Smoking marijuana does not have any kashruth concerns 1. Eatables however does have many kashruth and therefor requires a kosher certification.
Some medically prescribed cannabis has a hechser (kosher) symbol on it from the OU.
Regarding the Haskafa or philosophical perspective
3 reasons given from Rabbi Moshe Feinstein why cannabis is prohibited in Judaism:
- unproductive waste of time
- stimulates inappropriate desires
- possibly dangerous
How is it different then alcohol?
Rabbi Mendal Kaplan attempts to explain the distinction on headlines radio podcast. He points out that alcohol has opening up affect socially and spiritually, while cannabis has a closing affect.
While I agree with rabbi Kaplan’s distinction that the high of alcohol is very different I would like to point out the problem of alcohol intoxication is equally bad. Firstly i would like to make the case that according to many Rabbinic codifiers there is no instance of heavy drunking in Torah law. On the contrary the Torah and Chazal are full warnings against intoxication.