Legal Question in Real Estate Law in California

No, your tenant's hangnail doesn't entitle him to turn your unit into a greenhouse. You could give him a 3-day notice to quit for creating a nuisance (or a 3-day notice to stop cultivating or quit). Make sure you are addressing an actual health or safety issue. Your actions must not discriminate against disabled people.

Marijuana cultivation is still a federal offense, and could subject your property to seizure and forefeiture. Evict the tenant immediately.

The previous answers assume the person asking is the landlord.

The law on this specific issue seems a little cloudy. First, under recent law, cultivation of marijuana is not automatically illegal under California law. Next, however, use of property in violation of drug and alcohol laws constitutes a public nuisance, and such use automatically terminates the lease, and the landlord may evict upon three days' notice. See Code of Civil Procedure section 1161(4). Does the landlord have an obligation to figure out whether the pot cultivation is legal or not? This is an undecided issue. The California Supreme Court is deciding major medical-marijuana cases regularly, including one in early 2010 (People v. Kelly, 47 Cal.4th 1008).

If the lease contained a provision requiring the tenant to "obey all laws," the tenant would be in breach of the lease because of the federal law violation. Not all residential leases would have such a provision. Many commercial leases will, however.

I lean to thinking that if the California appellate courts consider this issue, they will hold that an ordinary residential tenant may not cultivate any amount of marijuana, for any purpose, without the landlord's specific approval. I could be wrong, and I hasten to add that while my research tends to show there is no decision on point, I may have overlooked one.

I can see this getting argued both ways. On one hand, medical marijuana is not illegal under California law, but is illegal under federal law. At the time, President Obama's administration is not enforcing the federal law, but he is not going to be in the White House forever.

Arguably, the tenant has possession of the premises, and has an interest in the property. Were it not illegal on the federal level, the landlord would not have standing to evict or control a tenant's otherwise lawfully prescribed drug use. On the other hand, a court may not choose to enforce the federal violation, and find that the landlord is acting unreasonably.