The 'anytime, anywhere' rule is intended to prevent restrictions on the sale and marketing of 100 per cent fluid milk in schools, and specifically ban these sorts of restrictions in exclusive deals schools have with soft drinks giants.
The law, which forms part of the US Department of Agriculture's (USDA) 2004 Child Nutrition Act, will come in on 21 December, although comments and proposals for amendments will be allowed until 22 May next year.
As it stands, all schools must make the necessary changes to their supply contracts with soft drinks firms by the beginning of the 2006-2007 school year.
"This is a major victory for milk processors," said Victor Zaborsky, senior marketing manager at the International Dairy Foods Association.
"There have been lots of schools around the country that have not allowed milk vending machines in the school because of those soft drinks contracts.
"We are certainly not against competition in schools, all we want is an ability to be there," he told www.DairyReporter.com.
Nearly half of all US schools had an exclusive contract with a beverage company in the 2003-04 school year, according to a report published by the Government Accountability Office this August.
The body found that nearly three quarters of high schools, two thirds of middle schools, and a third of elementary schools had exclusive beverage contracts.
Yet, opinions differ on just how much these deals hamper milk marketing. "Based on discussions with State agencies, we understand that very few if any current vending contracts actually limit the sale or marketing of fluid milk," the USDA said.
It is thought a number of schools began trying to change beverage contracts last year in anticipation of the new law.
"There is much concern about kids' health at the moment and there has been a lot of talk on what restrictions are going to be put on schools," said Zaborsky.
The question is, will pupils really reject coca-cola for the 'white stuff'? After all, American children currently drink three times more soda than milk. And the US National Dairy Council says the country's milk market has been shrinking for decades.
The IDFA has already been working to increase school milk consumption through the Milk Processor Education Programme.
It sponsored research across 300 schools in St Louis and showed that milk consumption rose more than 12 per cent where new flavours, packaging and posters were offered. A quarter of the schools saw consumption jump 34 per cent.