A US judge struck down New York City's pioneering ban on big sugary drinks on Monday just hours before it was to take effect.
The court handed a defeat to health campaigners including city mayor Michael Bloomberg and created confusion for restaurants that had already ordered smaller cups and changed their menus.
State Supreme Court Justice Milton Tingling said: "The loopholes in this rule effectively defeat its stated purpose," handing a victory to the beverage industry and other business groups.
The mayor, who has championed the ban as a novel measure to fight obesity, vowed to appeal against the decision.
"We believe the judge is totally in error in how he interpreted the law and we are confident we will win on appeal," Mayor Bloomberg said.
He added: "One of the cases we will make is that people are dying every day.
"This is not a joke. Five thousand people die of obesity every day in America."
As Aslef's annual assembly of delegates begins in Edinburgh tomorrow the general secretary explains the challenges his members - and workers across the country - face