The English “common law,” on which much of our jurisprudence is based, shows the way. A venerable common law doctrine is the implied contract associated with being “open for business.” If I advertise prices, goods and services for sale, I must honor that offer. So a pizza restaurant can’t double its prices for Jews, or African-Americans, or refuse service to Muslims. If I refuse to do business on the advertised terms (“We don’t serve your kind!”) I have committed fraud. In these situations, no law protecting LGBT customers would be necessary, because it is already illegal to refuse service.