Here’s a recent test case on which the Supreme Court decided in favor of a broad, rather than a narrow, reading of Commerce Clause powers: Raich v. Gonzales, in which the Supreme Court ruled (6-3) that the Commerce Clause authorized Congress to regulate the production, distribution, and use of marijuana — even when the marijuana was produced, distributed, and used entirely within the state of California and entirely for non-commercial purposes.

Setting aside the question of what legal or political outcomes you consider to be most desirable, is there any plausible reading of “To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes”, which grants Congress the power to regulate non-commercial transactions for marijuana, carried out between people who live in the same state (and are not members of Indian tribes)? If so, what is that reading and how is it justified?