Great quote on the subject from Ann Druyan, the widow of Carl Sagan:
“I really believe that the marijuana laws are a terrible injustice. They make no sense scientifically, ethically, legally, or any way. They cost a fortune to enforce and we incarcerate hundreds of thousands of people who have done nothing else, but possess or distribute marijuana. Maybe it’s because I’m a child of the 60’s and marijuana has been such a positive part of my life. I have never seen it as being addictive, having spent weeks, and months, and days of my life (and years) without using marijuana in any form.For me, it’s a kind of a sacrament, something that should be used wisely and in the context of a loving family existence. There’s a place for alcohol too, but there’s no reason why adults shouldn’t be allowed to do something which not only doesn’t add harm to themselves or others, but is a way to enhance the beauty of life, the beauty of eating, of listening to music, of being with friends and family, of being with the one you love.”—Ann Druyan in the video podcast At Home in the Cosmos with Annie Druyan.
THE TEXAS SCRIBBLER 
“something which not only doesn’t add harm to themselves or others”
This is where we should tread cautiously. Overdone, smoking of grass could do lots of harm. I wouldn’t like to encounter too many drivers during their high on the road. Or having my dental surgeon toke one too many before he goes for my jaw… etc.
Otherwise, yes, just like alcohol and cigarettes and other things, government should take their mitts off this case.
There will always be those who do everything to excess, which could be used as an excuse to deny everything to everyone else.
But its just an excuse, and meanwhile, thousands are being imprisoned for something that should not be illegal in the first place. Not to mention the extra taxes we pay to support the enforcers and the prisons they fill.
Dick, for once I totally agree with you.