A high—altitude row between two United Airlines passengers has brought into focus one of the lesser known parts of the US constitution — the 34th amendment, or the so—called right to recline.

The incident occurred somewhere over the Land of Lincoln, when two passengers on a flight from Newark to Denver came close to blows over the use of a “knee defender”, a gadget that prevents the seat in front from reclining. A female flyer discovered that the man in the seat behind had deployed the device and was refusing to remove the clip — even under orders from the flight crew — so she threw water over him. As the row escalated the aircraft diverted to land in Chicago.

Anyone who has flown economy will sympathise with one of the combatants but the incident, which ended without police charges, has highlighted a tension at the heart of American law over the rights of passengers in economy seats.

US law has set the international standard for air travel, with most airlines respecting the flyer’s right to recline at an angle of at least 115 degrees, except during take—off and landing or periods of high turbulence. The same law guarantees a white roll or cheese sandwich with every flight of more than three hours duration. (European flight law is less defined but anyone arrested for misbehaviour on a plane can have the story removed from Google’s search index.)

However, constitutional scholars see the right to recline as an unenumerated right — a view already taken by most low—cost airlines, which regard almost all passenger comforts as unenumerated.

Doubts over the precise legal status mean that the law varies between states. Passengers are currently allowed to recline when flying over Pennsylvania, Illinois and Indiana but are required to return their seats to an upright position over Nebraska, Kansas and Missouri.

Some experts argue the right to recline is restricted to overnight flights and does not apply when the person in the seat behind is more than six feet tall, wears a Brooks Brothers suit or has a really important business meeting at the other end. Most passengers are prepared to accept the case for the right at night but this is complicated by the four time zones in the US. Lawyers disagree over whether the sleeping hours are determined by the current position of the aircraft or the time at the embarkation point.

Many air travellers are angry at the way some airlines are now installing seats that do not recline. The carriers argue that removing reclining seats, especially in cattle class, prevents disputes such as the one seen over Chicago. It may also facilitate their right — as defined under the commerce clause — to cram in an extra three rows of seats across the cabin. But passenger organisations argue that this violates constitutional rights.

In previous decades the courts reliably struck down assaults on the right. The Supreme Court also upheld bans on devices such as the prosthetic arm that passengers wear over their real limb but can leave on the armrest when they dash to the toilet to prevent their neighbour stealing the space.

But changes to the Supreme Court’s composition have raised concerns, however, of a fresh assault on the right to recline. Chief Justice John Roberts evaded questions on the issue during his confirmation hearings. Frequent flyers also note that Justice Anthony Kennedy, regularly seen as a swing vote on the court, is quite tall and so may have less sympathy with the right to recline than his record on issues of personal comfort might otherwise suggest.

The right to recline may simply be the first battle. Airlines are already looking at other economy measures such as windowless planes and rows of so—called “bicycle seats”. Others predict challenges over the right to at least half of the armrest; the right of those in aisle seats to sigh heavily when neighbours ask to squeeze past; and the right to nudge someone who slumps over the boundary line of your seat while sleeping.

Meanwhile, Ryanair, one of the most famously penny—pinching low—cost airlines, is now planning to introduce business class seats. Naturally, this being Ryanair, the seat will be no better than other seats but are reserved at the front or rear of the plane, carry a better baggage allowance and give travellers unrestricted access to Ryanair’s business—class lounge — otherwise known as the terminal.

Financial Times