So the Feds appealed the Appeals Court decision (which initially ruled in defendends favor on commerce clause grounds), and the Supreme Court remanded it back to the 9th Circuit Court with admonishment respecting stare decisis regarding U.S. vs. Willard (as it applies to the marijuana case).
The 9th Circuit Court rules in favor of Fed Gov on the basis of the commerce clause, instead of Miller vs Texas, 153 U.S. 535 (1894), whereby the 2nd and 4th Ammendments did not in and of themselves limit state action. In other words, the State can act to regulate firearms (not the Fed Gov) acording to the 10th Ammendment and in that the Militia is regulated by the State (not the Fed).
Stewart was caught with machine guns. He said the federal government didn't have jurisdiction over his machine guns since they weren't interstate commerce. Initially, the lower court agreed.
At the conclusion of the Raich marijuana case where the U.S. Supreme Court ruled that even if the marijuana wasn't involved in interstate commerce the federal government still had jurisdiction, the lower court then changed its mind and said that also applies to machine guns.