My comment there:
The science isn’t there?
That has not stopped them from concluding cannabis is harmful, when (in fact) no experimental science concludes any harm from moderate cannabis use (moderate in this case simply means any use without objectively — i.e. conclusively — proven harm).
“Science” against cannabis merely suggests that “heavy use” and abuse may/can cause harm, while those studies (cited by the DEA, and so on) disclaim more research is needed to verify those suggestions.
I put science in unrealism quotes, because three critical factors (necessary for scientific qualification) are left out of such (questionably financed) research. Those factors are intake method differential (e.g. comparing the effects of smoking versus vaporization), precise intake amount (instead of the ridiculously reckless “measurement” of “joints”, or such), and the ever-critical strain differential (there are hundreds, if not thousands, of strains — two of them can even be dramatically different from each other in terms of psychological effect).
What is scientifically proven to be harmful is allowing people with guns and badges to violate their constitutional oath (no rationale upholds the legality of the war on some drugs, factually speaking) to turn weak (actually junk) science into tough-talking affirmations leveraged to enrich themselves (and their leaders) at the terrible expense of public safety (including varyingly ruining the lives of millions of non-violent citizens, experimentally scientifically speaking).