The Civil Aviation Authority said depending on the situation, passengers who did not comply with an airline's conditions of carriage could be deemed unruly and given a written warning, fined or in exceptional circumstances face prosecution.
But despite this - as Mrs Russell, a former air stewardess, found out when she tried to "lie back and enjoy the flight" - they still exist.
Mrs Russell was travelling with her husband on July 7, on a Korean Airlines flight, when she believed she had her own run-in with the gadget.
"Dinner was served and it was nearing midnight when the lights went out and most passengers settled down to sleep," she said. "Some time later I woke up and twisted and turned uncomfortably in a rather befuddled state."
She suspected the Knee Defender was at play. "The Korean man behind me probably thought that the little old lady in front of him was fair game and didn't know anything about anything," she said.
But having worked for the now defunct Air Wales and New Zealand's former domestic airline, New Zealand National Airways Corporation, otherwise known as NAC, Mrs Russell said she kept up with airline news and had heard of the seat-locking devices.
"Normally when the button doesn't work it still moves a bit - but this was totally jammed," she said.
And while she never actually saw the device, after she got the cabin crew to talk to the man behind her, twice and at considerable length, she had no further problems with her seat and was finally able to get a relaxing night's sleep.
Korean Airlines has not responded to the Herald's requests on its policies around the use of the Knee Defender and the specifics of this incident.
Invented in 2003, the innocuous-looking little clips were created to "defend the space you need when confronted by a faceless, determined seat recliner who doesn't care how long your legs are or anything else that might be back there," said a description on its seller's website.
They work by clipping on to the arms of opened tray tables, preventing the seat in front from reclining.
But rather than simply give users more freedom of space, the devices have fuelled mid-air tensions as the battle between leg-room and the right-to-recline rages.
Late last year, three US flights in nine days were forced to divert as enraged passengers clashed over the limited space between a reclining seat and one's knees - in one case a woman threw a glass of water in the face of a man who had tried to use the device on her seat.
Mrs Russell was shocked people were using the devices.
"When I worked in cabin crew, here and overseas, a long time ago, occasionally passengers gave us trouble, usually when they had been celebrating too much, but I don't remember anyone being deliberately nasty to someone else," she said.
The Knee Defender
• Invented in 2003, by Ira Goldman, to protect travellers' leg room
• They are clips that attach to the arms of a tray table to prevent the seat in front reclining
• They can be adjusted to allow the seat to recline more or less to give the desired
amount of leg room
• They are banned by a number of airlines
Winston Aldworth, Travel editor: Kneed-less recliner decliner
They may take away my leg room, my breathable air, my drinkable coffee and even my edible food. But they will never take away my reclining seat.
The rise of the Knee Defender marks a new low in airborne behaviour - a terminal point in passenger etiquette.
Clip a Knee Defender in place and the person seated in front of you cannot recline their seat. Like AK47s, they're cheap, easy to use and likely to turn a mild disagreement into full-scale warfare.
These things should be banned.
If the seat I have paid for is able to recline then no other passenger has the right to interfere with it. You could ask me not to recline and, being an agreeable chap, I'd generally put my seat back up.
But clipping one of these things in place is the passive-aggressive version of prodding a traveller in the chest. You're asking for trouble.
The weird thing about using a Knee Defender is that it assumes the person reclining their seat is somehow being rude simply for doing what the airline permits them to do with the seat (for which they have paid good money). In fact, it's the Knee Defender wielder who is rudest.
There are rules about reclining your seat, some of which are unwritten: Rule 1: Keep your seat up when meals are being served. Rule 2: Always look sheepish when making eye contact with the person seated behind you. Rule 3: Be reasonable.
If we all stick to Rule 3, we won't need the other rules at all.
