In IDFA v. Boggs, the United States Court of Appeals for the Sixth Circuit ruled in its Sep. 30, 2010 (3-0) decision overturning Ohio's ban on milk labels such as "rBGH free" or "artificial hormone free":

“[T]he 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 [Center for Food Safety] 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.”

Sep. 30, 2010 - IDFA v. Boggs