HELENA, Mont. -

The Montana Supreme Court has unanimously upheld a rule requiring that milk in Montana be sold or discarded 12 days after pasteurization.

Thursday's decision dismisses an appeal by food distributor Core-Mark International that tried to abolish the "sell-by" rule. Core-Mark had argued that the processor is in the best position to determine the shelf-life of its milk and the 12-day rule discriminates against out-of-state producers who can print "use-by" dates on milk sold in other states.

Core-Mark sued after the state Board of Livestock kept the rule after an administrative appeal process. District Judge Mike Menahan ruled in August 2013 that the livestock board fairly considered the "use-by" dating method and chose to stick with the current rule.

The justices agreed with Menahan in the 5-0 ruling, saying the board properly exercised its rulemaking authority.