Can I evict for drug use, now that marijuana is "legal" in CA?

[Daniel Busby]

I've got a 4-plex that my wife and I are owner occupying in Los Angeles.  For a dozen different reasons we want one of our tenants evicted, but of course tenant laws in LA are pretty strong.  However, we have a potential new development that can be a great way to evict them.  The guy came home last night and dropped something while he was opening his door and didn't notice.  I walked up and found a bag of weed.  I had long suspected that they smoked pot in their unit (can't hide that smell) but didn't have any concrete proof.  Their lease is very clear about illegal drugs use being a non-curable offense and cause for eviction.  But, this is California and recently recreational marijuana passed by voter proposition.  Am I still allowed to evict for their drug use, or is that basically nullified now that pot isn't considered illegal in California.  I'm going to reach out to a lawyer of course, but they won't be open until Monday, and I'm dying to know!