The following article is meant for educational purposes and does not endorse any illegal activity. Pot remains against the law in most of the USA, permitted only for medical reasons.
The issue of whether pot is kosher for Passover or not allows me an opening. Pot – aside from the debate on its status on Passover as a kitniyot or not — would be prohibited on Passover a rabbinic level, and not biblically. This is very significant. That means that if you use or eat pot for medical reasons YOU CAN USE IT ON PASSOVER. Eating chometz (leavened items) on Passover incurs the penalty of spiritual exile from God and the Jewish people. Being cut off spiritually really sucks. The Rabbinic injunctions regarding kitniyot for Ashkenazim carry weight, but not being cut-off or anything remotely close.
Families that follow Ashkenazi custom may use baby formula on the Holiday, even though most formulas include soy. Soy is kitniyot, and normally prohibited. Since the baby requires this food to stay alive, there is absolutely no question and it is completely permitted to use soy formula, or any other soy product that a sick person or child needs.
In the same vein, here in California, State law permits the use of marijuana for medical reasons. Tens of thousands of Californians carry prescription cards for pot, and can go into licensed pot distribution centers, buy a certain amount of weed, and smoke,
There is another question about smoking versus eating. We are not permitted to benefit at all from chometz on Passover. When I worked in Israel at a glue factory during Habonim Workshop program, on Kibbut Gezer, we made glue for Israeli cigarettes. (The worst ones on the market…) This glue had to be made Kosher for Passover. Chometz which is mixed into another substance but still edible, must be kosher for Passover. So if you are going to use pot under permissible purposes on Passover, make sure not to use rolling papers that might be chometz.