Starting Saturday, U.S. airlines are going to start asking you for your birth date and gender when you go to buy tickets. They will hand this information over to the Department of Homeland Security for use in running your name (with these other identifiers) against their watch lists. This is the “Secure Flight” program moving forward.

I copied an image file from the Transportation Security Administration Web site that illustrates the problem TSA is trying to solve. Many different people have the same name. The government wants to do a better job of vetting you against their watch lists.

TSA has done a lot to keep Secure Flight going. It’s been a rolling failure for many years, and at least one serious problem remains: It doesn’t secure air travel. Watch lists don’t include unknown wrongdoers, and eluding identity checks will always be trivially easy (barring a bulletproof, national, cradle-to-grave biometric tracking system).

The privacy problem is simple: Giving better identifying information to the government reduces your privacy by an equivalent amount. Today, that’s not too concerning, and the TSA’s privacy impact analysis for Secure Flight promises they will keep data on most people’s travels for “a short period of time.” But promises can be broken—either in secret, or with the stroke of a pen. And you’ll have no effective recourse when that happens.

According to a Washington Post report, people will not be denied travel if they decline to provide this information. They will just be directed to secondary search. This points to a strategy that a small number of people—people like yourself—can use to have a large influence on this program.

If enough travelers decline to provide information—and threaten not to travel by air—the airlines will be forced into a privacy advocacy role.  To defend their bottom lines, they will lobby against making this data collection mandatory.

As always, protection of your privacy is up to you. Go ahead and indulge your prickly, obstinate side on this one.