Medical marijuana can be banned by the federal government because:

Question 23 options:

A. it involves interstate commerce even if the marijuana is given away for free.

B. it is not a fundamental right to smoke marijuana.

C. the federal government can regulate medical practice by physicians who practice in more than one state or attended medical school in a different state than where they practice medicine.

D. the federal government has already approved Marinol a prescription drug containing THC the active ingredient in marijuana therefore the Food and Drug Administration has supplementary authority to regulate other medical uses of marijuana.

In the Gonzales v. Raich case, the US Supreme Court decided that under the Commerce Clause of the US Constitution, Congress may criminalize the production and use of home-grown cannabis even if for medical purposes.

The Obama administration allowed states to decide as they wish since it did protected kids from taking and it did not cross state lines. Trump administration has a different approach and allowed federal prosecutors to prosecute even in states where it's legal.

According to the FDA website, the FDA did not approve marijuana for any indication, it has approved, however, Epidiolex, that contains a purified drug substance “cannabidiol”.