Dairy processors can make claims that their products are free of a synthetic growth hormone, a federal appeals court ruled Thursday in striking down parts of the state's rule on milk labeling.

Key parts of the state's labeling rule violated First Amendment rights to commercial free speech, a three-judge panel of 6th U.S. Circuit Court of Appeals unanimously ruled.

The Organic Trade Association and the International Dairy Foods Association sued the Ohio Department of Agriculture in 2008 over a state rule on how consumers are informed about whether milk is made from cows that were given a synthetic hormone.

The trade groups argued that the rule is too restrictive. It prohibits composition claims such as "antibiotic-free" and "pesticide-free," violating their free speech rights and impeding interstate commerce, the groups argued.

The appeals court reversed a lower court decision on the free speech issue, concluding that the state's ban is "more extensive than necessary to serve the state's interest in preventing consumer deception." The appeals court agreed with a lower court ruling that the rule does not impede interstate commerce.