After 80 years of ignoring the data, I do not know how else one would effect change other than employing the same tactics. Empirical data is available, anecdotal data is available, historical harm has accrued for non-violent "offenders". The rarely spoken facets of the hemp plant's superiority to pulp derived paper and cotton fabrics have been ignored for almost a century. Before "reefer madness" was invented, the aforementioned products couldn't compete, hemp was common and priduced superior products. The reasons for demonizing hemp, not marijuana, were economic forces and lobbyists pushing their agendas at any cost.
https://en.wikipedia.org/wiki/Harry_J._Anslinger#The_campaig...