Let's just be glad for what we have, shall we? Even when you hit the bong hard, in our Great State, you can't be thrown in the state clink for it, at least as long as you've got a doctor to back you up. That's the Compassionate Use Act of 1996. Or at least my rough vernacular description of it.
But that doesn't mean you can't be fired for toking up. It's not the Bring Your Bong To Work Act. Nor is it a "Feel Free to Fail the Drug Test" card. Look, it's not that there isn't a reasonable argument to the contrary; after all, if you can't be fired for taking prescription drugs (and you can't), why should you be allowed to be fired for taking your prescription pot? Good argument. But not every good argument is good enough. And the dispositive difference here is that mary jane isn't a prescription drug and is still illegal under federal law. Which doesn't escape Justice Scotland, who affirms a demurrer granted against a dude who was fired when his drug test came back positive.
Sorry, my man. The CUA just keeps you out of lockup. Doesn't keep you in your job.