This is an interesting one. It may sound stupid to some people, but in some jurisdictions even if your act is considered legal, the fact that you do it may be a crime. Like if you try to steal something that is already technically yours, in some jurisdictions, this would be a crime. I know it sounds strange, but the logic is if you had the sense of mind to commit the crime and did everything as if it were a crime, you're still guilty.

I support legalization, so that's not an issue for me at all. I'd love to know more details about what the leaf looked like. Was it a leaf, did he have a nug that simply wasn't marijuana. If you're brandishing something resembling marijuana at your school and technically it isn't, you should probably still be punished on some level. A year seems excessive, but that may be a punishment from when they thought it technically marijuana. If that's the school's standard punishment for possession, I don't have too much of a problem with this depending on the facts.