I thought it was obvious. What would you test for?
> The potential user's conformance to your ignorance about the effects of cannabis?
A bit obsessed with cannabis are you? The test is before being able to self-prescribe ANY drug.
The same test, and lower the legal age too. Or given current realities, leave the age alone with no test, and with a test a lower age.
But as far as smoking goes you have to make sure to filter the smoke by some method and don't expose others.
> What about sugar?
Yes, sugar can be harmful, but it's hardly in the same class.
It is certainly more addictive: http://www.ncbi.nlm.nih.gov/pubmed/23719144
It would be interesting to have an alcohol license marker on your state-issued photo ID, similar to how most states make a motorcycle license an extra indication on an automobile license. It would have a snowball's chance in hell of passing in the US, but it would be interesting.
2. cannabis smoke doesn't cause cancer because it's not radioactive like tobacco smoke.
Just ask anyone who lives in a medical cannabis state and they will attest that this is how it's done, the same applies for concentrates.