It’s now been a year and a half since the Transportation Security Administration (TSA) widely implemented what the agency calls “Advanced Imaging technology,” also known as full-body X-rays or, more derogatorily, “porno-scanners.” Despite the outcry in November 2010 over the practice, most polling showed general public support for the scanners ranging from 60 percent to 80 percent. We occasionally get sensational stories about the very young or the elderly receiving invasive searches, as we did recently when the TSA allegedly patted down a “high-security threat” four-year-old after she ran back through security. (Or Jeffrey Goldberg’s mother-in-law.) But the scanners are largely forgotten, and by all accounts most people line up and go through them without much of a fuss.

These scanners were implemented roughly a year after Umar Farouk Abdulmutallab unsuccessfully attempted to blow up an airplane flying from Amsterdam to Detroit. Undoubtedly for at least some Americans, the specter of that attack (and similar ones of their imagining) led to their support for the scanners. The response by the TSA and most supportive Americans seems understandable, even if one disagrees with it.

But if you’re one of that majority of citizens who supports or at least doesn’t mind the TSA, consider this thought experiment. Imagine you’re back on November 19, 2001, the day the TSA was created, before most of these forms of security were put into place. You have a friend in the Department of Homeland Security. She says the TSA is considering mandating the following on January 1: removal of belts and shoes; no liquids besides those carried in clear three-ounce containers; and a choice between an “enhanced patdown” or a full-body X-ray scan, including for children. Would you have supported or accepted these indignities—all of which are now in place—if rather than over ten long years they were implemented in one stroke?

Now, the TSA’s response would be that each of these measures was a response to a specific threat or attack. This is true, but it only shows how manacled we are to a reactive security system. Here’s a list of the dates of terrorist attacks or plots, and responses from the TSA’s own timeline. It includes only those measures I mentioned above, but similar events also provoked bans on lighters and inspections of remote control toys, among other steps.

December 22, 2001: Richard Reid attempts to ignite explosives hidden in his shoe.
December 23, 2001 response: “The [FAA] issues a security directive ordering airlines to add random shoe inspections to the random baggage checks…”

August 10, 2006: British officials stop a plot to blow up an aircraft with liquid explosives.
August 10, 2006 response: “All liquid, gels, and aerosols are banned from carry-ons. TSA institutes mandatory shoe screening to inspect for dangerous items.” (This is later amended to the three-ounce ban.)

December 25, 2009: Umar Faruk Abdulmutallab, called the “Underwear Bomber” for where he hid the explosives, fails to blow up Northwest Flight 253.
November 2010 response: “TSA deploys approximately 500 Advanced Imaging technology units to airports nationwide.” TSA Chief John Pistole states, “We cannot forget that less than one year ago a suicide bomber with explosives in his underwear tried to bring down a plane over Detroit.”

The pattern here isn’t difficult to see (and I’m certainly not the first one to point it out) but it’s worth reiterating: An attack fails because of some combination of bad luck, ineptitude, and good police work; we ban a behavior related to that attack; another attack fails; we ban another behavior.

This is a slippery slope, and we’re most of the way down it. Less than a year ago, a security official actually told Reuters: “[DHS] has identified a potential threat from terrorists who may be considering surgically implanting explosives or explosive components in humans to conduct terrorist attacks.”

Now, just as in the thought experiment, everyone (I hope) tells themselves that mandated cavity and strip searches to detect such explosives would be inappropriate and beyond the pale. But if we catch someone tomorrow at an airport named Umar or Mohammed with a bomb in one of his body cavities, what would be the TSA’s response? And are any of us so sure that, six months after the fact, we wouldn’t all be getting in line and wondering what all the fuss was about?

It’s hard to fathom that we’re still taking our shoes off—millions of Americans every week—because of a single shoe-bombing attempt over a decade ago. While I’d prefer a simple reversion to pre-9/11 security, that’s probably not realistic in the short term. But at the least we could roll back some of these older measures. That the TSA is even considering this step is a rare victory for common sense.