Legal Question in Real Estate Law in California

Re: Roommate moves out

It depends upon so many other things you haven't mentioned that it's hard to give a useful answer. If you have a written lease, the eviction is probably not "legal" unless the continuing validity of the lease is somehow dependent upon the roommate's presence there, possibly having to do with reliance on his credit. Even that sounds like a stretch, since the rent could still be collected from him even if he did not occupy the place.

On the other hand, if this is a month-to-month situation, the landlord can (usually and in most cities) evict for no reason at all (but not for a bad reason such as retaliation) by giving proper notice.

A proper answer would also require knowing whether your city has local eviction control ordinances.

Re: Roommate moves out

If your name is not on the lease, he can evict you. If you are on the lease, as well as the roommate, he cannot evict you unless he does not receive full rent. That means you will need to pay all of the rent if the ex-roomate does not, and try to recover from the ex-roomate. You have a duty to mitigate the damages of the ex-roomate by finding a replacement, even if for a lesser amount. You can go after the ex for the difference.

Once again, there would need to be a breach of the lease agreement in order for there to be an eviction.