Plaintiffs led by the American Beverage Association and the National Restaurant Association took the city to court over the limited ban, which is due to take effect in March.

The measure, approved by the New York Board of Health last month, restricts soda drink servings to a maximum of 16 ounces (475 milliliters) in fast-food and other restaurants, as well as places of public entertainment like stadiums.

That's more than a normal can, but only half the size of the biggest, bucket-like containers that patrons commonly guzzle from in movie theaters, sports arenas and other outlets.

"This case is not about obesity in New York City or the motives of the Board of Health in adopting the rule being challenged," the plaintiffs' complaint said.

"This case is about the Board of Health, appointed by the mayor, bypassing the proper legislative process for governing the city."

There is nothing to stop people from buying as much soda as they like by refilling smaller containers. Also, the ban does not extend to drinks sold in supermarkets or any dairy or fruit drinks, many of which also contain huge quantities of sugar.

Diet and alcoholic drinks are also exempted.

"The exclusion of all alcoholic beverages from the ban is completely irrational. Beer and soda have nearly the same calories per ounce," said Caroline Starke, a spokeswoman for the group filing the lawsuit.

"The application of the ban to some business establishments but not others is arbitrary and capricious."

According to official statistics, some 6,000 people in New York die each year from obesity-linked problems. One in eight adult New Yorkers has diabetes, which can be aggravated by sugar consumption.