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