I dont believe that is true, though I wont claim it as fact. I think there are a proportionate amount of studies funded by lobbyists who wish to maintain marijuana's status quo as an illegal class one intoxicant.
right now, it is in their best interest to remain silent.
Ca smokers have done enough to abuse the system, that all anti-marijuana groups have to do is remain silent to gain credibility...
From my own perspective, it is sad that the actions of a few have Ruined it for so many...
This may not be true for the rest of the nation, but CA has been a focal point for other states considering decriminalization