Businesses are also allowed to require customers who are unvaccinated to wear a mask, even if there are no mandates. “In effect, there’s a quid pro quo–if they want to come into the business, they must adhere to the business’s requirements to keep everyone there safe–and someone who is not vaccinated will pose fewer risks to the other people if they then instead wear a mask,” Margaret Foster Riley, a health law expert at the University of Virginia School of Law, said.