As New York City becomes the first major U.S. city to mandate proof of vaccination for indoor dining and for gym access, many are wondering if it's legal for businesses to ask for your vaccine cards at the door. In fact, it is: businesses are not violating your HIPAA rights if they ask you for this information. UC Hastings College of the Law professor Dorit Reiss explains why businesses are within their rights to tell you, "No vaccine, no service."