Drug Enforcement Administration
DEA Acting Administrator Chuck Rosenberg says:
Schedule I includes some substances that are exceptionally dangerous and some that are less dangerous (including marijuana, which is less dangerous than some substances in other schedules). That strikes some people as odd, but the criteria for inclusion in Schedule I is not relative danger.
DEA Chief Administrative Law Judge Francis Young says:
Marijuana, in its natural form, is one of the safest therapeutically active substances known to man.