At the risk of making an astonishingly bad pun, aviation has a weighty issue on its hands. Samoa Air, the lilliputian airline that services the small Pacific island nation and some near neighbours has lately become the world's first carrier to charge passengers based on their weight.

The announcement closely followed the publication of an influential paper by Norwegian economist Bharat P Bhatta. That paper, which recommended models by which airlines could charge fares based on weight, coupled with Samoa Air's subsequent pricing manoeuvre, has made seismic waves. Some might say disproportionately seismic waves.

Few of the outraged commentators or general travelling public, for instance, will be affected in the short term by the new weight-based fares. Samoa Air operates three propellor driven aircraft in remote locations – two nine passenger Britten Norman Islanders and one three passenger Cessna 172 – hardly an airborne armada. But the question has now been raised: Is this merely a quirky publicity stunt or a sign of things to come?

Certainly Dr Bhatta thinks it should be the latter. Arguing the not illogical line that the more a passenger and their luggage weighs, the more aviation fuel an aircraft burns, he posits that weight-based fares should be introduced by airlines. Taking into account that rising aviation fuel costs are a crucial factor in airline operations, he also adds, with corporate hat firmly on, "that unless subsidized, an airline cannot operate if it cannot cover its costs". Chris Langton, Samoa Air's CEO has taken a similar line. "What makes airplanes work is weight. We are not selling seats, we are selling weight," he said in a CNN interview earlier this month.

One imagines that from a purely economical standpoint, airline management around the globe would be rushing to implement such a financially rational solution. But herein lies the issue for any airline which might attempt such a controversial approach; weight is a hazardous emotional battleground, a minefield that if wrongly traversed could prove fatal.

It's precisely why legions of columnists around the world, who wouldn't normally gives a tinker's cuss over an aviation story, have seized on this one and why countless more anonymous pundits have chimed in to have their say on chat forums. Weight – and particularly overweight people – excites the passions of the average person like few contemporary issues do. And it seems the two default standpoints regarding overweight people are either disgust and condemnation or sympathy. The kinder words are usually extended to those who suffer from a disability or a medical condition that makes losing weight a challenge or impossible.

One such sympathiser is Anne Bain, manager of AccessAbility Travel, an agency specialising in travel for people with a disability. "For people with a disability, this [fare structure] is just another barrier to their ability to travel," she said. "On Australian domestic carriers there are only two wheelchair users allowed on each flight. To then have to be weighed when checking in and to pay more for each kilo just adds insult to injury. Will wheelchairs, plaster casts, crutches or medical supplies be taxed as well? Where will it end?"

But it's the disgusted and condemning who are currently making the most noise. A recent Sydney Morning Herald article focusing on the issue claimed that 85% of respondents to a poll agreed that overweight people should pay more for their airfares. A similar Travel Weekly online editorial that criticised the fare structure also attracted a spate of comments lambasting the overweight. The internet is awash with outraged expositions from people who once had an obese neighbour as a seatmate on a long haul flight.

The prejudices of the masses aside, there are reasons beyond PR why weight-based fares may run into hot water – chiefly issues of legality. And Australians could soon be on the front line of the battleground given Langton told CNN that there are plans to expand the Samoa Air fleet with an Airbus A320-200 that could service Fiji, New Zealand and our own shores.

Should a passenger with a medically related weight problem find themselves paying an exorbitant fare compared to a passenger of standard weight, then legal recourse on the grounds of discrimination might be sought. Former president of Australian Lawyers for Human Rights, Stephen Keim SC, is of the opinion that such a scenario could be legally tested.

"The International Covenant on Civil and Political Rights… provides that the law shall prohibit any discrimination and guarantee to all persons equal and effective protection against discrimination on any ground such as race, colour, sex, language, religion, political or other opinion, national or social origin, property, birth or other status. The social grouping of 'or other status' has allowed human rights law to evolve as different types of injustice are identified. It is certainly capable of application for people who are the subject of discrimination because of obesity," he said.

If interpreted to the furthest degree, this could spell trouble for any airline that proceeded with a weight-based fare structure. As for Samoa Air, Keim said "[The airline's] new policy flies in the face of this obligation to prohibit discrimination. Despite the attempt to disguise the policy as one that treats all people equally by charging them per kilo, the policy essentially and effectively discriminates against large people. In many cases, this will involve people whose large size amounts to a disability and causes the person disadvantage in many aspects of their lives."

But applying international laws against discrimination within individual countries is by no means an easy feat, Keim acknowledges. A legal remedy depends on the extent to which Samoa has written international human rights obligations into domestic law. Australia has also shown a reluctance to convert its equivalent obligations into law, except on a very restricted, line by line basis," he said. All of which means that while a legal challenge exists as a possibility, airlines can potentially take advantage of a loophole between international and domestic law to implement weight-based fare structures.

Other problems with weight-based fares are likely to arise, however. For instance, if these fares were implemented across major carriers, it is likely that there would be a resultant lobby for a wider range of seats within aircraft.

Currently everyone pays the same fare and consequently are given the same sized seat. But a passenger weighing 130kg and paying double that of a 65kg individual might reasonably ask for a seat with the width to accommodate them.

In this Samoa Air are in agreement. "It works both ways. People who pay more deserve more. They've paid their fare and we try to give them what they should have, which is a comfortable seat. We try to make sure they have space around them and that taller people have got more leg room," Langton told CNN.

This might be achievable in a smaller aircraft, where the front seat is more commodious than those at the back, but it's fairly unlikely that larger airlines will be willing to retrofit their cabins with seats of all sizes – an undoubtedly costly enterprise.

Bain suggests that airlines should take a leaf out of US carrier Southwest Airlines' book. According to the airline's charter, customers of size are accommodated with a complimentary second seat if it is deemed that one seat simply isn't enough. But whether other airlines will be so accommodating remains to be seen.

Clearly Samoa Air's renegade take on airfares has ruffled feathers in the aviation industry and beyond. But with the ice now broken and influential proponents such as Dr Bhatta putting economically rational arguments into the public sphere, weight-based fares are likely to remain the elephant in the room for some time yet.