[edit] The social argument for banning or restricting substances is also limited when it comes into too great a conflict with the social argument for tolerating individual choice. To even put the freedom to speak privately on the same plane as the freedom to take drugs is to abandon reason itself, not to mention hundreds of years of hard-won liberties and enlightenment. Anti-drug regimes are merely authoritarian. Anti-privacy regimes are totalitarian. There is a world of difference between policing action and policing thought.
In an attempt to make "safe spaces" for all the state is becoming surrogate parents.
It's authoritarian and patronizing.
We don't have a law like that in place for alcohol, but we do for any number of other substances.
This is a bit of a sidebar, but what consequences? DUI, sure. But in Germany, where consumption (but nothing else, including possession; IANAL, not sure if someone holding a joint to your face to drag on counts as possession) of weed is legal I know of no direct consequences you’d face for having consumed marijuana.
Interestingly, the legal structure around these substances apparently avoids banning consumption, limiting itself to banning the obtaining or possession of the substance. But it's worth noting that consumption itself is also prohibited, just without a firm textual basis. For example, if you give birth in a hospital, you will be tested for the presence of illegal drugs in your bloodstream (your consent is not required for this), and if you test positive, your child will be automatically confiscated.
Controlled substances are controlled through a legal framework although admittedly, some of the precursors to drugs are also banned which could count as a technological block on making them.
I have never heard of a confiscated child due to the parent having cannabis in their bloodstream - have you any source?