The Court decided that Filburn's wheat growing activities reduced the amount of wheat he would buy for chicken feed on the open market, and because wheat was traded nationally, Filburn's production of more wheat than he was allotted was affecting interstate commerce. Thus, Filburn's production could be regulated by the federal government.
So growing and consuming just about anything locally falls under this interpretation, because otherwise you'd buy it in a market that crosses state lines.
Well, that decision was also conducted under the aegis of a wartime America with a President that actually did have much more expansive Article I powers due to the nation being in a state of war.
I could be hopelessly optimistic and naïve but I simply don't see a similar argument holding in a decision today since there's no National Food Board (or whatever the agency was) to set rationing levels or resource priorities for wartime industrial production.
Except the case preceded the war except in its winding its way through the courts, it's New Deal law, after the "switch in time that saved nine" (https://en.wikipedia.org/wiki/Switch_in_time_that_saved_nine... from later in the Wikipedia article on the case:
"In July 1940, pursuant to the Agricultural Adjustment Act (AAA) of 1938, Filburn's 1941 allotment was established at 11.1 acres (4.5 ha) and a normal yield of 20.1 bushels of wheat per acre. Filburn was given notice of the allotment in July 1940 before the Fall planting of his 1941 crop of wheat, and again in July 1941, before it was harvested. Despite these notices, Filburn planted 23 acres (9.3 ha) and harvested 239 bushels from his 11.9 acres (4.8 ha) of excess area."
If they meant to limit it only to keep the states from taxing each other then that's exactly what would have been in the Constitution. For instance Art. I. Sect. 10 is very clear about how states may impose duties and tariffs on imports/exports, it was very much not left to chance.
Knowing the intent of a given clause is helpful for the courts in determining how to interpret the law or Constitution when the written text of the same is unclear. But when the Constitution or law is perfectly clear then that's what the law is.
In this case the relevant clause is "The Congress shall have the Power to regulate Commerce with foreign Nations, and among the several States."
That's it... unlike Art. I. Sect. 10, there are no specific constraints or restrains embedded there, certainly nothing about taxes (since it would be easy enough to simply declare that states could not tax each other, similar to how Art I. Sect. 10 does it).
