The ruling said:

The district court held that the composition claims were inherently misleading because ‘they imply a compositional difference between those products that are produced with rb[ST] and those that are not,’ in contravention of the FDA’s finding that there is no measurable compositional difference between the two. This conclusion is belied by the record, however, which shows that, contrary to the district court’s assertion, a compositional difference does exist between milk from untreated cows and conventional milk (“conventional milk,” as used throughout this opinion, refers to milk from cows treated with rbST). As detailed by the amici parties seeking to strike down the Rule, the use of rbST in milk production has been shown to elevate the levels of insulin-like growth factor 1 (IGF-1), a naturally-occurring hormone that in high levels is linked to several types of cancers, among other things. The amici also point to certain studies indicating that rbST use induces an unnatural period of milk production during a cow’s “negative energy phase.” According to these studies, milk produced during this stage is considered to be low quality due to its increased fat content and its decreased level of proteins. The amici further note that milk from treated cows contains higher somatic cell counts, which makes the milk turn sour more quickly and is another indicator of poor milk quality. This evidence precludes us from agreeing with the district court’s conclusion that there is no compositional difference between the two types of milk. In addition, and more salient to the regulation of composition claims like “rbST free,” the failure to discover rbST in conventional milk is not necessarily because the artificial hormone is absent in such milk, but rather because scientists have been unable to perfect a test to detect it. [emphasis added]

Originally published on La Vida Locavore