When an agency adds an exemption the Legislature never authorized, every procedural safeguard in the California APA is put to the test. Clara Vondrich, Public Citizen, uses the California Air Resources Board's insurance exemption to map the outer limits of agency discretion. The session examines what shifting justifications signal about the legitimacy of the underlying rulemaking and whether a last-minute rationale at the final hearing constitutes "new material" triggering the APA's 15-day re-notice requirement. Attendees will gain a practical framework for identifying ultra vires agency action and mounting or defending against a challenge to a final regulation.