A hodgepodge of activists and advocates has long argued the morbidly obese and the disabled are entitled to a second seat gratis. The case in question was brought by three plaintiffs -- a woman who suffers from rheumatoid arthritis and requires an attendant, wheelchair and crutches; a man who suffered from a rare disease that impaired his mobility (he died before the case was resolved); and the Council of Canadians With Disabilities. They argued airlines were discriminating against them by charging an extra fare because they required additional space to travel comfortably.

The Transportation Agency agreed and adopted its "one person, one fare" policy last January. It requires airlines to provide the morbidly obese with an additional seat if they cannot comfortably fit in one and provides free airfare to an attendant assisting a disabled passenger. Air Canada and WestJet appealed the ruling to the Supreme Court, which rejected the application last week. Representatives for the two airlines say they'll comply with the regulation, but aren't sure how.

"Will we be putting criteria in place to determine whether somebody travels with an attendant out of necessity or out of desire," WestJet spoksman Richard Bartrem told CBC News. "What is morbidly obese? How are we going to make that determination and implement that respectfully, and consistently and fairly?"

It's a valid point. What are the airlines to do? Require a doctor's note? Weigh passengers when they check in? Measure their waistlines to see if they'll fit in one seat? We asked Air Canada if it had come up with a plan to comply with the rule -- which could cost the airline as much as $7.1 million a year -- and were told only that it "intends to comply with the regulation."

For many, the free-seat fracas goes to the question of whether obesity is a disability. A Vancouver Sun columnist argues you can't define a disability without considering the environment in which it exists. The way he sees it, most people would consider a blind man disabled, but if he lives in a land where everyone else is blind, he's just another guy. An editorial in the Denver Post raises the same point. "Airlines should do their best to accommodate all passengers," the Post says. "Yet a majority of obese Americans are making a lifestyle choice. Forcing companies and passengers to make impractical financial adjustments on their behalf is unfair."

Where do you draw the line? Should they get an extra seat at the ballgame? How about a concert? And if the obese can't help being obese, can tall people help being tall? Is making them fold themselves into a coach seat any less discriminatory? Should they be allowed to stretch out in first class without paying extra?

True, a study in the American Journal of Clinical Nutrition suggests that although there is a behavioral element to obesity, genetics also plays a role. Another hypothesizes that a mutation in two specific molecules can cause the body to produce more fat cells. Of course, plenty of studies say otherwise, and if the results of a poll we ran awhile ago are any indication, most people think the obese oughta pony up for the extra seat.

Uncle Sam agrees. The Department of Transportation's official policy (.pdf) states that "if an obese passenger -- whether the passenger is qualified with a disability or not -- occupies more than one seat, airlines may charge that passenger for the number of seats the passenger occupies."

So U.S. airlines are off the hook for now, though a spokeswoman for the Air Transport Association assured us that domestic carriers will comply should the rules change.

Photo by Flickr user Pat+.