The law varies from state to state as regards mandatory versus voluntary knowledge of food safety.
In 6 states – California, Texas, Illinois, Arizona, West Virginia, New Mexico, (and some local jurisdictions) – they require ALL food handlers within their limits to have a food handler training certificate from an ANAB-accredited certificate program, demonstrating compliance with ASTM E2659, Standard Practice for Certificate Programs, an American National Standard.
Since the government introduced the Food Safety Modernization Act in 2011, it has become very clear that any business that cannot prove their staff has had basic Food Handler training (either via a course or training from a certified Food Manager), is highly vulnerable to penalties should there be any foodborne illness problems arising.