Legal Question in Real Estate Law in California

Re: Am I responsible for the lease?

If you are not one of the 'three tenants,' you are not liable to the landlord.

Whether you are liable to one or more of the 'three tenants' probably depends upon whether there was a written, oral or tacitly understood agreement that you would fill the vacancy for the remainder of the lease. This is a question of fact, and how it would come out in small-claims court would depend on the evidence, testimony, witness credibility, and ultimately whether the judge thinks you agreed in one way or another to take the place of the departed roommate.

It might boil down to something as slight as whether you moved in a lot of furniture or only the contents of a brown paper sack, or whether you had a temporary versus a full-time job; in other words, what should the roommates reasonably have expected.

I think you are somewhat more likely to win than lose, simply because a written agreement to fill out the unexpired term would normally have been used if you were obliged to stick it out, but that is certainly not the end of the matter.