From the official response:
“According to scientists at the National Institutes of Health - the world's largest source of drug abuse research - marijuana use is associated with addiction, respiratory disease, and cognitive impairment.”
According to those same studies:
Marijuana Addiction Rate: 9% (Illegal)
Caffeine Addiction Rate: 9% (Legal)
Alcohol Addiction Rate: 15% (Legal)
Tobacco Addiction Rate: 32% (Legal)
As for the claim that marijuana use is associated with respiratory disease and cognitive impairment, tobacco also causes the former, and alcohol also causes the latter.
In your response, please address marijuana’s addictive properties and physical effects in relation to these other legal substances, and justify why marijuana should remain illegal why these others are not.