For what it's worth, the only thing stopping the federal agents from arresting you off of federal land for a joint is that it's not a priority for them, and the

For what it's worth, the only thing stopping the federal agents from arresting you off of federal land for a joint is that it's not a priority for them, and they aren't going to be giving you a traffic ticket to notice it in passing. If you yelled that you were smoking weed across the street from FBI headquarters but on CA land they totally could go arrest you. Or, to put it a different way. It's not that it's legal in CA. It's that the state won't do anything about it.