Cal. Rev. & Tax. Code § 13683

The Controller may bring suits in the courts of other states to collect estate taxes payable under this part. An official of another state which extends a like comity to this state may sue for the collection of similar taxes in the courts of this state. A certificate by the secretary of state of another state, under the great seal of that state, that an official thereof has authority to collect its estate or other transfer taxes is conclusive evidence of the authority of that official in any suit for the collection of those taxes in any court of this state.