LAST SUMMER, when he announced the suspension of the much-hated rule forcing passengers to stay seated for the last 30 minutes of airline flights coming into Reagan National Airport, we complimented Homeland Security Secretary Michael Chertoff for his pragmatism. Friday's announcement that the Transportation Security Administration will cease to confiscate scissors and small tools from airplane passengers merits the same praise. TSA boss Edmund S. "Kip" Hawley has pointed out that airport screeners spend far too much of their time and energy confiscating nail scissors from passengers -- 3 million small sharp objects have been confiscated this year alone -- and not enough time looking for improvised bombs, explosives or other more lethal threats. He is right.

There are, perhaps understandably, objections to this rule change, from flight attendants, from the families of Sept. 11 victims and from some members of Congress. Everyone remembers that the hijackings were carried out with ordinary box cutters, which at the time were allowed on planes. But those objecting to the new policy are forgetting that the calculus of risk has changed: Now that all cockpit doors are locked, it is impossible to bring down an airplane with box cutters. It might, theoretically, still be possible to threaten a flight attendant with scissors, but the motivation for a terrorist to do so has to be much lower.

The bottom line is that the investment in the search for scissors, given the risks such instruments pose, no longer makes sense. The cost of the airport screening system, in both budgetary terms and passengers' time, is already disproportionately high; the TSA spends far too much time and money on passengers and not enough on their baggage and cargo. Three years into its existence, it is about time that the Homeland Security Department began to base more decisions on risk analysis rather than sentiment and memories.