Shifting law on masks and physical distancing in workplace The Centers for Disease Control and Prevention (CDC) recently issued welcome updated guidance that fully vaccinated people may safely perform most indoor and outdoor activities without wearing a mask and without physical distancing. The updated guidance is not a legal mandate. CDC’s limited legal authority The CDC has limited legal authority under the Public Health Service Act to issue regulations “necessary to prevent the introduction, transmission, or spread of communicable diseases.” One federal judge recently observed that the law imposes “concrete limits” on CDC’s power. The CDC indisputably cannot license vaccinated individuals to go unmasked contrary to more restrictive state and local public health orders.