Residents of Denver recently voted to legalize possession of marijuana in the amount of 1 oz or less. That’s legalize, mind you, not just decriminalize. 54% of voters were in favour of the ordinance.
The main argument by those in support was that marijuana is a safer alternative to alcohol, as far as recreational drug use goes.
Drug offenders in the US are generally charged under state or federal laws, so this measure may have no real official meaning; but Denver police will presumably not feel too compelled to make any arrests on the matter.