When the Washington Post asked the Federal Aviation Administration for an opinion on Knee Defender, the FAA responded that there is no FAA rule that would ban the use, except during taxiing, takeoff and landing (when seats are required to be upright, so Knee Defender would not be needed anyway).
Note, however, that not every passenger supports Knee Defender use. For every Siciliano who sings its praises, there's another passenger who condemns it.
For instance: travel writer Mitchell Blatt, who covers China, said: "Reclining is the only thing that makes economy seats a little bit more comfortable. Each passenger purchases the right to recline with their ticket, and the person behind them has no grounds to interfere. If they are uncomfortable--as are many passengers--they should recline themselves."
Malaysia-based travel writer Andy McFarlane said similar: "Here in Asia, and indeed in Europe, reclining your seat doesn't seem to be such a potential ignition of air rage just yet, and particularly in Asia, it is a borderline rite of passage for the majority of passengers. I would imagine that someone using the Knee Defender would be quickly told in no uncertain terms to remove it, or else I can foresee that the aggrieved passenger would remove it themselves if possible. Overall, I think it's a novelty more than anything, which does nothing to force airlines to actually reconsider their seating layout and configuration."
Frequent flyer Dirk Aguilar is even blunter: "Knee Defender is preemptive in assuming that the passenger in front will recline but should not be allowed to. It contributes its own little part to social degradation. In my opinion, Knee Defender should be banned as a tampering device."
As for Goldman he said he has never been asked by a flight attendant to remove the $21.95 Knee Defender.
Additionally, in the ten years Knee Defender has been on sale, there are no reported instances of passengers getting thrown off planes for using them.
The point: Knee Defender is pretty stealthy. Probably nobody will notice it, and a passenger who complains about not being able to recline will be told, sorry, your seat is malfunctioning. If there's an empty seat, he will be moved there.
And as for the Knee Defender user, he can relax - knowing his knees (and laptops!) are safe for yet another flight.
--Written by Robert McGarvey for MainStreet