The Joint Tenancy Deed Trumps the Will
So there we have it ... my client is listed on a deed with his two siblings and his mother as a joint tenants with right of survivorship (see California Civil Code §683 at http://www.leginfo.ca.gov). In such a case, the survivors are said to take title by operation of law.
The joint tenancy deed creates the rights in the property. By including a survivorship right, any other joint tenant alive when another joint tenant dies takes the deceased joint tenant's share. In this case, there were four joint tenants. One died. Each joint tenant went from owning an undivided 25% interest in the real property to an undivided 1/3 interest in the real property.
The way the property is transferred when there has been a death is to record a document entitled "Affidavit Death of Joint Tenant". A certified copy of the death certificate is attached to the Affidavit. Anyone can sign the Affidavit; so long as the joint tenant has really died (ergo the requirement for a certified copy of the death certificate to be recorded with the Affidavit). Upon recording, the other joint tenants own the property exclusively, no probate required by anyone (see California Probate Code §210 at http://www.leginfo.ca.gov)
And that's the point, isn't it? A disinheritance clause in a will controls who will benefit from a probate. Since the joint tenancy with right of survivorship property is not subject to probate (by operation of law, remember?), the disinheritance clause does not apply and my client took his share of the real property. The moral of the story is that if you intend to disinherit someone, you better not own real property jointly with them.