Rand also voted against States Rights on this one (From the JBS The New American Freedom Index)...
On the Amendment S.Amdt. 965 to S. 954 (Agriculture Reform, Food, and Jobs Act of 2013): To permit States to require that any food, beverage, or other edible product offered for sale have a label on indicating that the food, beverage, or other edible product contains a genetically engineered ingredient.
That bill did far more than that. No bill in Congress is ever that simple. There were all kinds of federal reporting requirements that were included in that amendment.