You may be interested to know that the 1975 Alaska Supreme Court ruling which legalized cannabis in that state used more or less your exact reasoning. The court

You may be interested to know that the 1975 Alaska Supreme Court ruling which legalized cannabis in that state used more or less your exact reasoning. The court found that as long as cannabis use was not a public health issue, the State had no right to infringe the privacy of one's home. https://en.wikipedia.org/wiki/Ravin_v._State https://en.wikipedia.org/wiki/Ravin_v._State