The decision is not about whether Filburn violated the AAA, it's about if production quotas under the AAA are even constitutional.
Congress has limited powers, and one of those is to regular interstate commerce (The "Commerce Clause"). SCOTUS decided that production quotas counted as regulating interstate commerce, and was therefore constitutional.
Congress has limited powers, and one of those is to regular interstate commerce (The "Commerce Clause"). SCOTUS decided that production quotas counted as regulating interstate commerce, and was therefore constitutional.