The United States Department of Health & Human Services holds patent #6,630,507 dated 2001.
6,630,507 demonstrates Marijuana's benefit for certain medical conditions.
The Department of Health & Human Services is a federal organization yet Marijuana remains illegal under federal law.
Why would the federal government commission a study and obtain a patent for a plant that helps people yet at the same time criminalize it??
Here is the proof: (This opens .gov patent search.)