[Know your rights]

If illegality did not cause a decline in usage, then we can conclude that there wouldn't be an increase in usage if the product became legal

I never asserted that illegality did not cause a decline in usage (although that, and your corollary, are possible). My point is that you have not established that illegality did cause a decline in usage, much less that changing legal status or enforcement caused the entirety of the 60% decline you cite.

[robertpaulsen]

"My point is that you have not established that illegality did cause a decline in usage ..."

Why should I?

My post #168 stated, "Marijuana has been illegal for almost 70 years now with no end in sight. Marijuana use dropped over 60% from its high point in 1979."

Actually, my statement is contrary to your claim. If, as you say, I claimed that illegality caused a decline in usage, then how on Earth can marijuana be illegal for 70 years, and have a high point in 1979?

You're the one who attempted to correlate legal status in post #189.

Just go away