Wickard v. Filburn
Congress passed a law limiting the amount of wheat that farmers were allowed to produce. Filburn grew slightly over twice his quota, but he did not sell any of it and instead used it primarily to feed his livestock. The government fined his for growing too much.
Can Congress regulate goods intended wholly for personal consumption under its authority to regulate interstate commerce?
Congress has the authority to regulate any activity which in the aggregate has a substantial effect on interstate commerce.
While Filburn's goods was merely producing wheat and not using it for interstate commerce, it does not matter how indirect the effect is. This legislation is needed to inflate wheat prices. Allowing Filburn to grow his own wheat instead of forcing him to purchase what he uses on his farm may have only trivial effects, but if everyone started doing this, the effect would be significant.
Yes, Congress can stop people from growing food for themselves to protect interstate commerce.
This case not only does not use Marshall's object test, but further eliminates the subject test as well.