Pot smoke can cause immediate brain chemistry harm to others. That’s why its public use needs to be severely harnessed. But when creepy, greedy, sociopathic legislators have their way, public safety be damned.I hear what you're saying but we have much better science now and more efficient communication now than existed at the turn of the 20th Century.
Remember there used to be a constitutional amendment banning alcohol. And trust me, pretty much everybody knew tobacco and alcohol abuse was not good for us but pushed that knowledge aside because we wanted to use those products. The dangers inherent in alcohol abuse did not change when the Eighteenth Amendment was repealed by the Twenty First Amendment. It was just that banning alcohol was causing more problems than allowing it. It still remains one of the most tightly controlled substances legal for Americans to buy both at the federal and state levels. And one of the most abused.
Those who want to use cannabis now dismiss all the information and warnings put out by the health authorities and medical community and pretend that its safe or the dangers are small enough not to worry about. They strain at gnats trying to discredit the information and warnings about the potential and prevalent dangers in marijuana use.
Such people believed it should be legal when it was not. Such people point to the injustice of incarceration of those whose only crime was possessing it. Such people call the evidence of danger or those of us reporting it as lies/liars. They believe or even argue there is no downside or danger to anybody when they use it. They would not change their mind if all states again banned the stuff.
For sure there were problems when it was illegal everywhere and it could become as bad as it got when the feds actively tried to enforce prohibition. I think that is what keeps the federal government just ignoring and not trying to attempt to enforce federal laws re marijuana. And even some of our favorite legislators don't want to touch that hot potato when they pick and choose what hills to stand and die on.