This is why we need a test to determine inebriation rather than use.
And, it could be taxed easier than shit. Sure, many will grow their own plants BUT would they do so if getting busted with untaxed pot, simlar to untaxed cigarettes, would remove the liberty of consuming legal pot? Hell, I'd use legalized pot use as positive reinforcement to lower OTHER criminal behaviour. Im betting that many peeps would make a concerted effort to protect their status to legally consume pot IF the authorization to do so was removed in the case of any list of applicable criminal action: including growing a plant.
I suppose that would be tough, considering THC is only fat-soluble, and therefore remains in the system for a while. Alcohol has a, what, 12 hour half-life, so to speak? And it's water-soluble. If there's X-amount of alcohol present in your system, it means you've recently drank and are of course inebriated.
People who smoke a lot of weed, would show high levels as opposed to one who only smokes occassionally, but both at any given time could be completely sober. How would you be able to test for THC usage down to the mere hour?
There's got to be something in the body that raises it's levels significantly when under the immediate influence of marijuana, that could be tested. Dopamine, maybe?
I'm sure there's a way. I doubt this is the real reason why it's illegal, too.
I say it's because of Hemp. Hemp threatens MULTIPLE established industries in this country, including fuel/petroleum/petrochemical, textile/cotton, etc.
Hemp production remains illegal, even though it doesn't contain enough THC to even register on the chart, let alone impair a person. That much is obvious if you've ever tried to smoke leftover stems for a buzz when your out of bud.
The not being able to tax it argument is so beaten, it's not even funny. It's no different than tobacco.