Coburn blew it with this question regarding the Commerce Clause. Legislation mandating that each American’s diet include three servings of vegetables per day would not violate the Commerce Clause. The question is whether the Commerce Clause empowers such action by Congress.
It might be reasonable to argue that the Commerce Clause does not authorize legislation regarding diet. However, given the Supreme Court’s rulings in Wickard v Filburn and Gonzalez v Riach, the Commerce Clause seemingly grants unlimited power for Congress to legislate. Certainly, the dietary mandate would affect interstate commerce more than growing crops that are entirely to be used for personal consumption and which cannot legally be sold in interstate commerce. The only remaining limitation that could be applied to a dietary mandate would appear to be the Necessary and Proper Clause. There may be a reasonable argument that dietary legislation is not necessary and proper.
Such legislation would clearly violate the original intent and clear language of the 9th and 10th Amendments. It is likely that Kagan considers these to be dead letters. It would have been much, much better if Coburn had asked whether such absurd legislation violated these amendments.
Coburn would have perhaps been better off asking a question about the government's ability to regulate an individual's diet, absent the reference to the Commerce Clause.
Clearly from Kagan's albeit brief answer, she doesn't seem to have many boundaries with respect to that central question.
It seems to me if the Court is going to so broadly interpret the basket or commerce clauses to allow the government to jail people for not eating veggies, then there really isn't any practical limitations to what they can do. How someone reconciles that with the intent of the Framers, is a mystery.