The litigation privilege immunized a doctor from suit by a bus driver who had consulted her for a medical certification for a commercial driver’s license. The doctor refused to give the certification. Then she wrote independently to the DMV to point out that she had refused to provide the certification and that she felt the plaintiff posed a risk to himself and others due to specified cognitive deficits. The doctor’s letter to the DMV was in the course of a quasi-judicial proceeding and was absolutely privileged. The Confidentiality of Medical Information Act did not prevent application of the absolute privilege under Civ. Code 47(b) since plaintiff arguably consented to the disclosure by hiring the doctor for the purpose of the commercial driver certification and H&S Code 103900 also arguably authorized the disclosure. The privilege even barred a breach of contract claim that plaintiff based on the same underlying facts.