As noted both on these pages and elsewhere, the TSA has revised its list of items prohibited through airport security.

Corkscrews and nail clippers are back in. So are knitting needles, cigar cutters and blunt scissors. Pool cues and golf clubs are still banned.

Lifting the ban on nail clippers is long overdue, but the contradictory nature of the list of what is allowed and what isn’t just becomes all the more clear.

It seemed odd when metal butter knives were banned, but metal forks were not. Bending back the thynes seemed at least as effective weapon as a dull knife.

Then it seemed even stranger when the ban on metal knives was lifted onboard (an airline could serve them) but passengers couldn’t take them through security! The whole idea of security was to keep items off the PLANE, but the items were allowed on the plane — just not through security.

And as many observers much smarter about these things than I have observed, a security system is most effectively not when it’s foolproof, but when if fails well.

Get something through security? You still have to get through a reinforced cockpit door. Sneak something on board a plane? The pilot isn’t defenseless — the pilot has a gun. Reminding people to do just as the passengers of the hijacked plane did in Pennsylvania — take out the hijackers at all costs, defend themselves — is probably better deterrence than a security system. A terrorist will die AND fail.

Telling folks that security is out of their hands — that (T)aking (S)cissors (A)way solves their problem is precisely the opposite and less secure approach.

Eugene Volokh addresses this issue today over at the Volokh Conspiracy.